GMC Brake problems. Light won't stay out, Pedal spongie

Anyone know what I missed to do? Had to replace the rear brake caliper (siezed) on my 96 GMC C2500 HD pickup. Bled the line and the brake is working fine. But I can't get hardly any pedal. Even when you pump it you can make the brake light go out. But it comes right back on when you hit the brake. And there still is hardly any pedal. Do I need to rebleed all four brakes?

Reply to
Daveman
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Yes, always. and especially if you let the master go dry while you were changing the caliper.

Whitelightning

Reply to
Whitelightning

How are those brake lines? May be time to replace those as well.

Reply to
Sigwings

Doesnt your emergency brake still work? Use it instead.

Reply to
Bryan Collier

Yep, Air in the line. If you only bled the line you replaced WHY?

Reply to
Steve W.

Do you mean that the brake lights stay on even without applying the brakes? If so, after following the advice else-thread about bleeding should the light issue remain you can adjust the brake-light-acuator via a plunger switch, usually located near the top of the brake pedal arm. If you're seeing too much free play due to wear a vacuum cap can serve to lengthen the plunger. This will do nothing (good) for you in the case of a weak pedal, due perhaps to having air in your lines: Do check and follow the other advice.

Reply to
Don Quixote

I was hoping I didn't have to bleed the whole system. Resivoir didn't go dry. and all the lines were replaced when I put the disc brakes on the back last year. Didn't want to go through the fix a line one day and fix the next line the next day. (Seems the way brake systems always go for me.) I guess from the replies that the next step is to just bleed them all. One of these days I'm going to have to get one of those pressure bleeder. Wifes leg tires out too fast! Thanks everyone.

Reply to
Daveman

Vacuum bleeder? I got one. They are not expensive. The reservoir doesn't hold enough though.

Reply to
Bob La Londe

if the res. didn't go empty i would try re bleeding the two back ones first. do your back wheels grab at all? you some times get air in the master cylinder or ABS motor.

Reply to
taz

Yes they "rub". I'm thinking the equalizer valve is not balanced anymore. I've got full braking in the front and a good rub in the back. Then the light goes on. Tap the pedal twice and the light is back out.

Reply to
Daveman

The valve is never balanced. First off a combination valve holds off the front untill the rears start to apply. The reason for this is the rear wheel cylinders have to over come the return springs. You still have air in the system.

Whitelightning

Reply to
Whitelightning

try this, I think it could be your problem. I've seen it happen on some fords but...

if you can get the rear brakes to bleed out at all (i.e. little pressure, but you're getting fluid) then bleed it out as best you can, then turn your key to run (but don't start) and stomp the brake pedal. you may have to do it two or three times, but when you "flip" the prop valve, the pedal will feel different, and the brake light will go out...

if that doesn't work.... close the rear bleeders, have an assistant open one of the front bleeders, and hit the pedal hard... once again w/ the key in "run" and watching the brake light... once stomped, hold the pedal down until the assistant closes the bleeder... repeat if necessary....

once you get the valve flipped, bleed all 4 normally from farthest to nearest the master (RR, LR, RF, LF)

Reply to
ShoeSalesman

Hey ShoeSalesman, Gave the stomp idea a shot. So far so good. pedal still a bit spongier than normal. But my assistant, The wife, wasn't up to helping yesterday. So I'll bug her this weekend to try bleeding one more time. Found if I pump it three times every other morning before I leave for work. It seems fine. So I'm hoping that with a good bleedout now it will be done.

On a side note. I wound up taking the truck back to stock from the cam issue you helped me with over the winter. Thanks again for your help on that one! Even made money on the ZZ502 cam when I sold it on Ebay. So that worked out ok. (Made the wife feel better about what I spent to bring it back to life anyways!) Thanks Again!

Daveman

Reply to
Daveman

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