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No pressure to back drum brakes

I have a 03 gmc Sonoma that’s been sitting idle for at least 3 years…I was attempting to bleed brakes but cant get any fluid to back drum brakes…I opened the line at the back right where it splits to let and rt brake line…it was dry not a drop…the front bleed easily…i dont know if its thr combination valve or my abs system…any help is very much appreciated…thx

Bob, we don’t know either. Loosen the lines at the compo valve to see if you have fluid there. Then go to the ABS unit and crack one of those lines as well. Then come back and tell us what you found.

Are you mashing the brake pedal to push the fluid or just trying to let gravity move the fluid? If just opening the lines, it might help to have someone press the brake pedal to help force the fluid.

Check for pressure at the master cylinder. You don’t need to remove the lines. Just have someone pump up and hold pressure on the brake pedal while you quickly crack open each outlet to see if pressure is there. You can presume that if one has no pressure it’s to the rear brakes.

I have the bleeder screw open and attached to a 1/4 in tube inside a bottle half filled with brake fluid…then I push on brake pedal…but nuthin coming out…front brake calipers are bleeding well.

Will do…I’ll use some kind of bar from pedal to seat to hold pressure since I’m by myself on this.

If you have a hood prop rod

they work great. But I suggest you put a cushion at the seat.

I gotta 10’ piece of 3/4" ridgid pipe I’ll cut to fit…and yea a cushion for sure

Why not just use a brake/gas pedal hold-down tool?

I made mine out of an old caulking gun.

Tester

4 Likes

Now that’s good ol American ingenuity…And I e got 1 around here somewhere…thx

Hey. Maybe that’s your million dollar invention…never know…simple but ingenious.

I use a branch from an old cherry tree. Close the front bleeders first, then work on finding the problem w/the back wheels by locating the point in the hydraulic system where you have fluid, then after that point you don’t, one side at a time. I’d guess it’s either the ABS or the MC.