Vacuum pump
 

Last night the wife started her 2012 ML350 (Bluetec) in the driveway and I immediately heard a sharp knocking sound over and above the normal diesel noise. I immediately popped the hood and isolated it down to the vacuum pump. Putting my hand on the pump I could feel it rapping internally in time with the knocking sound. After about 3 minutes of idling, the knocking/rapping became intermittent, and at the 5 minute mark went away entirely.

Since it is the wife's daily driver I am not going to mess around and plan on ordering a new pump straight away. Anyone ever had to change one out or able to offer any tips? Lastly I know a dying vacuum pump can potentially destroy one of the older diesel engines (OM617, OM602, etc) Is it the same danger with the OM642? I ask as she may need to drive it for a few days until the new pump arrives.

Thanks

Just remove the 4 bolts , line up the shaft reinstall 1/2 hour job