Engine squeaks during startup (W124, 230E)
 

I'm experiencing a high pitch squeaking noise which occurs for 3 - 5 secs after startup. The noise disappears thereafter. Noticed some wear and tear in the drive belt and replaced it with a new one. The noise remains after changing the belt. Anyone knows the cause of the noise? pulley?

You may have a bad belt tensioner. If it is, you can't fix it, it has to be replaced.

My belt tensioner has been replaced eight mths back. I'm not so sure if the belt tensioner is the culprit as I normally detect some vibration noise when the tensioner goes bad. In this case, I'm not getting the usual noise associated with a bad tensioner.

Depending on year, air pump.

I'd also look at the idlers, fan bracket and coolant leaks. (seen a bunch of water pumps seep a little coolant on the belt when they sit awhile)



Joe