Thread: Hmm

Yep

Check to make sure you dont have a leak at the caliper piston. Sometimes they can develop a seal leak when the piston is pushed back into the caliper. The leak may be small enough to allow for a firm pedal with the engine off but will push fluid past the seal once you apply vacuum to the booster and increasing the mechanical advantage of the brakes

Thats the dust boot and really doesnt do much more than keep moisture and dirt from getting in to where the actual seal is. If it is torn, chances are there may be some dirt in behind it. Moisture can cause corrosion on the piston. Mix that with some dirt and its not hard to see how the seal can get damaged.

get some de greaser and clean up the booster, and then spray it with some brake cleaner. so get it clean, and see if a fluid trail starts up again, if its getting wet at all, the master cylinder is leaking.

if you pump the brakes does the pedal firm up?

and 100% of the time if you have fluid and dirt and gunk under the master, where it bolts to the booster the master is leaking, its the only thing with fluid there, and thats where they leak from.

true that^^^^^^^^

If the pedal goes slowly to the floor your master cylinder could be worn out and letting fluid back into the master cylinder.

but even if the cars off, if the master was bad the pedal would sink to the floor when pushed.

the boosters not to hard to change, take the master off, 2 nuts, usually 4 bolts holding it to the fire wall, and a rod that clips to the brake pedal. and the vac hose.

check your vac hose out as well for cracks.

ive seen masters go bad with out leaking before. that being said, the pedal would still hit the floor with the car off, aka no vacuum.

the booster is just power assist really. the rod on the brake pedal pushed another rod through the booster and pushes the piston inside the master. the master knows not if it has a working booster or not.

oh and you live in the rust belt, so if you had a rust spot on the booster it could leak air. if its rusted enough.

yes im thinking booster, and its not cheap at all.

id be looking at a junk yard. to be honest they very rarely go bad.

ive done 2 in my life, both in pick up trucks, one was a hydro boost, same deal, just add some fat lines to it now that lead back to the power steering pump.

have tried bleeding all the calipers and the abs yet? if your pads went real low and so did the fluid, you could have sucked some air in the system.

even a system with air in the lines will pump up and hold pressure when the cars off. running it may just have the power to push the pedal down further due to air in the lines.

did you bench bleed the new master, because that one is supposed to bleed on the car, its attached to the abs pump right?

if so, if your standing at the bumper looking at the master and abs there, facing you on the abs pump is 2 bleeders bleed them both just like a caliper.


see the 2 nipples? you may be a bit different but they all bleed the same.

we're talking about a 98 right?