I'm an old guy from the days before ubiquitous power brakes. When I was young a brake peddle that slowly collapses to the floor with steady foot pressure was a sure sign of a failing/failed master cylinder (fluid leaking past the seals). My '94 Camry began doing this yesterday. When I said to a friend "I guess I need a new master cylinder," he said, "It's probably the brake booster." I guess that's possible, so . . .
Could it be either of these?
If so, how can I isolate which of the two it is?
Does your car have a vacuum booster (big metal can behind the master cylinder)?
It's likely the master cylinder. The firewall-mounted booster is a push-through affair that has a little bit of slop between the pedal rod and the master cylinder. The slop is to allow a valve to shut off the vacuum supply to the backside of the booster's diaphragm and to let air into that side so that the vacuum on the forward side sucks the diaphragm and pushrod forward to apply the brakes. A shot booster will give hard pedal, not much else. Now, if the master cylinder is leaking fluid past the aft piston seal, that fluid could be getting into the booster and wrecking the diaphragm. Is your master cylinder losing fluid?
Dan
It is possible it may be neither. Have you looked under the car? Fluid could be leaking just about anywhere in system. If there is no sign that fluid is disappearring anywhere then it is probably the master cylinder.
-jim
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Are you going through a divorce? :-/
Yes, it is very likely that you have a failing master cylinder.
How much does a new or rebuilt master cylinder for that car cost? I don't know why I ask.Could be you have a leaky brake cylinder. cuhulin
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