Timing chain woes

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Originally Posted By: morris
didnt some engines in the 30s-40s have only gears? iam not THAT old.


I don't have any experience with those, but for almost any Chevy or Chrysler pushrod V8 you can get an aftermarket gear only setup. Is it worth the bother? Probably not unless you're going to replace the chain anyway and don't mind a little bit of whining noise.
 
A lot of diesels have gears, and also drive the injector pump off those gears. You cant hear the whine over the clatter and they dont spin as high as a gasser, anyway.
 
Some Pre WWII overhead cam British cars, had a vertical drive shaft with bevel gears at each end, to drive the Camshaft.

There was a famous multicam Duesenberg or Hispano suiza that had a very elaborate chain of gears driving the cams.

I'll try and find a link.

It may have been this Miller that I was thinking of:
http://www.google.ca/imgres?q=duesenberg+cam+drive&start=111&um=1&hl=en&client=firefox-a&sa=N&rls=org.mozilla:en-US:official&biw=1440&bih=737&tbm=isch&tbnid=mSYpDXevsW136M:&imgrefurl=http://www.classic-car-history.com/indy-500-history-1920-1929.htm&docid=YMEelTaRFMBdBM&imgurl=http://www.classic-car-history.com/classic%252520motorsports%252520pictures/vintage%252520indy%252520500%252520cars/indy-500-junior-special-gear-drives.jpg&w=382&h=600&ei=cypkT6rTCuaXiALh4fyiDw&zoom=1&iact=rc&dur=545&sig=103022012415316701229&page=6&tbnh=171&tbnw=92&ndsp=23&ved=1t:429,r:8,s:111&tx=59&ty=65
 
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Originally Posted By: Donald
The good old timing chains in a GM small block V8. Anyone ever heard of a timing chain back then?


That's because they're as short as can be. The cam is directly above the crank, couldn't be any shorter.

In modern engines, they're running all over. Way up to the cams, having to be guided for clearance issues, with guides that are bound to wear out.

GM is/was having problems with their 3.6 engine. Having to replace them in low mileage vehicles. I have that engine in my Traverse, and apparently I have to wait until the CEL comes on before GM will replace the chains.
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Originally Posted By: morris
didnt some engines in the 30s-40s have only gears? iam not THAT old.


As I understand it, the Ford 300 I-6 had timing gears even in the '90s. I think the crank gear was metal and the camshaft gear was nylon. Quiet and durable, at least in my experience.
 
Originally Posted By: Rock_Hudstone
Originally Posted By: Donald
The good old timing chains in a GM small block V8. Anyone ever heard of a timing chain back then?

Yes, many GM engines for years had timing sets with nylon coated cam gears which were notorious for the teeth breaking off with age and mileage.

If things got bad enough the broken teeth would clog the oil pickup and seize the engine. Don't ask me how I know.


The 2.5 Iron duke in my S-10 has timing gears, metal on crank, nylon on cam. It's not a matter of if they fail, it's when. Had to replace mine, and they're not set up for any sort of easy remove and re-install. Apparently GM thought they'd last forever..
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The Ford 2.8 V6 of the '80s had timing gears.

The Ford 4.0 SOHC V6 had timing chain issues when first introduced. And it had about 3 or 4 chains, one of them at the back of the engine. Replacing that one required either removing the transmission or removing the engine. The engine was introduced in 1997 and issues up until around 2003. The later ones don't have any problems. I have one in my 06 Ranger and I'm confident it'll go well over 250k without any issues.

And I still prefer chains over belts.
 
Originally Posted By: MarkM66
Originally Posted By: Rock_Hudstone
Donald said:
Yes, many GM engines for years had timing sets with nylon coated cam gears which were notorious for the teeth breaking off with age and mileage.

If things got bad enough the broken teeth would clog the oil pickup and seize the engine. Don't ask me how I know.

The 2.5 Iron duke in my S-10 has timing gears, metal on crank, nylon on cam. It's not a matter of if they fail, it's when. Had to replace mine, and they're not set up for any sort of easy remove and re-install. Apparently GM thought they'd last forever..
crazy.gif


Well, they typically fail north of 100,000 miles, which years ago, was about the life span of the average vehicle as the engines would start burning oil or rust out by then.

Also, cars were less expensive back then, people had more disposable income and didn't have to drive their old cars forever, just trade-in on a new model or low mile used.
 
The Germans went threw this in the 70's and 80's. Owners of old Mercedes M116 V8's know all about doing chains and guides at 100k.

Fast forward to this century though and a chain even a very long one for a dual overhead cam V8 should never need service.

I guess the other companies haven't quite figured it out yet.
 
I've also wondered why Toyota went from timing chains to belts in the 90's, then back to chains now.

The R 4cyl has timing chains (obsolete)
The VZ 6 cyl engines has timing belts (ob)
The UZ 8 cyl engines has timing belts (ob)
The MZ 6 cyl engines has timing belts (ob)
The GR 6 cyl engines has timing chains (current)
The UR 8 cyl engines has timing chains (current)
 
The R-series engines were odd for Toyota. At the time of the 8R, 18R, and 20R, most Toyota engines were OHV. The, P-series, K-series, T-series, 4 cylinders and F-series 6 cylinders (which replaced the copy of the Chevrolet Stovebolt 6 Toyota was using) were all OHV. IIRC, R-series engines prior to the 8R were OHV so a timing chain seems to be more natural. They wouldn't have to design a new crank gear.
 
I don't think a crank gear would hold tem back.

It all depends where you want to place the Cam. After a certain spacing, it's better to use a belt or chain than Big or multiple gears.
 
Early 2.2L Saturn built ECOTEC's(prior to May 2003)and Chevrolet ECOTEC's through 2004 had chain issues due to low oil lubrication at idle, caused they chain to snap from lack of lubrication. 1998-early 2002 Ford 4.0L SOHC had tensioner/guide issues as well. I've never seen/heard of chain issues on the 4.6L Ford engines. 2.2L Cheverolet OHV engines suffered from bad tensioners although like the 4.0L SOHC they gave the owners plenty of warning noises before they would jump timing. The trick with OHC timing chain engines is regular short OCIs. VVT engines are also sensitive to OCIs as well, long OCIs tend to cause issues with electro-hydraulic valves that control these systems.
 
My old Honda Interceptor had a bunch of gears in the heads. Made a great noise.

I needed to replace a chain tensioner in a 4-cyl BMW once, at 160k. But otherwise BMW chains seem to easily last the life of the engine.
 
Originally Posted By: Hokiefyd
Originally Posted By: morris
didnt some engines in the 30s-40s have only gears? iam not THAT old.


As I understand it, the Ford 300 I-6 had timing gears even in the '90s. I think the crank gear was metal and the camshaft gear was nylon. Quiet and durable, at least in my experience.


Yep my i-6 has the gears. Nylon and steel. Mine has 300,000km on the origional set. They never changed the design from the day it was made till the last day it came in the truck (the gears). They supposedly use them for generators and pumps. I dont know if someone else makes the motor now or if they were using up stock but definatley a cool engine. They are fairly loud in the noise department but still cool. Id say the closest thing to a diesel that runs on gas.

I think manufacturers started using plastic stuff for quieter operation even if it didnt last as long. You have to admit a 2011 anything is sure alot quieter and smoother than a 19xx anything. simplicity seems to be the most dependable choice in an engine but nowadays an engine is built to fit in a car not chosen from a list with 4 different engines. Like the 60's to 80's Ive seen cars that could have had a 6 cyl, small block or even a big block in the same car.

I think emmisions and size have a big effect on what goes into an engine. If you look on the side of my 6-cyl it has those rectangular plates that hide the pushrods. You will never see that on a new car. I know there are very few pushrod engines out there but my versa looks like someone had to chisel an engine from a block of aluminum. The is no symmetrical parts on it whatsoever. Which leads me to believe parts that are weird shaped have to be made out of different material and have to preform differently. Plus now we have crazy DOHC engines that the cams are two feet above the crank. So you would need 15 gears to get the power up there. and you would neet two sets of the gears.

I had to replace the timing belt on my old mazda mpv i had with the 3.0 v-6. it was a DOHC v-6 that was a day job to get all the stuff off the front of the engine and remove part of the cooling system so i could get remotely close to the front. I thankfully put an e-fan on instead of the clutch fan so i had more room. It must have been a 4' long belt it was crazy. I even had one cam off a tooth the first time so i had to redo it again.
 
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Horrors of timing belt engines?
I LIKE belts. External for easy changing and a very reliable system.
Chains, gear, guides, tensioners can and do go bad in chain type cam systems. And they are almost always harder and more involved to work on.
 
Originally Posted By: mechtech2
Horrors of timing belt engines?
I LIKE belts. External for easy changing and a very reliable system.
Chains, gear, guides, tensioners can and do go bad in chain type cam systems. And they are almost always harder and more involved to work on.


Yeah, but chains and their components don't ALWAYS have to be replaced. Most engines will run forever without the timing equipment ever needing to be touched. If you have a belt however, it WILL need to be changed, usually every 60-90k miles And if you don't, on any modern engine if that belt breaks, you are toast.
 
Originally Posted By: Nick R
Originally Posted By: mechtech2
Horrors of timing belt engines?
I LIKE belts. External for easy changing and a very reliable system.
Chains, gear, guides, tensioners can and do go bad in chain type cam systems. And they are almost always harder and more involved to work on.


Yeah, but chains and their components don't ALWAYS have to be replaced. Most engines will run forever without the timing equipment ever needing to be touched. If you have a belt however, it WILL need to be changed, usually every 60-90k miles And if you don't, on any modern engine if that belt breaks, you are toast.

Not all modern engines are of the interference type.

However, I still prefer timing chains, because a timing chain often gives warning signs of failure, unlike belts, which can simply go snap in some cases.
 
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