I have determined that my brake booster is leaking and should be replaced. Do I have to completely remove the master cylinder from the car or can I just unbolt it from the booster. I may just try replacing the seal first between the booster and master cylinder. This would save a lot of work.

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Mr Goodfahrt (pronounced FAIRT... means "good trip" in German)

1982 300D Turbo Pastel Gray (off-white) 200k+(?)
newbie but willing

Isn't this saying the same thing? If I were doing it I would just disconnect the brake lines, remove the booster/mc bolted up and then remove the mc from the booster after I got it out of the car. It is really six of one and half dozen of the other if you remove the mc and then the booster.

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Jim

No, I think the question is,
can you leave the brake lines all connected to the MC, unbolt it from the booster, sneak the booster out, and avoid all that brake bleeding?

the seal is housed in the MC.
you can just take the MC out but that little ring seal holds vacuum not fluid (the little ring in most catalogs)...when mine was weeping it was internal and into the booster, so i got a new MC. but i also replaced that little seal.

just some info
Jake

Yes... I did mean can I avoid disconnecting the MC lines. There are several of the metal lines and I am trying to keep it simeple. My goal is to try just replacing the seal first to see if that is causing the vacuum leak. If that fails, I'll replace the booster. The booster is not holding vacuum, but it may be that seal between the MC and booster.

Thanks...

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Mr Goodfahrt (pronounced FAIRT... means "good trip" in German)

1982 300D Turbo Pastel Gray (off-white) 200k+(?)
newbie but willing

How do you hook a vacuum pump to the booster to test. I still have a pump that I loaned from Autozone. It only has the regualr size vacuum hose on it.
Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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I did it 2 ways. 1st was process of elimination. I removed the hose connecting to the booster, plugged off the 2 hoses going to the engine and locks/climate control etc, and determined my vacuum pump was ok (blocked booster end with thumb). Then, replaced hose to booster and checked from one of the hose 2 fittings while leaving the other blocked (golf tees work great). Final test was to use a cone shaped universal adapter that came with the Mity-vac that I had to hold against the booster fitting. Both tests confirmed a leak at the booster. This took a lot of pumping. Leak may be just the seal between the booster and master cylinder but is probably booster.

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Mr Goodfahrt (pronounced FAIRT... means "good trip" in German)

1982 300D Turbo Pastel Gray (off-white) 200k+(?)
newbie but willing

actually I am facing the same problem as the person starting this post....namely, can the booster be slid out while the master cylinder is left bolted to the brake lines....

If I remember correctly, I think I DID do exactly that on my 260K+ 84 300SD car when I replaced the booster, I believe there was enough clearance to do it that way....I'm not if its advisable as I was worried about bending the brake lines back and forth during the removal process. On that car I had replaced the MC first and then had decided months later to replace booster. That was over 5 years ago now! ... Maybe someone else can comment.

my symptoms on the 160K car are of : hard brake pedal on cold starts that returns to normal after revving briefly. Only happens on cold starts, indicating a tiny leak....clearly a sign of vaccuum loss. I feel confident that it's not the vaccuum pump since all other vaccuum systems (namely tranny shift, etc working ok) and I had the dealer do the vaccuum pump a year ago (expensive!)

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1) 84 300SD 285K+ Miles (Ver Calif)
2) 84 300SD 175K+ Miles (Ver Federal)

No problem replacing the booster without removing the MC entirely. There's room.

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Ash Peltier - tools, truck, tales
---------510-331-4118-----------
1982 240D - (272,000)
1998 Honda VTR1000F(RT) Superhawk Freeway (58,000) "Madrid"
1996 Toyota T100 4x4 (84,000) "Mary Kay"