My wife drove into the drive way and complained of a noise. When I got home I noticed that the fan belt had shreaded. I diagramed the serpantine belt path and replaced with the correct belt. When I started the vehicle it is running very rough. When I installed the belt I disconectedm the tensioner. Once On I reattached. Is it possible that the belt is too tight? Should I have done any thing else? Comments and advise appreciated. Russell

If the belt was comming apart while being driven look for some vacuum lines that were knocked off.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

If your wife drove the car for any length of time with the fan belt gone, the car may have severely overheated. The head on these cars is aluminum and is known to crack under those conditions.

So, you may have a cracked head.

The tensioner keeps the belt fairly tight. There is a round hole in the arm that holds the tensioner pully. This is meant to be a place to insert a large screwdriver (or I think the tire lug wrench will fit) to put leverage on the arm. You should be able to move the tensioner arm this way, and that would be a good test to make sure it is moving properly.

But having said that, a belt that is too tight should not cause the engine to run roughly.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Also double check that you put the belt on correctly. It is possible to muscle it into place in the incorrect sequence.

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1987 300TD 231,000
#22, afterglow, plastic fan, euro lights, alternator upgrade, cluster housing update