Vacuum Pump Replacement - PeachParts Mercedes-Benz Forum

Harrison W · #1 01-27-2013, 05:54 PM

I have a 1987 300SDL (as listed in my signature) that runs fantastic. I've had no problems with loss of vacuum. Although I do think there is leak somewhere, as my climate control system is in a constant state of defrost. Anyways, the car runs great, no odd noises from the pump. But with over 265,000 miles on what appears to be the original pump, I'm starting to get a little cautious.

Is replacing the pump a very difficult job? Or is it even needed at this point if I'm not seeing any symptoms?

Pooka · #2 01-27-2013, 07:19 PM

Although not cheap, I have always heard that replacing the VP every 250,000 miles is a wise thing to do. So much is dependent on them there is no sense in waiting for them to fail.

I have never replaced one on that engine, but on the 2.5 as found in the early 90's 124's they are rather easy. Just be careful not to drop any of the bolts that hold it to the engine since they will lodge into something below, like the timing wheel/harmonic balancer, and can prevent the engine from turning over.

Just take it slow and easy. There is bound to be instructions on this on-line somewhere.

jay_bob · #3 01-27-2013, 08:20 PM

I somehow think you have a climate control problem unrelated to vacuum. If you had no vacuum your power brakes would not work.

If you go to w124-zone.com and register, that gets you access to the factory manuals and the excellent auto climate control troubleshooting procedures.

You definitely want to change the vac pump at that mileage. Failure will eat the engine.

bolzano · #4 01-27-2013, 08:30 PM

Quote:

Originally Posted by Harrison W

I have a 1987 300SDL.
Is replacing the pump a very difficult job? Or is it even needed at this point if I'm not seeing any symptoms?

Not too hard a job. Did it on 1985 300SD. Used new Pierberg made in Argentina. Pump is not the same part as SDL. Removed belts. Unbolted ps pump and removed. Did not disconnect hoses. Picture 1.

Cleaned out allen head bolts well to not strip out bolt heads. Unbolted Vac pump. Some of bolts hard to reach. Turned engine with socket wrench on crank bolt until stroke curve was as in picture so the roller on the vac pump would let the vac pump lie as close to the block as possible. Picture 2

Bolted new Vac pump on. Did not sit quite flat until it was bolted in because the stroke curve hits the roller in the pump.
Picture 3 new vac pump. Mine came with gasket. Enjoy.

Air&Road · #5 01-27-2013, 09:29 PM

Replacing the vac pump is not a big problem, but do not do it as a stab in the dark. Use a vac gauge and do a little analysis first.

jay_bob · #6 01-27-2013, 10:31 PM

He's got two different issues going on.

First is an OM603 with an old vac pump and he's north of 250k, that is a ticking time bomb all by itself even if his ACC worked perfectly. Yes the pump is over $400 but its way cheaper than an engine.

Second is an ACC in safe mode (max defrost). Lack of vacuum might be his problem but I suspect it is something else. Lack of power brakes and crappy shifting transmission would be happening if he totally lost vacuum and he would be noticing those much more than getting toasted by the defroster in safe mode.

Hence my recommendations to proactively replace his vac pump before it fails (ask vstech about how fast his SD went from DD to yard ornament), and then get hold of the FSM and troubleshoot his ACC system.

The later 126s adopted the newer generation ACC as on the 124s. The vacuum control system was simplified from the older system as found on older 126s and 123s. The old way had a multitude of discrete solenoid valves behind the dash all piped together with rubber hose jumpers. The new way uses a modular valve assembly with 1 input and 7 outputs so much less opportunity for leaks. You can also get to the multi valve assembly from the passenger lower dash, the old way required pulling the console for access.

Air&Road · #7 01-27-2013, 10:38 PM

Is there not a rebuild kit for that pump? What will destroy the engine is the roller coming loose.

jay_bob · #8 01-27-2013, 11:02 PM

From what vstech told me is that the vac pump bearings fall out of the open frame bearing assemblies, and the balls drop into the timing chain. This causes the destruction of the timing and valve train.

When we replaced my OM603 pump, John indicated there was no option but replacement with the updated design with safe bearings.

compress ignite · #9 01-28-2013, 02:59 AM

REPLACE THE VACUUM PUMP BEFORE THAT 603 TURNS ANOTHER REVOLUTION !

The Mechanical V.P. s ,New and Old Style are SAFELY to be changed out every
100,000 Miles.All else is RISK !

You have some Vacuum ("Motors") Actuators that are BAD also.Under the Dash.

compress ignite · #10 01-28-2013, 03:08 AM

On ALL Mercedes are JUNK as far as Longevity.
It's almost as if Mercedes TOLD Pierburg to manufacture them out of Crappy
Cast Junk Metal!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

_________________________________________________________________

It Really tells me How Far from Reality Montvale and it's Parent Company
Mercedes are to see Television adds claiming:

"The Best or Nothing"

THAT CHASSIS and the Craftsmen who built it RUSTED AWAY A GENERATION
AGO !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

MORE Like, HOW much Madison AVENUE Cat Poop will Americans accept in Lieu of QUALITY????

Harrison W · #11 01-30-2013, 12:53 PM

Quote:

Originally Posted by compress ignite

REPLACE THE VACUUM PUMP BEFORE THAT 603 TURNS ANOTHER REVOLUTION !

The Mechanical V.P. s ,New and Old Style are SAFELY to be changed out every
100,000 Miles.All else is RISK !

You have some Vacuum ("Motors") Actuators that are BAD also.Under the Dash.

Well, it's pretty cold up here in my neck of the woods. I have to drive the car to a friend's garage to work on it. So, keep your fingers crossed! I hope the pump doesn't decide to fail on the way there. I have the pump ordered.

Vacuum motors? How do I access them? And how do I fix them, or replace them?

jay_bob · #12 01-30-2013, 07:02 PM

Your best bet is to go to startekinfo and pull down the FSM chapters you need.

First get the vacuum pump replacement procedure and change that pump.

Then get the climate control test procedure and see what you really need to do to fix the ACC. The vacuum motors are called actuator pods and require removal of the dashboard to access. That is a difficult job, no need to do that unless necessary.

The ACC goes into safe mode if something in the controls fails, max heat and max defrost. Everything defaults to this state if is not working.

Harrison W · #13 01-31-2013, 01:47 PM

Quote:

Originally Posted by jay_bob

Your best bet is to go to startekinfo and pull down the FSM chapters you need.

First get the vacuum pump replacement procedure and change that pump.

Then get the climate control test procedure and see what you really need to do to fix the ACC. The vacuum motors are called actuator pods and require removal of the dashboard to access. That is a difficult job, no need to do that unless necessary.

The ACC goes into safe mode if something in the controls fails, max heat and max defrost. Everything defaults to this state if is not working.

Alright, I'll get on that after the pump gets put in. It arrived here yesterday. After reading around this forum for Vacuum pump related things, I'm pretty surprised and lucky that the pump on my car has lasted this long. And to think I've driven it on long road trips, not knowing about the problems old VP's can cause. :\

I'll be putting it in today. I've been looking around the internet, and I can't seem to find any sort of instructions, pictures, or anything of that sort about the replacement procedures. Other than the little instruction pamphlet that comes with it.

BobK · #14 01-31-2013, 02:26 PM

Not a hard job at all. Stop by the 25cent car wash and hose off the front of the motor to make the job easier. Loosen the belt tensioner so you can move it back and forth out of your way as you work Take the big vacuum line off the pump. Be careful as an old line is brittle. A bit of PB Blaster down on the nut, between the nut and the metal pipe helps. If it makes it easier for you, take the bolts for the fuel filter assembly out and push it back out of the way.

Clean out the allen head cap screws real well and be sure the allen bit is driven all the way into the cap screw. Crank them loose like you mean it and they will come out. Try to loosen all of them somewhat before taking them out all the way; just slowly keep working your way around the pump. The pump will eventually fall out and oil will run down the front of the motor. Have rags ready.

Clean up the gasket surface on the block real well so you avoid any leaks. Oil seems to love to leak at the bottom of the pump to block gasket and then the belts and pulleys throw it all over the place. (Wonder how I know!)

Like mentioned above, easier to put back together if you crank the engine around so that the wheel in the pump matches up with a valley in the ramp on the timing device (that's the sprocket the chain is going around). It still will not sit flush whne you first hold it against engine but at least you will be able to start the screws. Tighten them slowly so as to keep the pump moving in fairly flat to the block. Torque to spec and put the rest back together.

I was having some issues with the injection pump on a 601 (4 cylinder version of that motor) and you have to remove the VP to remove the injection pump. I could probably do it in my sleep now since I pulled it so many times.

Harrison W · #15 02-02-2013, 09:11 PM

I've run into a little problem. The pump is out (it looks like it got replaced in 96' per the date on the pump, and no open bearings) and I have two gaskets. One came with the pump (Pierburg) and one I bought separately. The gasket that came with the pump has a 'dam' on it, and the separate doesn't. Do I use both, the dam gasket, or the regular gasket?