new motor, new noise
 

I recently had a used motor installed in my 93 300D, the old one was slam wore out. the used motor I had installed worked great BUT I have a clack or knock coming from it at all RPMs. To give you an idea how loud, if I turn the AC on High or crank the radio you can't hear it nor at highway speeds. Acceleration is according to spec, oil pressure pegged at 3 when driving and 1.5 to 2 @ idle when warmed up. Temp is normal. Mileage is as advertised. Starts with a touch of the key. I installed new lifters, no change at all, did a LUBRO MOLY purge of the injectors and pump IAW the instructions, no change, ran on straight Extra Virgin Olive Oil since I had the lines out anyway. No change in the knock noise at all. As I've said I've run this on Dino D, Bio D and VO with no change in performance. I think this motor would run on cat "P" but this noise is bugging the hell outta me.

What else can make this noise? Vacuum pump?

That would be the most obvious place to start looking for your noise, but I would rule that out soon if I were you!

Get a few feet of small diameter hose, put one end up to / into your ear canal, move the other end around the engine until you isolate the source of the noise.

Check the o-rings on the oil filter center tube - there are two small o-rings at the bottom, if left too long they get hard as a rock. If they degrade too much, strange noises can result. I can't explain why, but one poster just about went crazy trying to figure out a weird noise and replacing those o-rings fixed the noise.

A belt damper with worn end bushings can make a knocking noise. Does prying the upper attachment away from the head quiet the knocking?

Sixto
MB-less

I'll check all of those, thanks

Clacking? Any possibility the injectors are worn? Injectors are only good for so long.

Does the noise get louder if you come to a stop sign and then accelerate?

Use a long screwdriver and listen.

Sorry you can't catch a break with these engines. :P

no change in volume, I'm going to change the injectors just because. I have a new set in my tool box and got practice in with the old motor. :mad:

What weight oil are you using?

15w40