I have a '93 300D 2.5 turbo and my mechanic told me that he believes the injection pump is going out. He said that hears a noise that may be either the lower or upper bearings in the injection pump and that there is a also a loss of power at higher rpm's. He also said that if it is the upper bearing it would be okay to leave alone but if it is the lower bearing it could be real trouble (due to engine timing issues?). It seems to me that the car is running nice. I don't "race" the engine so I haven't noticed any power losses. This is a really expensive job, so I wanted some advice. The last thing I want to do is neglect a part that could lead to major engine repair later. Does anyone have any suggestions for me?

Thanks,

Mike