Thanks ALL for the advice on 350SDL engine noise. I'll take an old stethoscope to the motor tomorrow to isolate the noise. I’m confident that it’s not the bottom end and not related to the belt tensioner.

Incidentally, when I changed the belt a few months back, I ended up with, at first, air conditioning problems, then an overheating issue and finally power steering problems. After double and triple checking the Gate’s belt from NAPA, I finally purchased one from MB and it solved all the problems at once. It seems that the Gate’s belt was not “tacky” enough to grip all the accessories without slippage. To be safe, the tensioner was inspected and the shock and spring replaced. To this day the tensioner is parallel to the belt with no wobble.

The cracking sounds like it could be coming from a sticky injector but the engine runs very smooth at idle and runs hard in gear.

Since I purchased the car in May with 118K mikes, I have put over 25K miles on it mostly at 80 mph (Florida highways). Top speed so far: 125 with lots of pedal left.

Lovin’ her until she blows…

Mav