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This probably isn't going to make you feel better.. Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Wed, 24 Jan 2001 13:12:34
In Reply to: Re: Timing Chain Replacement, MA Younts, Wed, 24 Jan 2001 08:54:33 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Replacing timing chains in Saabs is a pet peeve of mine. Many mechanics will diagnose a bad timing chain based on noise. In my opinion, unless the timing chain sounds like a tin can full of spoons rolling down stairs, this is no reason to replace the timing chain.
Saabs tend to rattle at the top end normally. The rattle can come from many things - lifters, worn upper chain guide, loose chain tensioner. Yes, one reason may be a worn chain or sprockets. But to do an expensive repair based on noise alone is criminal. Of course, from the mechanic's point of view it's good.
If a timing belt is suspect, there is a way to inspect it. The valve cover is removed, and the engine is turned to TDC for cylinder #1. Alignment marks on the cam pillow blocks are checked against marks on the cam sprockets. This will tell you if the chain has stretched or jumped a tooth. If stretched, replace it. Next, inspect the chain for wear - do the same for the cam sprockets. If this inspection shows wear, replace the chain. If the chain looks good, then leave it be.
This inspection is about an hour and the price of a new valve cover gasket. I would do this before getting a chain replaced.
As an example, my wife's 9000 was in the shop for something, and the mechanic mentioned that the timing chain sounded like it was on its last legs. I said thank you, but it sounded normal to me. Three years and 35K miles later I pulled the valve cover to replace a leaky valve cover gasket. I inspected the chain per above, and it showed to be in fine shape (car at 130K). I did, however, also replace the upper chain guide, which mounts to the underside of the valve cover, and is therefore very accessable. $20 for a small piece of rubber. Interestingly, the engine was a lot quieter after replacing that one chain guide.
Now, if I had taken that mechanic's advice, I would have shelled out $1,000+, and when the car came back, it would be quieter. I would never have know the chain was fine, and that it was just an old chain guide.
Does that mean chains don't break, or never need replacement? No, they do. And considering your bad experience with the BMW, it's not unreasonable to pull the trigger faster on a chain problem. But with chains especially, it's always best to spend a few extra $$ troubleshooting the problem, rather than $$$$ fixing a problem that isn't there.
Good luck!
, Wed, 24 Jan 2001 08:20:17, Wed, 24 Jan 2001 13:12:34 <-- Viewing This Message
, Wed, 24 Jan 2001 09:36:18
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