Just what exactly is a "flat-tappet cam" re:zinc
- Thread starter Nayov
- Start date
- Status
Originally Posted By: Hoosier_Daddy
one thing to consider:
on my volvo 850 it has those flat lifters but they are free to rotate in the well and equalize the wear. some domestic setups i've seen lock the lifters into place which would force them to wear in one way.
The only ones I've ever seen that lock the lifter so that it doesn't rotate are the roller setups. It's essential that the lifters rotate in a flat tappet setup. This was found to be behind many of the GN cam failures. It was the same lobe most of the time, the #3 exhaust I believe. It turned out to be a problem with the block casting with the lifter centered over the cam so that it did not rotate, causing the failure.
one thing to consider:
on my volvo 850 it has those flat lifters but they are free to rotate in the well and equalize the wear. some domestic setups i've seen lock the lifters into place which would force them to wear in one way.
The only ones I've ever seen that lock the lifter so that it doesn't rotate are the roller setups. It's essential that the lifters rotate in a flat tappet setup. This was found to be behind many of the GN cam failures. It was the same lobe most of the time, the #3 exhaust I believe. It turned out to be a problem with the block casting with the lifter centered over the cam so that it did not rotate, causing the failure.
OVERKILL
$100 Site Donor 2021
Originally Posted By: BuickGN
Originally Posted By: widman
Here is how flat tappets wear if there is not enough protection
Is that really the wear surface acting on the cam? Maybe it's the picture but it looks like a rocker on the valve stem end.
Was thinking the same thing, looks like a rocker.
Originally Posted By: widman
Here is how flat tappets wear if there is not enough protection
Is that really the wear surface acting on the cam? Maybe it's the picture but it looks like a rocker on the valve stem end.
Was thinking the same thing, looks like a rocker.
Originally Posted By: ekpolk
Click here to see a nice article that pretty well sets out the basic difference between flat and roller designs.
The pictures are useful, the text has several technical errors.
It's a reasonable layman's explanation of the differences between flat tappet and roller cams if you aren't too fussy about factual details.
Click here to see a nice article that pretty well sets out the basic difference between flat and roller designs.
The pictures are useful, the text has several technical errors.
It's a reasonable layman's explanation of the differences between flat tappet and roller cams if you aren't too fussy about factual details.
Originally Posted By: Pablo
No. And if you think about it, even the API (and ILSAC) in their infinite wisdom would not release an oil specification that would destroy such mundane engines.
Or would they?
And yes, They could care less about the older vehicles. If they create an oil that is better for newer cars but worse for older cars (which they have)they would. Simply because, theoretically, older engines would fail which leads to the owners buying newer cars or there would never be circulation within the market. Manufactures and all who are involved do not want anything to last forever or too long. Then no one would be making money.
Originally Posted By: Pablo
Just because an engine has some form of flat tappet, it is not prone to wear more with SM oils.
Yes it is.
No. And if you think about it, even the API (and ILSAC) in their infinite wisdom would not release an oil specification that would destroy such mundane engines.
Or would they?
And yes, They could care less about the older vehicles. If they create an oil that is better for newer cars but worse for older cars (which they have)they would. Simply because, theoretically, older engines would fail which leads to the owners buying newer cars or there would never be circulation within the market. Manufactures and all who are involved do not want anything to last forever or too long. Then no one would be making money.
Originally Posted By: Pablo
Just because an engine has some form of flat tappet, it is not prone to wear more with SM oils.
Yes it is.
Last edited by a moderator:
Different manufactures use different terminology for some parts. In the world of John Deere a cam follower is the proper term for the part that rides along the camshaft and imparts an upwards pressure on the pushrod that then pushes on one side of the rocker arm that pivots applying downward pressure on the valve stem to force open either an intake or exhaust valve.
It is the followers that are the issue, not the rockers or “tappets” as shown in Widman’s picture. Rockers are usually cheap and far easier to replace than followers. In the case of the 4.0L Jeep engine the rockers can be replaced in less than an hour for less than $100.00 parts.
I find it most peculiar that that in the case of the 4.0 L Jeep engine an engine known for extreme durability and legendary longevity, that within a few months of the adoption and regular use of SM rated engine oil these engines started having camshaft/follower issues. This was happening mostly with engines used hard, as in heavy off roading and rock climbing, not every day street use. The problem was popping up not just with new engines, but also with engines as old as 2002 sometimes older.
Mysteriously engines that had run just fine started having issues, what was the single factor in all cases? The switch from SL to SM oil, it started happening about two oil changes into the use of SM oil. But no it just couldn’t possibly be the oil could it? The API would never push oil that was “better” for the majority of vehicles with little regard for the few older designed solid follower engines still out there.
You would need to be completely blind to look at the 4.0 L camshaft/follower failure timeline and ignore the single thing that changed, the oil. There was a Rubicon in the shop where I worked that first got new camshaft/followers, and within 6,000 miles it needed the same parts replaced. The second go around the owner rightfully so made a big fuss and got a new long block engine from Chrysler, the third time it was in it got a new short block and Delo 400 15W-40 that was the end of the issue. From that point on whenever a camshaft issue was repaired where I worked it got HDEO, and the problem stopped there. Sure, it’s easy for the oil pushers to blame it on the metallurgy, but let’s keep in mind that these engines never showed camshaft/follower issues before the use of SM rated oils.
I believe that there is a significant issue with SM rated engine oil and SOME non roller follower engines. Crane’s Cams has gone out of business, but before they did I had a long conversation about this issue with a rep there, they said the same thing, and Crane’s probably knew more about camshaft than the cumulative knowledge of the members of this forum.
I haven’t checked lately, but John Deere engine oils for heavy duty use, mainly the Plus 50 variety were not API licensed. If you look at the zinc levels in Plus 50, I don’t think it would meet any relatively current classification. The John Deere lubricants course stresses that the world a farm tractor lives in is completely different than most any other engine. When in the field doing tillage work, a farm tractor engine is putting out at or close to 100% power all the time, this is different from a truck that may work to go up the hill then more or less coasts back on down the other side. The only time the farm tractor engine idles down is possibly to turn around at the end of the field; this is at most a matter of seconds. Personally I never idle down the engine to turn around. In construction use, the majority of engines are not run at or near 100% output nearly 100% of the time for hours on end. When a dozer is backing up, or a scraper is running empty, it is relieved of the majority of its load.
The point of this is that John Deere still has a large number of non roller follower engines in use today, in tractors that still get used hard in the fields, and the lowering of zinc in the eyes of John Deere is not a good thing. But hey what do they know about building engines?
Metallurgy my bumm, it’s the oil.
It is the followers that are the issue, not the rockers or “tappets” as shown in Widman’s picture. Rockers are usually cheap and far easier to replace than followers. In the case of the 4.0L Jeep engine the rockers can be replaced in less than an hour for less than $100.00 parts.
I find it most peculiar that that in the case of the 4.0 L Jeep engine an engine known for extreme durability and legendary longevity, that within a few months of the adoption and regular use of SM rated engine oil these engines started having camshaft/follower issues. This was happening mostly with engines used hard, as in heavy off roading and rock climbing, not every day street use. The problem was popping up not just with new engines, but also with engines as old as 2002 sometimes older.
Mysteriously engines that had run just fine started having issues, what was the single factor in all cases? The switch from SL to SM oil, it started happening about two oil changes into the use of SM oil. But no it just couldn’t possibly be the oil could it? The API would never push oil that was “better” for the majority of vehicles with little regard for the few older designed solid follower engines still out there.
You would need to be completely blind to look at the 4.0 L camshaft/follower failure timeline and ignore the single thing that changed, the oil. There was a Rubicon in the shop where I worked that first got new camshaft/followers, and within 6,000 miles it needed the same parts replaced. The second go around the owner rightfully so made a big fuss and got a new long block engine from Chrysler, the third time it was in it got a new short block and Delo 400 15W-40 that was the end of the issue. From that point on whenever a camshaft issue was repaired where I worked it got HDEO, and the problem stopped there. Sure, it’s easy for the oil pushers to blame it on the metallurgy, but let’s keep in mind that these engines never showed camshaft/follower issues before the use of SM rated oils.
I believe that there is a significant issue with SM rated engine oil and SOME non roller follower engines. Crane’s Cams has gone out of business, but before they did I had a long conversation about this issue with a rep there, they said the same thing, and Crane’s probably knew more about camshaft than the cumulative knowledge of the members of this forum.
I haven’t checked lately, but John Deere engine oils for heavy duty use, mainly the Plus 50 variety were not API licensed. If you look at the zinc levels in Plus 50, I don’t think it would meet any relatively current classification. The John Deere lubricants course stresses that the world a farm tractor lives in is completely different than most any other engine. When in the field doing tillage work, a farm tractor engine is putting out at or close to 100% power all the time, this is different from a truck that may work to go up the hill then more or less coasts back on down the other side. The only time the farm tractor engine idles down is possibly to turn around at the end of the field; this is at most a matter of seconds. Personally I never idle down the engine to turn around. In construction use, the majority of engines are not run at or near 100% output nearly 100% of the time for hours on end. When a dozer is backing up, or a scraper is running empty, it is relieved of the majority of its load.
The point of this is that John Deere still has a large number of non roller follower engines in use today, in tractors that still get used hard in the fields, and the lowering of zinc in the eyes of John Deere is not a good thing. But hey what do they know about building engines?
Metallurgy my bumm, it’s the oil.
Originally Posted By: peterdes
Originally Posted By: Pablo
No. And if you think about it, even the API (and ILSAC) in their infinite wisdom would not release an oil specification that would destroy such mundane engines.
Or would they?
And yes, They could care less about the older vehicles. If they create an oil that is better for newer cars but worse for older cars (which they have)they would. Simply because, theoretically, older engines would fail which leads to the owners buying newer cars or there would never be circulation within the market. Manufactures and all who are involved do not want anything to last forever or too long. Then no one would be making money.
Originally Posted By: Pablo
Just because an engine has some form of flat tappet, it is not prone to wear more with SM oils.
Yes it is.
You miss the point. It takes something more than just "flat tappets". I think if you try really hard you can come up with the main reason.
Originally Posted By: Pablo
No. And if you think about it, even the API (and ILSAC) in their infinite wisdom would not release an oil specification that would destroy such mundane engines.
Or would they?
And yes, They could care less about the older vehicles. If they create an oil that is better for newer cars but worse for older cars (which they have)they would. Simply because, theoretically, older engines would fail which leads to the owners buying newer cars or there would never be circulation within the market. Manufactures and all who are involved do not want anything to last forever or too long. Then no one would be making money.
Originally Posted By: Pablo
Just because an engine has some form of flat tappet, it is not prone to wear more with SM oils.
Yes it is.
You miss the point. It takes something more than just "flat tappets". I think if you try really hard you can come up with the main reason.
Originally Posted By: moribundman
Originally Posted By: Pablo
No worries with that bucket set-up.
Hydraulic lifters with "buckets" are obviously common in many engines. All my VW and and Audi engines had that setup. Just to make sure about the used terminology: hydraulic lifters still do qualify as flat tappets, with the "bucket" representing the flat tappet, correct?
As far as I know, running in a flat tappet cam, usually a rebuild, with a low SAPS oil may be less than ideal.
Hydraulic lifters are flat, but in the sphere of valve train worries it's not what people think of/are talking about when they say flat tappet.
I agree fully with your last sentence.
Originally Posted By: Pablo
No worries with that bucket set-up.
Hydraulic lifters with "buckets" are obviously common in many engines. All my VW and and Audi engines had that setup. Just to make sure about the used terminology: hydraulic lifters still do qualify as flat tappets, with the "bucket" representing the flat tappet, correct?
As far as I know, running in a flat tappet cam, usually a rebuild, with a low SAPS oil may be less than ideal.
Hydraulic lifters are flat, but in the sphere of valve train worries it's not what people think of/are talking about when they say flat tappet.
I agree fully with your last sentence.
Originally Posted By: CJWink
You would need to be completely blind to look at the 4.0 L camshaft/follower failure timeline and ignore the single thing that changed, the oil. There was a Rubicon in the shop where I worked that first got new camshaft/followers, and within 6,000 miles it needed the same parts replaced. The second go around the owner rightfully so made a big fuss and got a new long block engine from Chrysler, the third time it was in it got a new short block and Delo 400 15W-40 that was the end of the issue. From that point on whenever a camshaft issue was repaired where I worked it got HDEO, and the problem stopped there. Sure, it’s easy for the oil pushers to blame it on the metallurgy, but let’s keep in mind that these engines never showed camshaft/follower issues before the use of SM rated oils.
Metallurgy my bumm, it’s the oil.
Failure within 6000mi just due to switching to SM? I'm sorry, but that is metallurgy, and Chrysler needs to get its head out of its collective butt. No wonder they're in trouble (repeatedly). What is this junk doing rolling off the assembly line in the 21st century?
It would be one thing to see increased wear over hundreds or thousands of hours or at least in something like the tractor application you describe. Failure within one OCI using a quality SM oil is inexcusable in terms of THE DESIGN. I think when folks are blaming metallurgy they aren't necessarily stating it's a bad batch of parts. It looks like the Jeep's specification is bad.
Perhaps the oil contributes, but perhaps a 21st century car should not have such a poor design incorporated, or perhaps consumers should not be forking over their hard earned cash for this kind of thing and speak with their wallets.
There's an ongoing fascination with obsolete, North American engineering. Whether it's the same as you used to work on during "the war", or it's like your first car in the 50s, people hold on to this "easier to work on" or "easier to modify" sentiment. The only cars I personally count as owning (first-car beaters excluded) were all DOHC, and two of the three had variable valve timing, and I can't say I've ever had a problem working on them. They didn't wear out in one OCI either. They probably also got better fuel economy, higher output efficiency and lower pollution figures than this pushrod stuff too.
It's one thing to have a hobby car which has been restored and needs some special consideration. It's another to keep buying/building the same designs in 2009. Chrysler/Jeep should get a big kick in the can for this fiasco, not those that set the standards for SM formulation.
You would need to be completely blind to look at the 4.0 L camshaft/follower failure timeline and ignore the single thing that changed, the oil. There was a Rubicon in the shop where I worked that first got new camshaft/followers, and within 6,000 miles it needed the same parts replaced. The second go around the owner rightfully so made a big fuss and got a new long block engine from Chrysler, the third time it was in it got a new short block and Delo 400 15W-40 that was the end of the issue. From that point on whenever a camshaft issue was repaired where I worked it got HDEO, and the problem stopped there. Sure, it’s easy for the oil pushers to blame it on the metallurgy, but let’s keep in mind that these engines never showed camshaft/follower issues before the use of SM rated oils.
Metallurgy my bumm, it’s the oil.
Failure within 6000mi just due to switching to SM? I'm sorry, but that is metallurgy, and Chrysler needs to get its head out of its collective butt. No wonder they're in trouble (repeatedly). What is this junk doing rolling off the assembly line in the 21st century?
It would be one thing to see increased wear over hundreds or thousands of hours or at least in something like the tractor application you describe. Failure within one OCI using a quality SM oil is inexcusable in terms of THE DESIGN. I think when folks are blaming metallurgy they aren't necessarily stating it's a bad batch of parts. It looks like the Jeep's specification is bad.
Perhaps the oil contributes, but perhaps a 21st century car should not have such a poor design incorporated, or perhaps consumers should not be forking over their hard earned cash for this kind of thing and speak with their wallets.
There's an ongoing fascination with obsolete, North American engineering. Whether it's the same as you used to work on during "the war", or it's like your first car in the 50s, people hold on to this "easier to work on" or "easier to modify" sentiment. The only cars I personally count as owning (first-car beaters excluded) were all DOHC, and two of the three had variable valve timing, and I can't say I've ever had a problem working on them. They didn't wear out in one OCI either. They probably also got better fuel economy, higher output efficiency and lower pollution figures than this pushrod stuff too.
It's one thing to have a hobby car which has been restored and needs some special consideration. It's another to keep buying/building the same designs in 2009. Chrysler/Jeep should get a big kick in the can for this fiasco, not those that set the standards for SM formulation.
Last edited:
Originally Posted By: Craig in Canada
Originally Posted By: CJWink
You would need to be completely blind to look at the 4.0 L camshaft/follower failure timeline and ignore the single thing that changed, the oil. There was a Rubicon in the shop where I worked that first got new camshaft/followers, and within 6,000 miles it needed the same parts replaced. The second go around the owner rightfully so made a big fuss and got a new long block engine from Chrysler, the third time it was in it got a new short block and Delo 400 15W-40 that was the end of the issue. From that point on whenever a camshaft issue was repaired where I worked it got HDEO, and the problem stopped there. Sure, it’s easy for the oil pushers to blame it on the metallurgy, but let’s keep in mind that these engines never showed camshaft/follower issues before the use of SM rated oils.
Metallurgy my bumm, it’s the oil.
Failure within 6000mi just due to switching to SM? I'm sorry, but that is metallurgy, and Chrysler needs to get its head out of its collective butt. No wonder they're in trouble (repeatedly). What is this junk doing rolling off the assembly line in the 21st century?
It would be one thing to see increased wear over hundreds or thousands of hours or at least in something like the tractor application you describe. Failure within one OCI using a quality SM oil is inexcusable in terms of THE DESIGN. I think when folks are blaming metallurgy they aren't necessarily stating it's a bad batch of parts. It looks like the Jeep's specification is bad.
Perhaps the oil contributes, but perhaps a 21st century car should not have such a poor design incorporated, or perhaps consumers should not be forking over their hard earned cash for this kind of thing and speak with their wallets.
There's an ongoing fascination with obsolete, North American engineering. Whether it's the same as you used to work on during "the war", or it's like your first car in the 50s, people hold on to this "easier to work on" or "easier to modify" sentiment. The only cars I personally count as owning (first-car beaters excluded) were all DOHC, and two of the three had variable valve timing, and I can't say I've ever had a problem working on them. They didn't wear out in one OCI either. They probably also got better fuel economy, higher output efficiency and lower pollution figures than this pushrod stuff too.
It's one thing to have a hobby car which has been restored and needs some special consideration. It's another to keep buying/building the same designs in 2009. Chrysler/Jeep should get a big kick in the can for this fiasco, not those that set the standards for SM formulation.
You're ignoring the fact that many engines were fine until the SM oils came out. Are you really saying it's coincidence that many engines with plenty miles on them mysteriously failed after running an SM oil due to metallurgy issues?
In the turbo Buick world, we saw the same thing happen. Not all failed, in fact many more survived than failed but you can't overlook it when perfectly healthy engines started failing when the only variable you changed was the oil.
I'm not sure why you hate older American cars but the easier and cheaper to modify is very true. It took me $200 to go from high 13s to high 12s. Under $1,500 to run deep in the 11s. And this is with a 6 banger. You still have the Fox bodies and LSx guys that would walk all over imports in a dollar per hp race. Let's not mention the old Mopars, Fords, and Chevy big blocks from the 60s in slightly modded form.
Originally Posted By: CJWink
You would need to be completely blind to look at the 4.0 L camshaft/follower failure timeline and ignore the single thing that changed, the oil. There was a Rubicon in the shop where I worked that first got new camshaft/followers, and within 6,000 miles it needed the same parts replaced. The second go around the owner rightfully so made a big fuss and got a new long block engine from Chrysler, the third time it was in it got a new short block and Delo 400 15W-40 that was the end of the issue. From that point on whenever a camshaft issue was repaired where I worked it got HDEO, and the problem stopped there. Sure, it’s easy for the oil pushers to blame it on the metallurgy, but let’s keep in mind that these engines never showed camshaft/follower issues before the use of SM rated oils.
Metallurgy my bumm, it’s the oil.
Failure within 6000mi just due to switching to SM? I'm sorry, but that is metallurgy, and Chrysler needs to get its head out of its collective butt. No wonder they're in trouble (repeatedly). What is this junk doing rolling off the assembly line in the 21st century?
It would be one thing to see increased wear over hundreds or thousands of hours or at least in something like the tractor application you describe. Failure within one OCI using a quality SM oil is inexcusable in terms of THE DESIGN. I think when folks are blaming metallurgy they aren't necessarily stating it's a bad batch of parts. It looks like the Jeep's specification is bad.
Perhaps the oil contributes, but perhaps a 21st century car should not have such a poor design incorporated, or perhaps consumers should not be forking over their hard earned cash for this kind of thing and speak with their wallets.
There's an ongoing fascination with obsolete, North American engineering. Whether it's the same as you used to work on during "the war", or it's like your first car in the 50s, people hold on to this "easier to work on" or "easier to modify" sentiment. The only cars I personally count as owning (first-car beaters excluded) were all DOHC, and two of the three had variable valve timing, and I can't say I've ever had a problem working on them. They didn't wear out in one OCI either. They probably also got better fuel economy, higher output efficiency and lower pollution figures than this pushrod stuff too.
It's one thing to have a hobby car which has been restored and needs some special consideration. It's another to keep buying/building the same designs in 2009. Chrysler/Jeep should get a big kick in the can for this fiasco, not those that set the standards for SM formulation.
You're ignoring the fact that many engines were fine until the SM oils came out. Are you really saying it's coincidence that many engines with plenty miles on them mysteriously failed after running an SM oil due to metallurgy issues?
In the turbo Buick world, we saw the same thing happen. Not all failed, in fact many more survived than failed but you can't overlook it when perfectly healthy engines started failing when the only variable you changed was the oil.
I'm not sure why you hate older American cars but the easier and cheaper to modify is very true. It took me $200 to go from high 13s to high 12s. Under $1,500 to run deep in the 11s. And this is with a 6 banger. You still have the Fox bodies and LSx guys that would walk all over imports in a dollar per hp race. Let's not mention the old Mopars, Fords, and Chevy big blocks from the 60s in slightly modded form.
Originally Posted By: aquariuscsm
Originally Posted By: ekpolk
Click here to see a nice article that pretty well sets out the basic difference between flat and roller designs.
Excellent article! That`d how I always thought a flat tappet cam looked. Seems way more primitive than a roller cam. Are all modern engines roller cam nowadays? Seems like a much better design wear-wise.
There is actually almost no wear on a flat tappet cam, PROVIDED that a) the cam is properly surface-hardened after being formed at the foundry and cam grinder, b) the lifters are likewise properly surface hardened, c) the cam and lifter set was properly broken in (EXTREMELY critical step), and d) there is adequate oil flow. Once the cam and lifter surface have "worn in" against each other, the cam can run half a million miles without removing but a few tens of microns of material! In fact, if more material *does* wear away, the cam will quickly fail because the surface hardening layer is quite thin.
ZDDP additives are most critical during break-in, and can be drastically reduced afterward. I don't think we really know what the lower threshhold is for different engine combinations yet. I would bet that virtually all flat-tappet overhead cam engines (like the Nissan and BMW mentioned in this thread) will be fine with SM oils. Same for low-RPM pushrod engines like Jeep 4.0 and Range Rover v8s. It gets questionable with older American v8s that are more performance oriented. Upgrades like modern "beehive" valvesprings that maintain valve control with much less seat and lifter toe pressures than old-style dual valve springs with dampers will certainly extend cam life and reduce the need for ZDDP. But the problem is that a little wear on a cam will quickly cascade to a total failure if the wear breaches the surface-hardening of the cam. So finding the limit is going to cost a few cams, and I don't want one of them to be mine. There's also the problem of knowing whether it was a bad cam, bad lifter, or oil that caused the problem. My personal experience is that cams coming out of the grinders today, while much more advanced in terms of the science behind the lift, duration, overlap, etc. and capable of much greater performance than old cams, are C-R-A-P in terms of the quality of the blank casting from which they are ground, and sometimes even the finishing steps after grinding. I don't know if its junk from offshore, tooling getting old, or just plain old cutting corners for profit, but holding a new cam by a vintage one often shows *visible* differences in the surface quality and absence of voids and irregularities in the older casting.
Rollers are much better and have taken over the market, but they do have their own problems, too. The lifters have to be very precisely aligned, any sideways "crab angle" of the roller will fail the cam. Rollers on the lifters sometimes seize or break, and when that happens its UUUUUUG-LEEE! Lifter bores can get torn right out of blocks or heads. At least when a flat tappet cam fails, the lobe usually just wears away, the lifter goes cup-shaped, and the valve quits opening, and the filter traps all the fine particles that wear off- nothing sudden or violently destructive like happens with rollers.
Originally Posted By: ekpolk
Click here to see a nice article that pretty well sets out the basic difference between flat and roller designs.
Excellent article! That`d how I always thought a flat tappet cam looked. Seems way more primitive than a roller cam. Are all modern engines roller cam nowadays? Seems like a much better design wear-wise.
There is actually almost no wear on a flat tappet cam, PROVIDED that a) the cam is properly surface-hardened after being formed at the foundry and cam grinder, b) the lifters are likewise properly surface hardened, c) the cam and lifter set was properly broken in (EXTREMELY critical step), and d) there is adequate oil flow. Once the cam and lifter surface have "worn in" against each other, the cam can run half a million miles without removing but a few tens of microns of material! In fact, if more material *does* wear away, the cam will quickly fail because the surface hardening layer is quite thin.
ZDDP additives are most critical during break-in, and can be drastically reduced afterward. I don't think we really know what the lower threshhold is for different engine combinations yet. I would bet that virtually all flat-tappet overhead cam engines (like the Nissan and BMW mentioned in this thread) will be fine with SM oils. Same for low-RPM pushrod engines like Jeep 4.0 and Range Rover v8s. It gets questionable with older American v8s that are more performance oriented. Upgrades like modern "beehive" valvesprings that maintain valve control with much less seat and lifter toe pressures than old-style dual valve springs with dampers will certainly extend cam life and reduce the need for ZDDP. But the problem is that a little wear on a cam will quickly cascade to a total failure if the wear breaches the surface-hardening of the cam. So finding the limit is going to cost a few cams, and I don't want one of them to be mine. There's also the problem of knowing whether it was a bad cam, bad lifter, or oil that caused the problem. My personal experience is that cams coming out of the grinders today, while much more advanced in terms of the science behind the lift, duration, overlap, etc. and capable of much greater performance than old cams, are C-R-A-P in terms of the quality of the blank casting from which they are ground, and sometimes even the finishing steps after grinding. I don't know if its junk from offshore, tooling getting old, or just plain old cutting corners for profit, but holding a new cam by a vintage one often shows *visible* differences in the surface quality and absence of voids and irregularities in the older casting.
Rollers are much better and have taken over the market, but they do have their own problems, too. The lifters have to be very precisely aligned, any sideways "crab angle" of the roller will fail the cam. Rollers on the lifters sometimes seize or break, and when that happens its UUUUUUG-LEEE! Lifter bores can get torn right out of blocks or heads. At least when a flat tappet cam fails, the lobe usually just wears away, the lifter goes cup-shaped, and the valve quits opening, and the filter traps all the fine particles that wear off- nothing sudden or violently destructive like happens with rollers.
Originally Posted By: Hoosier_Daddy
one thing to consider:
on my volvo 850 it has those flat lifters but they are free to rotate in the well and equalize the wear. some domestic setups i've seen lock the lifters into place which would force them to wear in one way.
That's flat (pun intended) not true. EVERY flat-tappet pushrod domestic I've ever worked on built from the 40s to the 80s when most of them went roller (Ford, GM, Chrysler, AMC) has had lifters that are not only free to spin in their bores, but the cam lobes are ground in such a way to INDUCE spin. AFAIK, there is NO flat-tappet design that doesn't allow the lifter to spin for the very reason you state.
Roller lifters, OTOH, have to be locked in precise alignment with the cam's direction of rotation so there is no sliding between the roller and the lobe.
one thing to consider:
on my volvo 850 it has those flat lifters but they are free to rotate in the well and equalize the wear. some domestic setups i've seen lock the lifters into place which would force them to wear in one way.
That's flat (pun intended) not true. EVERY flat-tappet pushrod domestic I've ever worked on built from the 40s to the 80s when most of them went roller (Ford, GM, Chrysler, AMC) has had lifters that are not only free to spin in their bores, but the cam lobes are ground in such a way to INDUCE spin. AFAIK, there is NO flat-tappet design that doesn't allow the lifter to spin for the very reason you state.
Roller lifters, OTOH, have to be locked in precise alignment with the cam's direction of rotation so there is no sliding between the roller and the lobe.
Originally Posted By: Craig in Canada
Originally Posted By: CJWink
You would need to be completely blind to look at the 4.0 L camshaft/follower failure timeline and ignore the single thing that changed, the oil. There was a Rubicon in the shop where I worked that first got new camshaft/followers, and within 6,000 miles it needed the same parts replaced. The second go around the owner rightfully so made a big fuss and got a new long block engine from Chrysler, the third time it was in it got a new short block and Delo 400 15W-40 that was the end of the issue. From that point on whenever a camshaft issue was repaired where I worked it got HDEO, and the problem stopped there. Sure, it’s easy for the oil pushers to blame it on the metallurgy, but let’s keep in mind that these engines never showed camshaft/follower issues before the use of SM rated oils.
Metallurgy my bumm, it’s the oil.
Failure within 6000mi just due to switching to SM? I'm sorry, but that is metallurgy, and Chrysler needs to get its head out of its collective butt.
Its not Chrysler, and its not metallurgy, and its not JUST the oil in most cases. There are TWO conditions here: 1) the switch to lower-phosphorous oil, and 2) the engines that are failing are used in hard offroading. HELLO!! Hard offroading tends to put more silicates in the oil from dust and dirt. Offroading requires more time at high torque/low RPM where metal-to-metal contact is most likely. Most importantly, offroading frequently starves various parts for oil because of the angles involved, and that's EXACTLY when ZDDP is the barrier of last resort against wear. So long as the engine is in the hydrodynamic regime (all surfaces fully separated by an oil film) ZDDP doesn't come into play, but when things go "dry," ZDDP is critical.
Chrysler put over 6 million 4.0 engines into Jeep Cherokees ALONE, not counting Wranglers and Grand Cherokees. They are NOT failing left and right in street use, and they are NOT a flawed design in any way. But the fact that failures do happen in offroading does point out one reason why an oil that passes the Sequence IV-a test is still inadequate for some applications.
As has been pointed out in other threads, its not actually the SM rating that limits oil to <800 PPM phosphorous, its one of the other more obscure ratings (ILSAC? ACEA? I forget the alphabet soup). SM-rated HDEOs like Rotella T, Delo, Delvac, etc. still have plenty of zinc and phosphorous. Serious offroaders tend to know that fact and stick to those oils.
Originally Posted By: CJWink
You would need to be completely blind to look at the 4.0 L camshaft/follower failure timeline and ignore the single thing that changed, the oil. There was a Rubicon in the shop where I worked that first got new camshaft/followers, and within 6,000 miles it needed the same parts replaced. The second go around the owner rightfully so made a big fuss and got a new long block engine from Chrysler, the third time it was in it got a new short block and Delo 400 15W-40 that was the end of the issue. From that point on whenever a camshaft issue was repaired where I worked it got HDEO, and the problem stopped there. Sure, it’s easy for the oil pushers to blame it on the metallurgy, but let’s keep in mind that these engines never showed camshaft/follower issues before the use of SM rated oils.
Metallurgy my bumm, it’s the oil.
Failure within 6000mi just due to switching to SM? I'm sorry, but that is metallurgy, and Chrysler needs to get its head out of its collective butt.
Its not Chrysler, and its not metallurgy, and its not JUST the oil in most cases. There are TWO conditions here: 1) the switch to lower-phosphorous oil, and 2) the engines that are failing are used in hard offroading. HELLO!! Hard offroading tends to put more silicates in the oil from dust and dirt. Offroading requires more time at high torque/low RPM where metal-to-metal contact is most likely. Most importantly, offroading frequently starves various parts for oil because of the angles involved, and that's EXACTLY when ZDDP is the barrier of last resort against wear. So long as the engine is in the hydrodynamic regime (all surfaces fully separated by an oil film) ZDDP doesn't come into play, but when things go "dry," ZDDP is critical.
Chrysler put over 6 million 4.0 engines into Jeep Cherokees ALONE, not counting Wranglers and Grand Cherokees. They are NOT failing left and right in street use, and they are NOT a flawed design in any way. But the fact that failures do happen in offroading does point out one reason why an oil that passes the Sequence IV-a test is still inadequate for some applications.
As has been pointed out in other threads, its not actually the SM rating that limits oil to <800 PPM phosphorous, its one of the other more obscure ratings (ILSAC? ACEA? I forget the alphabet soup). SM-rated HDEOs like Rotella T, Delo, Delvac, etc. still have plenty of zinc and phosphorous. Serious offroaders tend to know that fact and stick to those oils.
Originally Posted By: 440Magnum
the engines that are failing are used in hard offroading. HELLO!!
Serious offroaders tend to know that fact and stick to those oils.
Not exactly true. The "offroading" population in the jeep world is so small compared to how many units they actually sell. Yes, the condition off road will be harder on your engine but I doubt that is causing engine failure. Heavy towing puts much more strain on an engine than offroading. Its the oil. Plain and simple.
Yep. I actually own a discovery with the rover V8. Its built to offroad and most if not everyone on the rover forums knows they should stick to those kind of oils; HDEO's, higher zddp PCMOs. ect.
the engines that are failing are used in hard offroading. HELLO!!
Serious offroaders tend to know that fact and stick to those oils.
Not exactly true. The "offroading" population in the jeep world is so small compared to how many units they actually sell. Yes, the condition off road will be harder on your engine but I doubt that is causing engine failure. Heavy towing puts much more strain on an engine than offroading. Its the oil. Plain and simple.
Yep. I actually own a discovery with the rover V8. Its built to offroad and most if not everyone on the rover forums knows they should stick to those kind of oils; HDEO's, higher zddp PCMOs. ect.
Last edited by a moderator:
Originally Posted By: 440Magnum
I would bet that virtually all flat-tappet overhead cam engines (like the Nissan and BMW mentioned in this thread) will be fine with SM oils. Same for low-RPM pushrod engines like Jeep 4.0 and Range Rover v8s.
From first hand experience in the rover world the SM oils are just not good enough for the rover V8. It is almost gospel in the rover world that you should run a oil with high zddp and high HTHS. The rover v8s are practically bullet proof that you can be put through [censored] and back all over the world using the lowest grade fluids when you're in the middle of nowhere in south america. That's what the rover v8 is made for. However, you're going to get a much longer life out of the engine if you use an oil with higher zddp/HTHS.
I would bet that virtually all flat-tappet overhead cam engines (like the Nissan and BMW mentioned in this thread) will be fine with SM oils. Same for low-RPM pushrod engines like Jeep 4.0 and Range Rover v8s.
From first hand experience in the rover world the SM oils are just not good enough for the rover V8. It is almost gospel in the rover world that you should run a oil with high zddp and high HTHS. The rover v8s are practically bullet proof that you can be put through [censored] and back all over the world using the lowest grade fluids when you're in the middle of nowhere in south america. That's what the rover v8 is made for. However, you're going to get a much longer life out of the engine if you use an oil with higher zddp/HTHS.
Most cams are flat tappet type - OHC or DOHC are flat tappets. Some of course have rollers that ride on the cam instead of the sliding wiping type.
After break in, there should be no problems with today's engines
and most of the older ones, except for high performance ones or after market cammed ones.
After break in, there should be no problems with today's engines
and most of the older ones, except for high performance ones or after market cammed ones.
Originally Posted By: BuickGN
You're ignoring the fact that many engines were fine until the SM oils came out. Are you really saying it's coincidence that many engines with plenty miles on them mysteriously failed after running an SM oil due to metallurgy issues?
In the turbo Buick world, we saw the same thing happen. Not all failed, in fact many more survived than failed but you can't overlook it when perfectly healthy engines started failing when the only variable you changed was the oil.
I'm not sure why you hate older American cars but the easier and cheaper to modify is very true. It took me $200 to go from high 13s to high 12s. Under $1,500 to run deep in the 11s. And this is with a 6 banger. You still have the Fox bodies and LSx guys that would walk all over imports in a dollar per hp race. Let's not mention the old Mopars, Fords, and Chevy big blocks from the 60s in slightly modded form.
I'm not ignoring it, I just don't believe the oil is what needs fixing in the situation I quoted.
For this discussion I don't care about horsepower-per-dollar modification comparisons, neither do the API people, neither do most Joe Average folks who buy a Jeep to drive the kids to school. *If* I had chosen an American family vehicle with such "classic" engineering and it ground itself to engine replacement in
Quoting quarter mile times etc... it's clear that you've got a special-interest vehicle. Feel free to run whatever special interest fluids you want in it and argue that API SM isn't fit for special interest, modified (old) vehicles.
Old, special interest technology that will cause engine failure in a single OCI has no place in a modern grocery-getter.
Don't mix "Mopars from the 60s" and "I can get into the 11s with $1500" with a 2009 mom's taxi.
My beef isn't particularly with fans of old American cars (although I don't share the interest), it's with the continuance of out-dated, sub-par engineering and specifications by the American car companies in new models. I'm not a fan of American cars old or new as a result. Last I checked, they weren't selling Jeeps at bargain basement prices which would account for poor metallurgy specs and no advancements in engine technology. All the while we're trying to reduce pollution and carbon footprint and they're still cranking out engines with pushrods, fixed cam timing, and still charging prices like they're recovering R&D spending...
You're ignoring the fact that many engines were fine until the SM oils came out. Are you really saying it's coincidence that many engines with plenty miles on them mysteriously failed after running an SM oil due to metallurgy issues?
In the turbo Buick world, we saw the same thing happen. Not all failed, in fact many more survived than failed but you can't overlook it when perfectly healthy engines started failing when the only variable you changed was the oil.
I'm not sure why you hate older American cars but the easier and cheaper to modify is very true. It took me $200 to go from high 13s to high 12s. Under $1,500 to run deep in the 11s. And this is with a 6 banger. You still have the Fox bodies and LSx guys that would walk all over imports in a dollar per hp race. Let's not mention the old Mopars, Fords, and Chevy big blocks from the 60s in slightly modded form.
I'm not ignoring it, I just don't believe the oil is what needs fixing in the situation I quoted.
For this discussion I don't care about horsepower-per-dollar modification comparisons, neither do the API people, neither do most Joe Average folks who buy a Jeep to drive the kids to school. *If* I had chosen an American family vehicle with such "classic" engineering and it ground itself to engine replacement in
Quoting quarter mile times etc... it's clear that you've got a special-interest vehicle. Feel free to run whatever special interest fluids you want in it and argue that API SM isn't fit for special interest, modified (old) vehicles.
Old, special interest technology that will cause engine failure in a single OCI has no place in a modern grocery-getter.
Don't mix "Mopars from the 60s" and "I can get into the 11s with $1500" with a 2009 mom's taxi.
My beef isn't particularly with fans of old American cars (although I don't share the interest), it's with the continuance of out-dated, sub-par engineering and specifications by the American car companies in new models. I'm not a fan of American cars old or new as a result. Last I checked, they weren't selling Jeeps at bargain basement prices which would account for poor metallurgy specs and no advancements in engine technology. All the while we're trying to reduce pollution and carbon footprint and they're still cranking out engines with pushrods, fixed cam timing, and still charging prices like they're recovering R&D spending...
- Joined
- Jun 2, 2003
- Messages
- 23,591
The buckets on the hydraulic lifters in my car's engine can, or rather will, rotate. At over 180k miles, the lifters are still fine. The cam lobes show merely some "polishing." I have been using SM oils since their introduction.
PS: The valves rotate freely, also.
PS: The valves rotate freely, also.
Originally Posted By: Craig in Canada
Originally Posted By: BuickGN
You're ignoring the fact that many engines were fine until the SM oils came out. Are you really saying it's coincidence that many engines with plenty miles on them mysteriously failed after running an SM oil due to metallurgy issues?
In the turbo Buick world, we saw the same thing happen. Not all failed, in fact many more survived than failed but you can't overlook it when perfectly healthy engines started failing when the only variable you changed was the oil.
I'm not sure why you hate older American cars but the easier and cheaper to modify is very true. It took me $200 to go from high 13s to high 12s. Under $1,500 to run deep in the 11s. And this is with a 6 banger. You still have the Fox bodies and LSx guys that would walk all over imports in a dollar per hp race. Let's not mention the old Mopars, Fords, and Chevy big blocks from the 60s in slightly modded form.
I'm not ignoring it, I just don't believe the oil is what needs fixing in the situation I quoted.
For this discussion I don't care about horsepower-per-dollar modification comparisons, neither do the API people, neither do most Joe Average folks who buy a Jeep to drive the kids to school. *If* I had chosen an American family vehicle with such "classic" engineering and it ground itself to engine replacement in
Quoting quarter mile times etc... it's clear that you've got a special-interest vehicle. Feel free to run whatever special interest fluids you want in it and argue that API SM isn't fit for special interest, modified (old) vehicles.
Old, special interest technology that will cause engine failure in a single OCI has no place in a modern grocery-getter.
Don't mix "Mopars from the 60s" and "I can get into the 11s with $1500" with a 2009 mom's taxi.
My beef isn't particularly with fans of old American cars (although I don't share the interest), it's with the continuance of out-dated, sub-par engineering and specifications by the American car companies in new models. I'm not a fan of American cars old or new as a result. Last I checked, they weren't selling Jeeps at bargain basement prices which would account for poor metallurgy specs and no advancements in engine technology. All the while we're trying to reduce pollution and carbon footprint and they're still cranking out engines with pushrods, fixed cam timing, and still charging prices like they're recovering R&D spending...
The whole thing went straight over your head.
Flat tappet engines ran great on the oil of the time. You can't blame the engine because someone decided to change the oil chemistry.
Show me where this import [censored] is superior. Let me guess, pushrods are outdated therfore American cars suck. The plain and simple of it is my GN will take a dump on pretty much anything you can buy off the showroom floor with it's outdated 12 valves and pushrods. What can you buy that's faster than a ZR1 for under $200,000? How many imports can make 800hp reliably and up to 1,000hp on the stock bottom end like the Mustang Cobra?
How about fuel economy? Want to put my 3.2L 210whp TL up against an LS1? It's identical with the exception the LSx engines make 100 more hp.
The almost unnoticable push in the back when my TL hits vtec is cute, but the car is very forgettable, 24 valves and all. How do DOHC and SOHC engines get you to the grocery store any better than pushrod engines?
You talk of these engines like there has been no advancement since the 60s. Do you have any idea how many advancement and upgrades were in the then new LSx series engines? My guess is you don't, you just judge it by how many valves it has or whether it has pushrods. Last I checked, Ford has been producing SOHC and DOHC engines for years. I can think of a couple of 60s models from Chevy and Ford that used a SOHC.
There are people like me that prefer the torque and laid back manner of the pushrod Buick 3.8L for grocery getting vs something that has to shift at 3K or greater just to get moving.
Originally Posted By: BuickGN
You're ignoring the fact that many engines were fine until the SM oils came out. Are you really saying it's coincidence that many engines with plenty miles on them mysteriously failed after running an SM oil due to metallurgy issues?
In the turbo Buick world, we saw the same thing happen. Not all failed, in fact many more survived than failed but you can't overlook it when perfectly healthy engines started failing when the only variable you changed was the oil.
I'm not sure why you hate older American cars but the easier and cheaper to modify is very true. It took me $200 to go from high 13s to high 12s. Under $1,500 to run deep in the 11s. And this is with a 6 banger. You still have the Fox bodies and LSx guys that would walk all over imports in a dollar per hp race. Let's not mention the old Mopars, Fords, and Chevy big blocks from the 60s in slightly modded form.
I'm not ignoring it, I just don't believe the oil is what needs fixing in the situation I quoted.
For this discussion I don't care about horsepower-per-dollar modification comparisons, neither do the API people, neither do most Joe Average folks who buy a Jeep to drive the kids to school. *If* I had chosen an American family vehicle with such "classic" engineering and it ground itself to engine replacement in
Quoting quarter mile times etc... it's clear that you've got a special-interest vehicle. Feel free to run whatever special interest fluids you want in it and argue that API SM isn't fit for special interest, modified (old) vehicles.
Old, special interest technology that will cause engine failure in a single OCI has no place in a modern grocery-getter.
Don't mix "Mopars from the 60s" and "I can get into the 11s with $1500" with a 2009 mom's taxi.
My beef isn't particularly with fans of old American cars (although I don't share the interest), it's with the continuance of out-dated, sub-par engineering and specifications by the American car companies in new models. I'm not a fan of American cars old or new as a result. Last I checked, they weren't selling Jeeps at bargain basement prices which would account for poor metallurgy specs and no advancements in engine technology. All the while we're trying to reduce pollution and carbon footprint and they're still cranking out engines with pushrods, fixed cam timing, and still charging prices like they're recovering R&D spending...
The whole thing went straight over your head.
Flat tappet engines ran great on the oil of the time. You can't blame the engine because someone decided to change the oil chemistry.
Show me where this import [censored] is superior. Let me guess, pushrods are outdated therfore American cars suck. The plain and simple of it is my GN will take a dump on pretty much anything you can buy off the showroom floor with it's outdated 12 valves and pushrods. What can you buy that's faster than a ZR1 for under $200,000? How many imports can make 800hp reliably and up to 1,000hp on the stock bottom end like the Mustang Cobra?
How about fuel economy? Want to put my 3.2L 210whp TL up against an LS1? It's identical with the exception the LSx engines make 100 more hp.
The almost unnoticable push in the back when my TL hits vtec is cute, but the car is very forgettable, 24 valves and all. How do DOHC and SOHC engines get you to the grocery store any better than pushrod engines?
You talk of these engines like there has been no advancement since the 60s. Do you have any idea how many advancement and upgrades were in the then new LSx series engines? My guess is you don't, you just judge it by how many valves it has or whether it has pushrods. Last I checked, Ford has been producing SOHC and DOHC engines for years. I can think of a couple of 60s models from Chevy and Ford that used a SOHC.
There are people like me that prefer the torque and laid back manner of the pushrod Buick 3.8L for grocery getting vs something that has to shift at 3K or greater just to get moving.
Originally Posted By: CJWink
The 4.0 Jeep engine is currently and has been having camshaft issues for the past few years, there are a number of reported failures talked about on the Rubicon Owners Forum, and on a few other web sites devoted to Jeeps.
I primarily work with John Deere, but from time to time have worked at Jeep dealerships, most recently 2006- 2007. We had a number of newer production Wranglers ending up with new camshafts. I refuse to use SM rated oil in my 2006 Rubicon except that the new Delo LE is SM rated, and I will use it. I have noticed the Mobil 1 HM is SL rated and I am seriously considering switching to it.
There is a notion that you can use just about any oil in the 4.0 and you will be fine however for the duration of my time at the last Jeep dealership the mechanic who did heavy engine work was consistently replacing a cam every week or two, the Jeeeps ranged in age from about 2002 to 2006.
Well, speaking for my 96 Cherokee's 4.0, it's been using SM oil since it came out and hasn't had any issues.
The 4.0 Jeep engine is currently and has been having camshaft issues for the past few years, there are a number of reported failures talked about on the Rubicon Owners Forum, and on a few other web sites devoted to Jeeps.
I primarily work with John Deere, but from time to time have worked at Jeep dealerships, most recently 2006- 2007. We had a number of newer production Wranglers ending up with new camshafts. I refuse to use SM rated oil in my 2006 Rubicon except that the new Delo LE is SM rated, and I will use it. I have noticed the Mobil 1 HM is SL rated and I am seriously considering switching to it.
There is a notion that you can use just about any oil in the 4.0 and you will be fine however for the duration of my time at the last Jeep dealership the mechanic who did heavy engine work was consistently replacing a cam every week or two, the Jeeeps ranged in age from about 2002 to 2006.
Well, speaking for my 96 Cherokee's 4.0, it's been using SM oil since it came out and hasn't had any issues.
- Status
Similar threads
- Locked
- Locked
