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Re: Balance chain gears Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 6 Feb 2001 11:10:55
In Reply to: Balance chain gears, Kevin H, Mon, 5 Feb 2001 21:29:32 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Do you have a 2.3 or 2.0L engine? Both were available in the 9000s in '90, depending on when the car was built in the model year.
The 2.0 has no balance shafts, so I'll assume you have the 2.3. There are reports of problems with the balance shaft chain and sprockets wearing. The timing cover needs to be removed to access the balance shaft chains. If the chains are replaced, it makes sense to replace the sprockets at the same time. Unfortunately, I don't know a good way to troubleshoot balance shaft chains.
However, you speak of noise from the timing cover. You'll find the timing chain there, for both the 2.3 and 2.0 cars. The balance shafts are much lower down on the engine.
A few questions - do you hear the noise only when the car is cold, or all the time? Is it a tick-tick-tick, or a clatter, like spoons rattling around in a tin can?
First off, there are A LOT of reasons for a noisy top end, and many of them are minor. Don't immediately assume you need a new timing chain on noise alone.
It's very common for Saab engines to be rattly when cold. This is normal as the hydraulic lifters pump up pressure. A 'lazy' lifter might take a minute or two to get to pressure, and can make a racket.
A ticking noise from the engine at idle may just be the sound of the fuel injectors. They open and close abruptly, and that sends little shock waves down the metal fuel rail. There is a fuel rail damper at the end of the rail just to help reduce this sound, but they tend to fail. I like to use a piece of rubber hose with one end held up to my ear as a stethescope to isolate noises.
Timing chains do break (as in Mark O's case), but it's rare. Unless the timing chain sounds like a china closet collapsing, never replace a timing chain on sound alone (or even then). Many mechanics will listen to your engine and pronouce the chain bad - why not - it's a $1000 job, and if the chain turns out not to be the problem, the work is still done.
If you are worried about the sound of the timing chain, you can check it. Remove the valve cover and inspect the chain for wear visually. Turn the engine over to TDC of cylinder #1 and check the alignment marks on the cams against the marks on the cam bearing blocks. If the marks line up, the chain hasn't stretched. If the chain looks to be in good shape - no abnormal wear, chips, etc, then it's probably fine. If you really feel flush, replace the chain tensioner, which is a $50 unit that can be easily replaced (in a 9000) from outside the engine. Spend another $25 and replace the upper chain guide- it's the rubber block on the underside of the valve cover. It dries out and shrinks over time, and causes the chain to rattle. You'll need a new valve cover gasket.
I would never spend the money for replacing a timing chain without inspecting it first. The labor to pull the valve cover is minimal, and if the chain needs replacing, has to be done anyway.
Good luck!
, Tue, 6 Feb 2001 11:10:55 <-- Viewing This Message
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