W202 Engine noise

Rob_C180

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My 1996 C180 auto has developed an engine noise over the past couple of months. I’ve changed the water pump, aux belt tensioner and the shock (all of which needed replacing) and still it persists.

The noise sounds like a tapping which you would expect from the likes of a noisy injector or tappets and is consistent with engine revs but only heard when the engine is under load not at idle. It’s there when the engine is cold all through the rev range but when it reaches running temp its only audible over 4k rpm.

The funny thing is that it goes away when driving in the wet???

A couple of other problems I have is a rough tickover which if left idling for any length of time turns into similar symptoms you would expect from only firing on 3 cylinders. This is cured by a quick restart. This also leads on to a lack of power when trying to pull away which again is remedied by using the kick down.

1. What’s the problem?
2. Does anybody think this is all related?
 

lackofgrip

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i have the tickover problem but only when cold, its in for the service on tuesday too. thinking its the spark plugs.
 

Uncle Benz

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I know this sounds stupid, but have you changed the belt itself?? A dry old belt can often make a tapping sound...
 

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