Good afternoon

Looks like you got an issue with that booster, if you are direct from the vac pump, and it's drawing a vacuum.

The only thing that happens when you compress the brake caliper pistons is that it sends the excess brake fluid back up into the brake fluid reservoir, nothing else! But I wonder, did the reservoir overflow when you compressed the calipers? Is it possible that BHD's experience with fluid going where it's not supposed to go making hard braking? I don't know the answer to that, but it does seem odd that the booster would just die at the very same time you serviced your wheel bearings!

your direct setup
 

of the hose to the booster is not per factory. the fact setup has a check valve in it. so maybe that is the problem.

tom w

the hose in the pic is not factory... as I posted I made it up for a test only situation..left the tee out on purpose for test.

anyway.. put on the new booster today and all is well!

who knew and why it happened is beyond me. The only thing different would be in the future is that I will bleed down the caliper while I am seperating it so that nothing is reverse pressure on the booster or master cyl.

might help someone else and save them the grief I went through.
BTW you can do the booster in about an hour and do not need to remove the master cylinder to do it.

bennett

glad you got it
 

still trying to imagine how you installed the brake booster wo removing the mc.

also still dont beleive what you did with the caliper had anything to do with the problem.

tom w

Just undid the nuts on the front of the MC and took the clutch res supply line off and plugged them both. Moved the master toward the front and down toward motor. It took a little time but was actually pretty easy. The hardest part is removing the upper left nut on the booster under the dash. Blackhawk angle head geared 13mm wrench fits the bill. We were not about to go through clutch bleed hell so we did it this way. :D Wouldn't do it any other way.
As far as the caliper causing the problem.. I don't believe in coincedence
either but .... soemthing cause that booster to go bad at the same time.

one more thing that might help others ...

we ran a small vac tube from the tee in the oem main vac line and ran the tube into the car hooked upm to a vac gauge... started the car and drove around the block , vac showed 20 hg ... As soon as you touched the pedal the vac would drop to zero...seemed reasonable that the booster had to be the problem. Engine IP shutoff works great now. I wondered how many guys out there suffer similar confusion when there car won't shut off???... the vac all gets robbed by the faulty booster. The engine not shutting off was the first symptom of problems after we did the bearings too... glad this headache is over. Hope it helps someone else.

bennett