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Quick question, so yesterday I was talking with my dad about cars (topic actually started as whether or not to sell my car while it still has some value in it to get a 900SE). The conversation quickly moved into some problems I think may pop up in the near future. I brought up my timing chain. Turns out the mechanic that he goes to owes him some pay from a general contracting thing my dad did for him, so if I'm uncomfortable will doing the timing chain, this guy will do it. My question is this: while doing the timing chain, I would think it prudent to replace the sprockets too, but with just a master link chain going in, only the camshaft sprockets would be accessable. Is it even worth replacing those two while leaving the lower timing chain sprocket as is? Do one of the two areas (lower sprocket or cam sprockets) wear more quickly?
 

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I suppose anything is possible, but I thought your timing chain tensioner was right where it should be, so what makes you suspect the sprockets?

The one on the crank is in contact with the chain over a much larger part of its circumference than on the upper, so the strain is distributed over more teeth. In theory it should wear less.

If the chain AND sprockets start to go, you would normally see a heavy wear mark on every other tooth. Eventually, the teeth get a slightly hook-like shape, from being worn more on one side than on the other, etc...
 

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PMI said:
I suppose anything is possible, but I thought your timing chain tensioner was right where it should be, so what makes you suspect the sprockets?
Its a paranoid fixation I have, and since I now know that the mechanic owes my family, I might just get the chain done now for free as preventative maintenance, and thought while at it, maybe do the accesable sprockets.
 

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My theory is that neither the sprocket nor the chain "wears - as such", but that the chain stretches, If every link increases in length by 0.01 mm or so, then the chain may be too long.

And if every pin wears by 0.0001 mm, then the chain is shot !

The manufacturer should use a much shorter chain or , better yet, use a Kevlar reinforced belt...

But if one chain outlasts two belts, and one can do the chain replacement successfully - then it is a tie....

Maybe GM does indeed have something with its "old-fashioned" pushrod 3.8 engine...
 

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Slaab4life said:
Its a paranoid fixation I have...
a mechanic that owes your family...perfect! What are you waiting for? :lol:

There are deserving SE Turbos, just waiting to turn someone's winter of discontent with pesky, low maintenance 900S models into a glorious summer of paranoia at full boost!
 
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