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Discussion Starter #1
Hello everyone.

I've been having troubles with a strange noise coming from the engine. Sounds like its coming from the front portion of the engine closer to the top. When i start the car in the cold, everythings fine. When the choke disengages, the engine starts to rattle. After about two minutes, i can hear something shut off and the noise quiets down a lot. You almost can't hear it anymore. Then when i apply a little bit of gas, you can hear it again. Disappears at about 1500 rpms. Ill upload a video tomorrow. Does anyone know what could be causing this?

Thanks in advance,
Joseph
 

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I can't tell for sure without hearing it but its most probably the belt tensioner shock.

Here is a thread that is very useful for replacing the belt tensioner shock, its quite easy and the part is under $30 from AutohausAZ.
http://www.benzworld.org/forums/w202-c-class/1302596-replacing-serpentine-belt-tensioner-shock-absorber.html

One way you can verify if it is the belt tensioner shock is when you hear the rattle, press firmly on the belt tensioner shock to see if the rattle quiets a bit, and if so then it is for sure the belt tensioner shock.

I had the same problem, my car sounded like a diesel, but after replacing the belt tensioner shock i haven't heard any rattle.
 

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Discussion Starter #3
Thank you for the quick reply.
I'll check into that. I'll still upload the video with the actual noise tomorrow, but that's probably the problem...
 

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In addition to the tensioner, also check the secondary air pump if your version has one since this problem seemed to quiet down after the warm up loop expired. 230k's don't have the secondary air pump (uses the kompressor instead), so I can't really advise you more.
 

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Discussion Starter #7
In addition to the tensioner, also check the secondary air pump if your version has one since this problem seemed to quiet down after the warm up loop expired. 230k's don't have the secondary air pump (uses the kompressor instead), so I can't really advise you more.


ok will do. Thanks
 

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My 230 (1998) sounds exactly like your car does at the beginning of the video. That slight ticking/diesel sound. It does not start making that grinding sound. Is this normal? Could it also have to do with the tensioner. Ways to check?

Thanks!
 

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DAMN! That engine sounds unhappy man...

Have you ruled out the timing chain? It sounds like its grinding internally at the chain.. Might need to replace it aswell as the guides..

Check to see also if the viscous fan / aux fans are not hitting their side walls..

what is the milage on this vehicle?
 

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The serpentine belt tensioner has hard plastic bushing which disintegrates and the bare bolt and tensioner end raddle, making motor sound like diesel.
Replace belt tensioner, cheap like $34 at AutohausAZ. Put a screw driver end on the top of tensioner and press down, should quite down. Be careful of the fan.

The high pitched sound is the Air pump, normal when cold to run for 1-2 minutes, they are noisy.
 
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