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Old 03-27-2003, 07:13 PM
erubin erubin is offline
Registered User
Join Date: Mar 2003
Location: Los Angeles, CA
Posts: 445
Brake booster and vacuum pump

Sadly for me no one stepped in to give me any advise. Here is some follow up info and questions. I was unsuccessful rebuilding the vacuum pump as it was unable to pull a vacuum after reinstalling. Maybe i scored the center hole of the pison where the threaded rod comes through. It suprises me that the center hole is sealed with a metal (steel or was it aluminum?) washer topped with a nut, how air tight can that be? Instead I ended up paying $204 for a new one and I'm now getting 23" Hg instead of the 17" when i first tested the old pump isolated form the rest of the vacuum system.

My brake booster is also a problem as it is unable to hold any vacuum. I picked up a booster for $75 at a local MB salvage yard today. It tested OK in the yard with my Mityvac --no noticeable leak after 15 minutes of waiting. I had no idea if these things can be rebuilt and I can't afford to disable the car during the day as it is one of our daily drivers so I went for a used one.

Does anyone know if the o-ring between the master cylinder and the booster should be replaced? Also how should the inside of the booster be cleaned without damaging the diaphram. There is no obvious fluid but appears to have a light film of oil in there. I saw the salvage guy struggling under the dask to remove it and he simply cut the break lines to move the master cylinder out of the way. I guess i'll have to disconnect the brake lines to the master cyl to replace the booster? Any tricks to make this job easier/quicker?

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