SOHC chain tensiners

[gw33gp]

SOHC chain tensioners

My 4.0 SOHC engine has 161,000 miles on it and is running very well with no indication of timing chain problems.

I recently came across some information about the timing chain tensioners getting weak with age and it was a good idea to change them at high mileage. It looks like a fairly easy replacement as it can be done without removing the engine and only takes around 3 hours to do both front and rear. The cost of the parts is not cheap but not all that expensive at around $100 if it can improve the life of the chain guides.

It is said the tensioners stabilize the chain guides and reduce vibrations that could cause increased wear. Weak chain tensioners will result in increased vibration and more wear on the chain guides. My main concern is that new tensioners could cause more pressure on the chain guides and possibly cause more wear.

Anybody have any experience or thoughts on this?

 

[Diesel_brad]

Dont fix what aint broke. Until it starts making noise, there is no need to replace them

 

[gw33gp]

I understand that approach but believe in good maintenance also.

If I strictly followed the "don't fix what aint broke" approach, I would wait until the rods are knocking to change oil. I am not trying to belittle your advice but there is a limit to that old saying.

 

[Diesel_brad]

Then put new ones in. Why bother asking

 

[bmerr98]

I gotta go with Brad on this one. Nobody is promoting a "run to fail" maintenance approach. Just saying if there's no indication of wear (like rattling noises), and it's not something covered by routine maintenance (like oil changes), I wouldn't fool with it. If you choose to, it's your truck and your wallet - have at it.

But what's the sense in asking for people's thoughts on an issue and then talking to them like they're some kind of moron who doesn't know the limits of "don't fix what isn't broken" ?

 

[gw33gp]

Sorry that you guys interpreted my reply as responding to a moron. I use extremes to help evaluate and explain things. Since you don't know my approach, you are offended. No offense was intended and I apologize for my lack of tact.

I guess I will have to go with the original technical information I came across that recommended changing the tensioners at high mileage.

 

[BRUTUS_T_HOG]

If it puts your mind at ease then go ahead and replace it.

Kind of like replacing a timing belt on a valve bender before it breaks.

If it was me I wouldn't worry about it if you've been good on your oil changes

 

[gw33gp]

I like your analogy. The tensioners are probably quite not as serious but it does compare as a mechanical maintenance item.

 

[hilltopfarm]

gw33gp: Hate to tell you this, but you would have to remove your engine in order to do a proper job. There are timing chains in the front and the back of the engine. A lot of times it is the rear guides that go. It would probably just be easier to pull the engine to do the job anyway. If you have the time to pull it and do the timing chain job now, it may be a good time as opposed to later when you don't have the time BTW: Nice looking truck!

I just replaced my engine on my 03' at 134K because of timing tensioner failure in both the rear and front and other issues, the last owner did not take good care of the truck at all (oil change 7500 mile interval, etc...) I plan to change the oil at 4K or 4.5K and run synthetic. Hopefully that gets me to 200K! Also hopefully the new engine has the updated timing components like the remanufacturer says it does...

Heres a view of the front of my old engine FYI:

Here is what happened to the rear guide:

Here is what its supposed to look like:

Picture of the locations of the chains (Front of the engine is pointing UP)

Hope that helps!!

 

[gw33gp]

That is good information. I am not planning on replacing the guides at this time. I am considering replacing the spring loaded tensioners that snug up the guides to the chains. These tensioners can be replaced without removing the engine. They are screwed into the block or cover (maybe the head) and are accessible without removing the engine.

It seems they can wear and provide less tension which results in more vibration causing damage to the guides. I don't know how true this is but at around $100 may be worth it if it extends the life of the guides.

 

[hilltopfarm]

All I can say is that I have been told that the springs wear on those tensioners allowing more movement. However the springs in the engine pictured above were just as tight as the new one...Also from what I can tell the tensioners are hydraulically activated the springs are just there to provide some tension during startup when there is no oil pressure.

To test out my theory, I took an air compressor and applied air to the hole in the top of the tensioner, the tensioner instantly became hard, I could no longer push it in. So I almost think that most of the wear on the guides are due to no oil pressure when the engine is first started...thus no tension. My conclusion is that an oil accumulator would prevent this from occurring by providing the necessary tension at startup.

Any Thoughts??

BTW: If you do end up replacing the tensioners, torquing them to the right spec is critical to ensuring that they do not leak

 

[gw33gp]

That is my understanding of how the tensioners work also. The springs just provide pressure until the oil pressure builds up. An oil accumulator like an Accusump would be a great idea to provide oil pressure at start up. It might be difficult to find a place for it though.

Thank you for describing the strength off the old tensioner compared to the new one. This may be an indicator that the tensioners may not need to be replaced at high mileage. Maybe I should remove the most accessible one to check the spring strength before ordering new ones.