Molly

Hi, my brakes in my 86 951 seemed to be weak / non-assisted, and you would almost have to break the pedal to do a hard stop. So to debug it I placed my mityvac on the brake booster line at the T and held no vac. So took off the last hose to booster, including the check valve and it holds vac fine (by pressing my finger in one end and mityvac on the other.) Thinking then that the booster may be shot, I pressed a vacuum cup over the booster hole (since the check valce and hose were out) and it will not hold any vac at all.

So a) shouldn't the booster hold vacuum at that hole and b) can the booster fail inside in a way that it does not hold vac at all?

Just wondered before I tear the whole booster out.

Thanks

V2Rocket

there's a huge rubber diaphragm inside to separate air from vacuum...it will rip eventually after so many cycles of use.

Molly

Yes thanks... I know that... but I was wondering if it would be normal for it to hold vacuum in my test or not. Thought maybe there was some mechanism that might cause it only to work properly when running or if there was any other type of valve controlling it. But I guess since it is not holding vacuum, it should head out to pasture. Thanks!