Mercedes: unusual engine noise, turbo bearings, noise question

Question
QUESTION: 1983 300cd turbo - starting to get a chattering noise up near front of engine.  Replaced water pump but nothing wrong with old one.  Still have the noise.  Could the bearings be failing in the turbo?  That's what it kind of sounds like.  Don't think it's a timing chain.  Engine is strong and good oil pressure.

ANSWER: Gene,
You may be on the right track. I would take a three foot length of hose. With one end held at my ear, I would take the other end and hold it at strategic place around the area of the suspected noise, to pin point the location.
The turbo bearings may be going out or you may have a crack in one of the the turbines. Or the timing change idler may be worn or loose.
If the trubo is involved it could cause major damage if the intake side loosed a part, as it could be injected to the intake.

Good Luck
Rob

---------- FOLLOW-UP ----------

QUESTION: Thanks Rob,

I'll follow your advice.  One other thing someone suggested is a bad bearing in the vacuum pump.  What do you think? Thank you so much for your help.  This is a great site.

Gene

Answer
Gene,
Yes the noise could also be generated by a bad vacuum pump bearing or alternator bearning, or any other accessory that is belt driven. If the pump has a singular belt you could remove the belt and see it the noise stops. You will need to isolate the noise before you can proceed.
Good Luck
Rob