2000 ML320 engine idler pulley
 

During my last warranty visit to the dealer they replaced the engine idler pulley. They indicated that it required replacement, however, I did not notice anything that was wrong. Since replacement, I now notice that there is a bearing noise that sings to me when the engine is operating over 2000 RPM. If I let off of the accelerator when doing highway speeds and engine speed of 2500 RPM the noise goes away as it would when you unload a bearing. Parking it in the garage and increasing engine speed while in "Park" shows the bearing noise is coming from the area of the idler pulley. I am thinking that the part is defective or they did not do a correct installation.

All I can say is that these new Mercedes are not like the old. Between my 2000 ML320 and my wife's 2003 C230K I am visiting the dealer 2-3 times per month on average. It will be extremely difficult for me to consider purchase of another new MB. By the way I also own a 1995 Mercedes C280 which hardly ever causes any issues and will definitely be a "keeper."

I woulda asked right away why they had to replace the belt tightener. You would think this would have been preceeded by some type of complaint. They didn't say anything about it, just "we replaced your belt tightener, pay up"?

I'd get it back there and have them look at it and voice your concern that it wasn't making this noise until they took it upon themselves to replace the tightener.

I know what you're saying about service problems. The weird thing is is that the belt tighteners they use now (the spring-loaded ones like "everyone else" has used since serpentine belts became common), rarely give problems. Not like the ones on the 103 engines for example.

Gilly

Gillly:

Thanks for your input! The belt tensioner was replaced under my last warranty visit so I did not "pay-up." Actually, I had requested that they replace the harmonic balancer which was a 00-00 suffixed part number and they instead replaced the belt tensioner. Another visit was required to finally replace the harmonic balancer. It seems that it is not all a Mercedes issue but also the quality of the service in the service departments in the dealerships. Kind of makes you just want to go out and buy the most realiable vehicle and "flip it" when it starts to become problematic.

It is hard to justify the hourly service charge when they can't seem to fix it right the FIRST time.