Vacuum Pump Implosion? W115 240D - PeachParts Mercedes-Benz Forum

diametricalbenz · #1 05-19-2006, 02:09 AM

I was driving home in the W115 240D on the freeway and noticed some louder than usual engine noises. All of the sudden when traffic built up I pressed down on the brakes and no vaccum boost was available! I was going through south central and the engine was still running and there was oil pressure so I pushed on.

When I got home I found that the whole front end of the vacuum pump had cracked from top to bottom.

Has anyone seen something like this?

I guess it's metal fatigue from 32 years of operation

#2 05-19-2006, 02:37 AM

Well, when you figure 1 pulse per engine rotation...

3000rpm highway cruise for 1 hour. That's 180,000 pumps! I can't even imagine how many times it pumps over 200,000+ miles!

Amazing that they don't break sooner.

Diesel Giant · #3 05-19-2006, 07:50 AM

Oh I have never seen a pump do that. I bet the rocker arm assembly failed.

#4 05-19-2006, 08:40 AM

Take a look at the photos of mine in post #24:

Stuck in NE - vacuum pump failed

Most likely the pump failed and broke the casing. You don't want to drive it until you replace the pump and take a look in the oil pan for loose parts. Hopefully, you will be luckier than I was.

diametricalbenz · #5 05-19-2006, 02:22 PM

Quote:

Originally Posted by Craig

Take a look at the photos of mine in post #24:

Stuck in NE - vacuum pump failed

Most likely the pump failed and broke the casing. You don't want to drive it until you replace the pump and take a look in the oil pan for loose parts.
Hopefully, you will be luckier than I was.

Craig, your vacuum pump looked much worse than mine!

It would seem that the pump failed and hammered away at the case. I am interested to know what happened. When I get the pump back I will post some follow up pictures. I hope the pump from the 1979 240D will fit on it!

Wow am I happy that I upgraded my AAA membership to Plus status 3 weeks ago! The memership fees paid for itself in one tow.

#6 05-19-2006, 02:47 PM

Quote:

Originally Posted by diametricalbenz

Craig, your vacuum pump looked much worse than mine!

It would seem that the pump failed and hammered away at the case. I am interested to know what happened. When I get the pump back I will post some follow up pictures. I hope the pump from the 1979 240D will fit on it!

Wow am I happy that I upgraded my AAA membership to Plus status 3 weeks ago! The memership fees paid for itself in one tow.

My whole ugly story is in the other thread, but you're correct, the pump let go at about 80 mph and caused a bunch of collateral damage. Hopefully yours didn't generate as much shrapnel, but I ended up with about 8 pieces of metal in the oil pan. It's probably cheaper to find a used pump that fits and rebuild it, than to buy a new one (about $500). If you were able to drive it home, you're probably OK, but I would still look in the pan.

diametricalbenz · #7 05-19-2006, 03:17 PM

Quote:

Originally Posted by Craig

My whole ugly story is in the other thread, but you're correct, the pump let go at about 80 mph and caused a bunch of collateral damage. Hopefully yours didn't generate as much shrapnel, but I ended up with about 8 pieces of metal in the oil pan. It's probably cheaper to find a used pump that fits and rebuild it, than to buy a new one (about $500). If you were able to drive it home, you're probably OK, but I would still look in the pan.

I'll have to read through it for tonight's evening reading since I am at work now.

I have noticed that my oil pressure is lower than normal after freeway cruising. I wonder if a piece broke off internally earlier and is restricting the oil pump. I guess pump breakage is just a degenerative resultant effect.

Worst case scenario, if it's bad, it's time to yank the 300D motor and drop it in!

t walgamuth · #8 05-20-2006, 02:55 PM

yeah, sounds like it is restricting your intake on the oil pump.

not good.

tom w