5.7 Hemi cams

[OVERKILL]

How do you know cam metallurgy is very questionable? How do you know it's not something else like a lubrication issue or a lifter issue?

In my career I've had many clients think there was a problem with metallurgy in their product, only to find the metallurgy was okay, and the problem was their design or something else.

I've also been involved with cam design in my career.

Given your experience, what do you think the limitations of a SADI core are in terms of aggressiveness? When I had my custom cam ground for my 302 the grinder only used billet blanks because of the ramps and RPM range anticipated. He felt SADI cores flexed too much and weren't sufficient to handle things.

I ask because the HEMI cams aren't exactly tame. GM is using billet cores and while they are having the same lifter failure issue, the cams don't seem to be having the same problems.

 

[SteveSRT8]

How do you know cam metallurgy is very questionable? How do you know it's not something else like a lubrication issue or a lifter issue?

In my career I've had many clients think there was a problem with metallurgy in their product, only to find the metallurgy was okay, and the problem was their design or something else.

I've also been involved with cam design in my career.

The opinion is shared by the master cam grinder at Howard's cams. They are very old drag racing friends of ours and i believe they are correct. He had both lifters and cam to examine, as he ground us a brand new one!

 

[CarDocDude]

Any reason you didn't look at aftermarket?

Also, maybe send the cam to a cam manufacturer and see what they say it is - or at least the pictures. They would know above all else most likely.

Yes, I needed to maintain the MDS as I love how efficient this engine is when driven normally. Most aftermarket cams eliminated MDS and aftermarket OE grind cams scare me.

 

[CarDocDude]

Assuming you still have the old lifters around, can you take them apart? Would be quite interested to see what the rollers, pins and needles look like, given your somewhat unique situation here.

I’ve since thrown them out. I will say I examined my replacement cam under magnification and the grind was very smooth. Looked like a much better quality piece.

 

[CarDocDude]

Without personally examining the lobes, it looks like spall debris denting... meaning the dents came after the damaged lobe started shedding material. If this denting preceded lobe damage, then there was contamination that possibly interfered with proper needle roller operation in the lifters, causing skidding.

Good point however the “denting” is in areas where the roller made no contact with the lobe (the edges). I still think it was a piss-poor casting or grind in my case.

 

[CarDocDude]

I just want to thank everyone for their input, very informational and lots of good point of views.

 

[neo4]

I ask because the HEMI cams aren't exactly tame. GM is using billet cores and while they are having the same lifter failure issue, the cams don't seem to be having the same problems.

What years/cars is the GM lifter issue you're referring to?

 

[clinebarger]

Given your experience, what do you think the limitations of a SADI core are in terms of aggressiveness? When I had my custom cam ground for my 302 the grinder only used billet blanks because of the ramps and RPM range anticipated. He felt SADI cores flexed too much and weren't sufficient to handle things.

I ask because the HEMI cams aren't exactly tame. GM is using billet cores and while they are having the same lifter failure issue, the cams don't seem to be having the same problems.

They're not exactly same. While I've seen many GM lifters have Spalling of the Lifter Roller even progressing into the roller locking down & skidding across the cam lobe.
With the Mopar SADI Cam Cores....Is it the Chicken or the Egg? There IS an issue with using case hardened Cast cam cores that's was well documented before the Gen III Hemi was put into production. In fact early non-MDS Gen III Hemi's had billet lobed camshafts that rarely failed.

 

[tshephard]

I have two former cop chargers, both had extremely excessive idle hours and new cams/lifters when I got them (one at 90K; other at 100K). Cams and lifters were whatever dealerships are supposed to replace failed 5.7 hardware with, nothing fancy.

Did you do the cam/lifters? Pics?

 

[Jetronic]

Remember, oil pressure doesn't lubricate, it's just the indication of back-pressure in the system. 30psi or 40psi, the pump is positive displacement, so it is moving the same amount of oil.

But also remember some backpressure is created by moving a viscous fluid through the system. So if a minimal backpressure isn't reached you can't guarantee all engine parts get an adequate oil supply. The less viscous the oil, the lower the backpressure can go, but also the more oil you will need to push through.

the low pressure warning should be sufficient, and ofcourse I know you already know this, but maybe some othere readers can use the reminder.

 

[Danno]

What years/cars is the GM lifter issue you're referring to?

Sample of one, but waiting on a trade in on a 2021 Silverado 5.3, lifters problem, warranty repair at 15k miles.
Lifters are back ordered 4 weeks now.

 

[OVERKILL]

What years/cars is the GM lifter issue you're referring to?

Roughly the same range as the HEMI's, so like ~2005 on up IIRC. It corresponds, mostly, with the introduction of MDS and AFM but, at least with FCA, isn't related to the system itself.

 

[OVERKILL]

They're not exactly same. While I've seen many GM lifters have Spalling of the Lifter Roller even progressing into the roller locking down & skidding across the cam lobe.
With the Mopar SADI Cam Cores....Is it the Chicken or the Egg? There IS an issue with using case hardened Cast cam cores that's was well documented before the Gen III Hemi was put into production. In fact early non-MDS Gen III Hemi's had billet lobed camshafts that rarely failed.

That's why I found @SteveSRT8's issue he described above so surprising, as he has a non-MDS SRT-8 6.1L. I guess it is new enough to have the SADI core.

 

[el Nuke]

Did you do the cam/lifters? Pics?

Both cars had their cam & lifters replaced at a local Dodge dealership while still doing PD duty. I only acquired the cars after they were retired from duty and already had the replacement cam and lifters.

 

[bullwinkle]

Correct me if I’m wrong, but isn’t that one picture of the cam showing a chunk that has spalled out? Not sure how lifters could cause that, it looks more likely to be really poor metallurgy or hardening of the cam.

 

[ARB1977]

The reason to stay away from Ram. For as long that engine has been out they can’t get their act together. As a consumer I’d be ******.

 

[ZeeOSix]

But also remember some backpressure is created by moving a viscous fluid through the system. So if a minimal backpressure isn't reached you can't guarantee all engine parts get an adequate oil supply. The less viscous the oil, the lower the backpressure can go, but also the more oil you will need to push through.

Re: your bold sentence. Example: If you see 60 PSI of oil pressure with 5W-30 at 4000 RPM, but see 50 PSI oil pressure with 5W-20 at 4000 RPM, you are still basically getting the same volumetric oil flow through the oiling system due to the PD oil pump. The volumetric flow split among all oiling system circuits should still follow the split ratios as the pressure decreases. Adequate oil volume supply equals adequate lubrication. Only time a lower oil pressure would be of concern is if some components like variable valve timing mechanism or similar needs a minimum oil pressure to operate, and the oil being used is too thin to achieve that minimum oil pressure.

 

[Jetronic]

Re: your bold sentence. Example: If you see 60 PSI of oil pressure with 5W-30 at 4000 RPM, but see 50 PSI oil pressure with 5W-20 at 4000 RPM, you are still basically getting the same volumetric oil flow through the oiling system due to the PD oil pump. The volumetric flow split among all oiling system circuits should still follow the split ratios as the pressure decreases. Adequate oil volume supply equals adequate lubrication. Only time a lower oil pressure would be of concern is if some components like variable valve timing mechanism or similar needs a minimum oil pressure to operate, and the oil being used is too thin to achieve that minimum oil pressure.

There's no issue at the upper limit, rather at the lower limit... pressure could drop too far, doesn't matter if you're pumping the same gpm if you leak it out as fast as you pump it. In any case you need to know what the new normal is.

 

[ZeeOSix]

There's no issue at the upper limit, rather at the lower limit... pressure could drop too far, doesn't matter if you're pumping the same gpm if you leak it out as fast as you pump it. In any case you need to know what the new normal is.

The supply oil pressure seen at the inlet of the oiling system is primarily a result of the flow resistance of all the journal bearings. Look at how journal bearings operate. As long as there is an adequate supply volume at the bearing inlet to take in while it's rotating, then the bearing will flow oil and produce a MOFT based on the oil viscosity - the thinner the oil, the more volume the bearing will flow but the MOFT will also decrease, and the lower the indicated oil pressure will be.

It's possible that the lubrication will be inadequate from the actual viscosity, but not from the oil pressure as long as there is an adequate supply volume so the bearings are not starved of oil. Lubrication of all non-pressure supplied (splashed) areas of the engine like cams lobes, rocker arms, cam chains, piston skirts, piston rings, etc again depend on the oil viscosity to provide an adequate MOFT, and as long as an adequate volume of oil is supplied/splashed on the parts it doesn't really matter what the supply oil pressure is.

Like said above, if there are mechanical mechanisms that are designed to operate with a minimum oil pressure, then obviously there will be a point where the oil pressure will be too low to correctly operate those mechanisms. But otherwise, if there is adequate oil volume there is adequate lubrication as long as the actual viscosity results in an adequate MOFT. That is why "oil pressure does not equal lubrication" when the oil volume supply is basically constant due to the PD oil pump. An engine could have relatively low oil pressure but still be supplying a ton of volume. Only when the oil viscosity it too low to provide an adequate MOFT is when lubrication is failing. Yes, lower oil pressure means the viscosity is lower, but oil pressure can't be used to determine what the MOFT might be due to the actual oil viscosity between moving parts.

 

[Kestas]

Correct me if I’m wrong, but isn’t that one picture of the cam showing a chunk that has spalled out? Not sure how lifters could cause that, it looks more likely to be really poor metallurgy or hardening of the cam.

Reread my post on the first page.