Brakes needing to be pumped after new master cylinder

[brewvan]

Hey I have an 86 vanagon and I put a new MC in, changed 90% of the hydraulic brake lines, but GW stainless steel hoses on, and bleed the system multiple times and I have to pump it two or three times for it to firm up. Any ideas? Also side note but I noticed the little rubber seal for the cap has a crack in it. not sure if that has anything to do with this.

[Glenn]

Did you bench bleed the master before installing?


Link

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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
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[brewvan]

I did bench bleed it

[Altoona]

Did you replace the wheel cylinders with ones missing the internal springs?

[brewvan]

If I pump it up it holds pressure great until I let my foot off.

[Altoona]

[brewvan]

Wheel cylinders haven’t been touched

[Ahwahnee]

[syncrodoka]

[brewvan]

I’ll try pressure bleeding. Is it possible for that to happen if my drums are not adjusted equally?

[syncrodoka]

Properly adjusted rear brakes will give a correct, higher brake pedal. I always adjust them first but your system needs to be bled.

[Ahwahnee]

The arrangement I use to apply modest air pressure to the system for thorough bleeding.

https://www.thesamba.com/vw/forum/viewtopic.php?p=9386081&highlight=tube#9386081

[?Waldo?]

Rear brakes significantly out of adjustment will require pumping for a solid pedal, e.g. first pump moves the shoes close to the drums, next pump gives the solid feel.

[Wildthings]

Did you do anything at all to the rear brakes? If so, what?

[brewvan]

Ahhh gotcha. I haven't done anything to the rear brakes because ive been unable to get the drums off. it does seem that the passenger side rear isn't adjust the same as the other side. any advice on removing the drums?

[Wildthings]

[raygreenwood]

[brewvan]

Here’s some info and an update. Removed the drums and cleaned the everything up. Installed new German built wheel cylinders. Re bench bleed the MC. Re bleed the whole system in the correct order multiple times. All the fittings are tight and leak free. No air is coming out even with a pressure bleeder. The MC I bought was from go westy and it’s the classic line brand. The brake pedal holds fine when the engine is off and I pump it up but when the engine is on the pedal slams to the floor. If I pump up the pedal while it’s running the brake pedal falls slowly to the floor. Any thoughts?

[MarkWard]

Stock engine? Stock brake booster?

[Igeo]

I'm starting to think you got a bad master.
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