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-   -   123 Vacuum Pump rebuild (http://www.peachparts.com/shopforum/diesel-discussion/209425-123-vacuum-pump-rebuild.html)

joshhol 12-30-2007 12:24 PM

123 Vacuum Pump rebuild
 
I'd appreciate some feedback on the direction to take with this vac pump rebuild.
My brother's 1985 300D was only making about 5 Hg vac and not shutting off, no power assist brakes etc.

I pulled the pump, sure enough one of the check valves was cracked.
I installed the parts from the rebuild kit and I think I did it right but put back the pump and still no suction. Pulled the pump back off, checked installation of the check valves. The main check valve at the hose inlet was tested by blowing and sucking. It passed that test by not allowing suction but I was able to blow air through it in the direction of vacuum.

I don't see what could cause it not to produce vacuum. Is it possible that the rings that go around the piston were pinched or compromised on installation?

In perusing the threads, I see that an argument can be made for just putting on a new pump because of the possible devastation caused by the pump arm bearings.
I'm leaning towards that as the car has 275K.

But, I'm just curious as to what would cause my rebuild job to fail.

Thanks

tangofox007 12-30-2007 12:31 PM

The valve seals supplied in some overhaul kits are too thin. If that was the case with yours, the check valves won't function properly.

Craig 12-30-2007 01:06 PM

After paying about $2500 for the engine damage resulting from a vacuum pump failure, I replace the entire pump the first time it looks like its considering thinking about maybe failing. I just replaced one after about 60K miles due to a slight click that could be heard with a stethoscope.

joshhol 12-31-2007 03:50 PM

Tangofox you nailed it.
The new seals were 1mm thick, the old 2.5mm. Quite a difference. Fortunately the old seals were still soft and pliable so I reused them which solved the problem.

I couldn't see anything to my untrained eye that would cause me to think the bearing was going to fail. I've heard they give fair warning so for now, it's going to be the old pump.

I guess moral of the story is don't throw away anything until the job is done and carefully compare ALL parts from new to old. This is the second kit (first one was power steering pump) with wrong sized seals. Fortunately my mechanic knew about the ps seals which undoubtedly saved me hours of pain.

cbender 07-31-2008 04:36 PM

So now that I have read this thread and already have rebuilt the pump with no luck. Where might one get the right size o rings if I not longer have them?

Stevo 07-31-2008 05:59 PM

Damn, I did a rebuild and it didn't work so I pulled it off and threw on a used one I had. I should dig out my rebuilt one and check the O ring.:rolleyes: Thanks Tango

Diesel911 07-31-2008 06:41 PM

Quote:

Originally Posted by joshhol (Post 1718495)

In perusing the threads, I see that an argument can be made for just putting on a new pump because of the possible devastation caused by the pump arm bearings.
I'm leaning towards that as the car has 275K.

But, I'm just curious as to what would cause my rebuild job to fail.

Thanks

They sell an other kit that completely replaces everything on the on the drive side of the vacuum pump; are, pins, bearing and ect. The catch is that if you buy both rebuild kits it will cost almost as much as a new vacuum pump and the new pupm would come with a warranty.
Here is an example of a place that sells the Arm assembly. But some places sell the Arm kit for close to $300.
http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2FE00V9U72FH147MEK&yearid=1984%40%401984&ma keid=MB%40%40MB%40%40X&modelid=300%2DDT%2D001%40%40300D++Turbo&keyword=vacuum&mode=PA&subcatid=D3010 @@Vacuum+Pump+Repair+Kit


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