Timing chain replacement

[MikeW]

Originally posted by Zedrally

So we could conclude that it was not the chain or tensioner or cam sproket that caused this directly.

In fact, it was in-correct assembly and no chain or tensioner replacement was neccesary.

Absolutely. I wasn't claiming that this would normally happen in the normal course of action. This is just an example of the bad results of a failure in this area.

[MikeW]

Originally posted by Zedrally

Anyone with a FSM handy?

My FSM (1972) doesn't even list a timing chain replacement interval. I know that timing belts in modern cars tend to be replaced at 60,000 miles but I suspect many go way over that due to owner neglect. I would think that the chain should last much longer than that.

[Bambikiller240]

Originally posted by Zedrally

So we could conclude that it was not the chain or tensioner or cam sproket that caused this directly.

In fact, it was in-correct assembly and no chain or tensioner replacement was neccesary.

EDIT: Disregard post, I missed reading MikeW's post describing the failure circumstances.

[Bambikiller240]

Originally posted by Zedrally

In my opinion chain strech would cause mis-timing which could be adjusted on the cam sprocket, obviously there must be a factory life, and this is what the original question was.

You can adjust the cam gear to advance cam timing relative to crank timing, but AFAIK, the only thing that takes up "stretch" is the tensioner. The tensioner is much more likey to fail than the chain is to stretch to the point of causing valves to kiss pistons. Now if the chain breaks............................

[beandip]

One thing that enters in to this is high RPM . This will add stress to the chain and in a big way to the surface of the tensioner. So in addition of age this can cause failure . Constant rpm will have a positive effect here as well , so an engine driven on freeways at constant speed or long distances will show less wear for the miles driven. This is why it is so difficult to predict the life of any engine or component . My 2cts Gary

[sblake01]

Remember that Mike W said that he didn't properly wedge the chain. His tensioner was probably wedged inside the cover no longer riding on the spring which would explain the deep grooves and then finally moved out of position allowing the chain to flex and you can see the results of that in his pictures.

[Bambikiller240]

Originally posted by sblake01

Remember that Mike W said that he didn't properly wedge the chain. His tensioner was probably wedged inside the cover no longer riding on the spring which would explain the deep grooves and then finally moved out of position allowing the chain to flex and you can see the results of that in his pictures.

Thanks for pointing that out, Stephen. Somehow, I missed that post in trying to catch up on the thread after work yesterday.

[sblake01]

Originally posted by Bambikiller240

Thanks for pointing that out, Stephen. Somehow, I missed that post in trying to catch up on the thread after work yesterday.

It comes from personal experience. Did that years ago to my first 510.:stupid:

[Ed]

On my first engine I noticed that the timing chain had little "rollers". These rollers are what engage with the sprocket teeth. Some of these rollers were broken on my chain. I would think that if enough of these rollers were to break you could have some terminal results.

[MikeW]

Originally posted by sblake01

It comes from personal experience. Did that years ago to my first 510.:stupid:

I'm glad I'm not the only one. Keep in mind that I did wedge in a piece of wood as specified in the FSM. However, it must have not been quite tight enough and therefore let the tensioner pop out just enough to make the chain too tight to get the sprocket back on the cam.