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Discussion Starter · #1 ·
Hey guys…just recently since it started to get cold (below freezing temperatures), my engine has been running louder than before. It’s a ‘94 900 Turbo with 199k km. It sounds as if there would be a hole in the muffler, but the sound is coming from the engine bay. I can also feel stronger vibrations in the gear shift knob, particularly at rpm’s greater than 2500. And this happens even after the engine has warmed up. Does anyone know if this is normal during cold outdoor temperatures? Or could it be due to an actual leak somewhere in the exhaust? I appreciate any feedback. I've also heard from some people say that they're cars run louder when they put in a K&N air filter, which I have one. Could that be it?
 

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With that kind of mileage, you replacement exhaust may be due for replacement.

Check your engine mounts.

I do not recommend the K and N air filter, the filtration is not that good.
The "noise " I do not know about..
 

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PauL13 said:
...stronger vibrations in the gear shift knob, particularly at rpm’s greater than 2500...
that seem odd, usually it is the other way around, if you have a source of vibration, it becomes stronger and more noticeable at low rpm and at idle, especially through the manual shift knob.

The most obvious source of exhaust noise in the engine bay is a rusted out flex section in the turbo downpipe.
 

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Discussion Starter · #5 ·
I've also noticed that during idle, I can hear the valves and lifters "clatter". Could all this engine noise be due to a worn out timing chain? Does anyone know when is the best time to replace the timing chain?
 

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There is a difference between lifter noise and chain noise, but they can have a common cause, poor oil circulation, especially in winter.

You typically notice the noise in winter, because it takes longer for the engine to warm up and for the oil to circulate. The noise first shows up during cold idle, then during warm idle, and so on...

The time to replace the timing chain is when the timing chain tensioner is no longer able to take up slack from excessive wear on the chain and chain guides. Usually the plastic chain guides are replaced along with the timing chain. Sometimes, the sprockets have to be replaced too.

TC Tensioner Inspection
 
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