Got a 1991 Deville with around 48,000 miles on it. Pulled it out of winter storage and the brake pedal is spongy.. never was before.
The car has rear drum brakes, and to me it feels like other cars when a rear wheel cylinder pops. I havent been able to get the rear wheels pulled off to pop off the drums yet, but I dont see any fluid leaks, master is full and I dont have a brake warning light on.
With all due respect, I kinda gathered that. Was just looking for input on whether these problems were common or if I gotta find the time and dig in myself. No big deal either way.
No sir, it's not common. The pedal should not get spongy after being stored for the winter. It should be just like when you put it away. You'll have to dig in.
It may just feel spongier than the car you are used to driving. I have noticed different cars can have a very different feel in the brake pedal. Brake fluid is supposed to be flushed every couple years but nobody ever does it. Maybe yours is just too contaminated with moisture and really needs to be changed.
Seized self adjusters for the rear drums will give you a "low", soft pedal...else I'm really not sure what to suggest based on the limited info. Losing fluid at all?
there is a big difference between a "spongy" pedal -
and excessive pedal travel -
like Ranger said - the ONLY thing that causes a spongy pedal -
is air in the system -
IF the rear wheel cylinder has a slight leak -
you COULD loose a very small amount of fluid every time you press the brake pedal -
and suck in a very small amount of air every time you release the brake pedal -
and over time - you end up with enough air in the system to get a spongy pedal -
excessive pedal travel is most commonly caused by -
rear brakes that are out of adjustment -
dirty - non functioning rear brake self-adjustors -
the rear self-adjustors - on a drum brake setup -
will ratchet up one click - every time you apply the brakes while backing up -
providing they are working properly -
the other possibility is a master cylinder with an internal leak -
try this -
with the engine running - in PARK -
pump the brake pedal 10 times - then hold the pedal -
the pedal should remain hard - and at the same level -
it should NOT slowly sink -
i have found on some longer term storage cars that rust can build to a point on the rotors that it feels like there is air in the brakes.
this gave me quite a problem a while back so I would suggest having the rotors turned if there is eny rust on them in the area the pads make contact
besides that listen to basscatt
Finally got some time to mess with the car this afternoon. Pulled the drums off and everything looks pretty good. Bled the driver side rear and got a few burps of air but very solid fluid afterward. Bled the passenger side rear and got good fluid, some air, then no fluid. Bleeder is clean. Had him put a ton of pressure on the brake pedal then I loosened the bleeder, no change in pedal. Thinking it could be the rubber line back there. Any experience I've had with them being bad in the past they acted like a check valve the other way, but we'll see I guess. Hosed the rubber/metal line connection with PB today and tomorrow I'll try splitting it and see if I can get fluid from upstream of the rubber.
Didn't have fluid behind the rubber line this afternoon.
The line from the passenger rear side crosses over the car to the driver side and goes into some kind of filter looking thing. Both rear wheels run through one of the filter looking things? Does any one know what those are?
I sprayed PB on the lines around that "thing" and plan to check for fluid in front of it in a day or so.
I can take a picture later today if need be, but its not the master cylinder. These are a couple feet in front of the rear wheel along the "framerail". I don't believe it to have anything to do with proportioning because its so far downstream already and the left/right rear lines are separate. They run along and each separate rear line runs through one of these things that look like filters. There are no electronics going to them either.
Called a GM dealership and they actually are proportioning valves. Just for reference in the future I'll snap a picture of them and post it here.
Now to determine if I have fluid in front of it or not. That should tell me if its a faulty master cylinder or the proportioning valve. Still seems odd that one side has good strong fluid and the other side has nothing.
Wanted to update this because those open ended topics bug me.
Took apart the proportioning valve on the side in question and cleaned a bunch of crud out of it. Buttoned it back up, bled the brakes good and all is well again. Guessing the buildup is from sitting so many years. Thanks for the help and suggestions.
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