What does a failing 603 vacuum pump sound like?
 

Rattly? Clanky?

Yes, out of the ordinary. Like a constant tapping and a loose sound. At least for me.

This morning, I was fiddling with the SDL's monovalve and realized that there was a LOT of noise coming from the front of the engine...very directional sound too ie: with the hood closed you can't really detect it but, open the hood and stand on the driver's side and there's a distinct 'rattle' that is radiating from either the timing chain, vacuum pump or belt tensioner.

Color me concerned.

I read Sixto's description of the belt tensioner failure (see #4 in ths thread) and what he describes is a lot like the sound I'm hearing. When I get home I'm going to release the belt tension and start the engine to see if that eliminates the noise.

Meanwhile, how do you identify the new and old vacuum pumps? I've searched the forum and cannot find anything conculsive.

It has something to do with the number of screws on the front, or cover, or something like that. I know I've read it here somewhere.

See post #4 of this thread:

http://www.peachparts.com/shopforum/diesel-discussion/161817-300d-engine-vacuum-pump-w124.html?highlight=updated



http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1VK01GHCF1YU1AWYEP&year=1987&make=MB&model=300-SDL-001&category=D&part=Diesel+Vacuum+Pump

I read that part about hex bolts. But, do you think they mean "cap head screws"? That is what the replacement part in the picture has on it.

Old style has a smooth cover. New has the four screws on the top.

Don't pay $400 for one, that's a MONSTER mark up.

:eek: :eek: they mark that thing up double what its worth!

Sorry to hear your Vac Pump is sounding noisy, if you pin point the sound to it and replace it before it disintegrates, you will have saved a lot of $$!

Anybody have a pic of the old style, for comparison......

I have an old one somewhere around here, but basically it has no bolts on top at all, the lips around top is crimped over at a few places thats all, O/W they have the same general appearance.

Pretty much.

Thanks!!

I'm pretty sure that mine has some sort of fasteners on the cover — I'll shoot a pic in the morning. I'll bet this eventually turns out to be the belt tensioner.

Could be the tensioner shock too, that makes a ton of noise when taking a dump.

Thanks all!!

I'm reasonably confident that (1) I have the later style vacuum pump and (2) the noise is caused by a combination of worn parts in the belt idler/tensioner assembly.

Here's the pump that's on the car:

It is the later style pump, right?

The idler dampner has loose ends (the Heim joints are worn) and the idler pully is running at a slight angle in relation to the belt. The belt looks OK so far.

Today, I'll order all the parts needed to replace the idler assembly.