W202 C240 Noisy Engine

[rorf]

One test to do is to remove the serpentine belt and run the engine for a short time - this will eliminate all noises associated with the pulleys, alternator, aircon, water pump and power steering. Crankshaft main pulleys can also have the rubber insert come adrift too.

If non of the above then the timing chain and tensioner.

 

[design guru]

I finally sorted the problem, turned out to be the water pump on its way out, finally changed it when it began to slowly leak. 3 hour job with my limited tool kit but saved a hell of a lot of money so its a great result. Fired up the car and it now purrs like a c240 should.