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Old 12-02-2002, 04:53 PM
Posts: n/a
M116 Valve train- source of engine noise??

1982 380 SL 133K

I purchased this car with a terrible engine noise that sounded to me like a rod or wrist pin. Very pronounced hammer like noise upon start up that seemed to diminish with increasing engine speed (as in when I drove it home-9 miles). I thought the noise was just being covered up with all the other engine /driveline noises and that may have been true.

I finally was able to get the engine mounted on a stand over the long weekend. I removed the oilpan and cam covers. The previous owner had taken the car to an independent garage and they had diagnosed the noise as a bad rocker arm. They went through the valve train and supposedly changed out rocker arms (number unspecified by previous owner and he didn't have a bill at the time of sale). Whatever they did they didn't eliminate the noise and told the owner that they thought for sure it was the rocker arms.....

I made the mistake of assuming they had eliminated the valve train as the source of the noise (and believe me it is much louder that any valve train noise I have ever come across). I found it haed to believe it was a rod or wrist pin at that mileage, but knew anything was possible..

Today I took the time to go over the components in the valve train and noticed the exhaust rocker arm on #6 was sitting lower than any of the others. With the cam lobe pointed up I was able to move the rocker arm up and down 1/8". The valve clearance compenstor was not supporting the rocker arm. Notice how low the rocker arm on the right is sitting on the compensator. As indicated I can wiggle it around and the total movement up and down is 1/8".

So the questions have to be:

What has happened here? Obviously the previous owner was ripped off in that there is a problem with the rocker arm.

The important question has to be would this tremendous amount of clearance be responsible for the loud hammering I was experiencing??

What would be the procedure for repairing this problem? Remove the cam , rocker arm and compensating device? Replace compensating device and rocker arm with new and adjust? Any special tools or procedures in replacement of compensating device(I'm new to Mercedes).

Sorry for the long post but I wanted to lay the whole deal out as much as possible. Thanks for any input, advice, or suggestions.

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M116 Valve train- source of engine noise??-valve2.jpg  
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