vacuum pump rebuild ?

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jethrobodean
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vacuum pump rebuild ?

Postby jethrobodean » Mon Sep 07, 2009 4:32 pm

I found the problem with my heater and the control of air from top to floors. Its the vacuum pump not producing enough vacuum. I put my mighty vac on the line going into the car and found that 6lbs of pressure is needed to switch from top and bottom and my pump is only producing 4lbs. There is no leaks in the system under the dash. How much vacuum should be produced?
82 VW rabbit diesel Ls 1.6NA

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Postby Quantum-man » Mon Sep 07, 2009 5:01 pm

THe vac pump produces no pressure, it's a vacuum pump remember :?

It should produce 25 or more inches mercury or is it water :wink:

If it's a vane pump:
http://img78.imageshack.us/img78/4862/v ... eupwb3.jpg

then, its crucial oil level is maintained to drive vanes out, [it's not centrifugal :!: ] but if vanes get chipped they can be turned to give new scraping edge...
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Re: vacuum pump rebuild ?

Postby Quantum TD » Mon Sep 07, 2009 5:29 pm

jethrobodean wrote:I found the problem with my heater and the control of air from top to floors. Its the vacuum pump not producing enough vacuum. I put my mighty vac on the line going into the car and found that 6lbs of pressure is needed to switch from top and bottom and my pump is only producing 4lbs. There is no leaks in the system under the dash. How much vacuum should be produced?


Bentley manual has procedure for rebuilding the rotary-style pumps. It's in the BRAKE section of the manual.

For a temp fix, you might try to install a vacuum check valve inline to the cabin. It may help a bit.

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Postby 82vdub » Mon Sep 07, 2009 5:52 pm

If it's the diaphragm style pump, then these are rebuildable really easy. Just to be sure it's the pump itself, do a vacuum test on the pump, with no lines connected (other than the tester) and all ports blocked. If it's much less than 15 pounds (or higher), then rebuild it.
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jethrobodean
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Postby jethrobodean » Mon Sep 07, 2009 6:33 pm

82 VW rabbit diesel Ls 1.6NA

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Postby Quantum TD » Tue Sep 08, 2009 12:20 am

Get a Meyle kit. It includes all you need.

There's the main diaphragm and then the one for the cap (top) of the unit. You will need to take the top off to rebuild the pump, so that's why they include it in the kit.

Then there's the rubber o-ring, and a new lock-nut.

A new kit should run like $10

Try Jack. He may have them.

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Postby 82vdub » Tue Sep 08, 2009 8:42 am

I replaced the diaphragm style pump in my 82 Rabbit two years ago. It had 240K miles on it. I've never replaced more than the rubber diaphragm that goes between the two halves, which is what was pictured in the ebay auction. I've never disassembled the check valves or anything else. Just changed the diaphragm in 240K miles. I would say to leave the check valves as they are unless they need service.
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Postby Fatmobile » Wed Sep 09, 2009 12:22 am

Be sure to look at how th eoil pump and vacuum pump are getting along.
The 2 can wear on each other.
Pushing the oil pump down and the vacuum pump upward against the brass bushing.
They can eventually release each other completely;
the oil pump screams and stops spinning.
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