total loss of vacuum. 84 300td wagon - PeachParts Mercedes-Benz Forum

bro frank · #1 03-26-2008, 07:41 PM

so what's the best or most economical route. i currently have no vacuum at the vacuum pump.

do i rebuild. how hard is that?
can i update to electric vacuum pumps found on newer cars?

can i use the different style vacuum pumps found on my 300d or 240d? do they mount up the same?

oh yeah and how do you make them "live" longer?

kerry · #2 03-26-2008, 07:47 PM

Rebuilding is pretty easy. There are two different styles. The earlier type can be rebuilt without removing the whole pump. I rebuilt mine in less than an hour. The later style requires a homemade jig I think. There are pictures on the forum of the jig.
Easiest to rebuild and not switch in my opinion.

dmorrison · #3 03-27-2008, 11:08 AM

Quote:

Originally Posted by bro frank

so what's the best or most economical route. i currently have no vacuum at the vacuum pump.

do i rebuild. how hard is that?
can i update to electric vacuum pumps found on newer cars?

can i use the different style vacuum pumps found on my 300d or 240d? do they mount up the same?

oh yeah and how do you make them "live" longer?

Rebuild it, it's easier then rigging something.

It lasted 25 years, thats pretty long. How long do you need it to last???

Dave

bro frank · #4 03-28-2008, 08:00 PM

will the rebuild last 25 yrs?

will start pricing around

thanks

Diesel911 · #5 03-29-2008, 12:21 AM

Quote:

Originally Posted by kerry

Rebuilding is pretty easy. There are two different styles. The earlier type can be rebuilt without removing the whole pump. I rebuilt mine in less than an hour. The later style requires a homemade jig I think. There are pictures on the forum of the jig.
Easiest to rebuild and not switch in my opinion.

One of the sellers on Ebay sells the jig.

Diesel911 · #6 03-29-2008, 12:37 AM

Be sure it it the Vacuum pump that is causing the failure. (Be careful where your put your hands while the engine is running.) Disconnect the big vacuum line that goes to the brake booster at the vacuum pump and put your vacuum gauge there and test it. If no gauge put your thumb over the connector hole and see if you can feel any vacuum. If you are not getting vacuum from the connector try spraying some WD40 type stuff down the connector hole and see if it will clean out any gunk that might be blocking the valve that is down there.

The rebuild kit is sold in 2 parts. The part with the piston seal (if you have a piston type vacuum pump) and valves/O rings and stuff can be as low as $43 + shipping. The other (more expensive) kit has the mechanical parts parts like the rocker and the bearing.
Have you thought about taking it a part and having a look inside. It could be that the little valves are all gunked up and being held open. I might at least buy you some time till you decide what to do. A new pump is in the $300 range.
I took a look at mine and removed the power steering belt for easier access. The only problem I had is I sheared off 2 of the screws that held the cover onto the vacuum pump body. I needed to heat the rest to get them off. Since I did not have a new seal ring for the pump cover I used the old one with some silicone sealant when I assembled it. It is working fine.
Added later: The complete rebuild kit seals + rocker arm and relate parts at one place is $265 + shipping.

bro frank · #7 04-02-2008, 04:39 PM

first place i went when i lost vacuum was the big line. i diconnected it from the hard pipe. and thumbed it. very very slight vaccum. re-attached big line and isolated it from everything but brake booster. provides a little help when braking provided there's plenty of time between brakings.

looked under the hood of my 240 project and saw that it had the same style vac pump. plan to pull that engine any way and swap in another, so i may "steal the vacuum pump from it.

btw, are the 2 styles interchangable?

diesel911 i see you have a volvo. how does it compare to the benz?

JimFreeh · #8 04-02-2008, 05:06 PM

Quote:

Originally Posted by bro frank

first place i went when i lost vacuum was the big line. i diconnected it from the hard pipe. and thumbed it. very very slight vaccum. re-attached big line and isolated it from everything but brake booster. provides a little help when braking provided there's plenty of time between brakings.

looked under the hood of my 240 project and saw that it had the same style vac pump. plan to pull that engine any way and swap in another, so i may "steal the vacuum pump from it.

btw, are the 2 styles interchangable?

diesel911 i see you have a volvo. how does it compare to the benz?

My recollection is that the OM61X pumps all mount with a common pattern, but there is a variance between outlets.

Jim

tobybul · #9 04-11-2008, 10:06 AM

If vacuum pump is not working, will it reflect on the brake pedal feel as a quick way to check? Wouldn't it require it to step down harder if there is no vacuum assist?

Just wondering. I'm diagnosing a leak right now.

leathermang · #10 04-11-2008, 10:43 AM

Quote:

Originally Posted by tobybul

will it reflect on the brake pedal feel as a quick way to check? Wouldn't it require it to step down harder if there is no vacuum assist?

OH YES, BIG TIME... I was not ready for the effect and almost rolled through a stop sign before I braced to push as hard as it needed...

bro frank · #11 04-22-2008, 04:51 PM

found used vacuum pump and did swap. got vacuum while running but it's bleeding off fast. can't even get doors locked.

will try to diagnose it soon. but at least i have brakes.