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Extreme vibration - checking balance chain?

My 1999 Saab 9-5 was running great. It has 141K miles. One day I pulled out of a parking lot and the engine rumbled loudly on acceleration and the car shook. I then noticed at cruising speed (~45 mph) it was much less noticeable and when I take my foot off the accelerator it gets much worse and the whole car shakes. My mechanic checked and says the motor mounts need replacing which might fix it and he is concerned about the balance chain used by Saabs. Is there anyway to diagnose any chain issues without having to take apart the engine or should I just have the chain replaced?

Which engine does your 9-5 have?

2.3L 4 cyclinder.

Check that you don’t have a driveshaft (half-shaft) flopping around due to a failed CV joint…

If it was the engine, it would vibrate with the car stopped as you slowly rev the engine…

A timing chain going nad won’t rumble, it’ll rattle, and as Caddyman said it can be verified while at a standstill by simply putting your head under the hood and revving the engine manually using the accelerator linkage.

Motor mounts can cause your symptoms. But before spending the money I’d either have him show you or get a second opinion.

And, as Caddyman said, get the CV joints checked out too. They can also cause your symptoms, and they’re common replacement items on aging vehicles.

Thanks for the advice, there is little sound coming from the chain, but there is also a definite rumble when stopped and revving the engine. I have seen the mounts and they are shot. The fluid filled one is dry. If I understand you correctly the timing chain won’t cause engine rumbling and shaking? That would be nice to know and would narrow down the options.