How do I get brake pedal pressure
Asked by Katmandude Jul 01, 2018 at 01:27 AM about the 2007 GMC Envoy SLE-1 4 Dr SUV 4WD
Question type: Maintenance & Repair
I removed left front brake caliper on "07 GMC Envoy because it seized up. the new caliper was wrong part so I ordered new one..Overnight, with the brake line to the caliper disconnected brake fluid drained out of the reservoir onto the ground. Once I reinstalled new caliper and topped off reservoir, I can not get a hard pedal by bleeding, I get good flow out of bleed plug but pedal keeps going to the floor, will not pump up and no pressure is applied to rotor, can turn it by hand.What is wrong, I have never had this issue bleeding brake fluid from "other vehicles", the pedal would always pump up after bleeding the calipers?
10 Answers
You will have to Bbleed starting at the MC if air got into the system. Bleed the MC, then the closest wheel, then the other front one then the closest rear wheel to the MC, then the remaining wheel. Brake fluid could be contaminated now to and bleeding all of it will probably solve that too if you do it right. You don't need two people either, you just need a hose that fits tight on bleeder, a large jar full of new fluid, submerge hose to bottom of jar, and use a small board that you can pin between brake pedal and drivers seat and this works with manual or power seats to keep the pedal depressed as you tighten the bleeder. just keep close eye on the jar of fluid so you don't suck up more air.
BritishTech77 answered 6 years ago
C is right! You have to start from scratch! You must first bleed from the furtherest wheel and work your way to the closest. Go and buy a 1 man bleed set (It contains and 1 way valve like $6) or like he said use a transparent hose with a bottle of brake fluid to bleed and just keep filling up reservoir until its completed!
Katmandude answered 6 years ago
OK I ordered up the bleeder kit, always wanted one anyway! One concern that I have is I have read that I may need a scan tool to cycle the ABS pressure modulator if there is air in it there is no other way to remove it. IS this true?
BritishTech77 answered 6 years ago
To bleed the isolation valves in the modulator, there are two bleeder screws. Start with the one toward the engine. Turn the ignition on and apply light pressure on the brake pedal. Open the bleeder screw and allow the fluid to flow until clear.
Katmandude, you'll never get good pressure unless you have a high end scanner like a Tech II that can open the ABS module, then you can bleed properly. I'm going through the same thing on my Trailblazer. You can try 1 method, remove the ABS fuse, drive around for a while. Then power bleed it. I like using the Motive power bleeder, pressurizes the MC while keeping it full of fluid at the same time. The 2nd method doesn't always work. Best to have a pro that has a scanner that can open the ABS module to bleed properly.
We blood all the wheels and the master cylinder and we still get no pedal
Blade all four wheels and a master cylinder still get no pedal
I know this is an old post but I thought I'd share and hopefully help someone out in the future. I replaced a caliper on my vehicle and couldn't get no pedal after bleeding. after much frustration and an expensive trip the mechanic, it was found that the auto parts store gave me the caliper for the wrong side of the vehicle. it actually mounted up fine and I was pressed for time so I didn't notice anything out of the ordinary. with the caliper on the wrong side it put the bleeder screw at the bottom of the caliper so there was no way all of the air could be bled out. just make sure bleeder screw is on top. hope this helps someone...
03 GMC envoy sle. Notices there are to bleed valves on the back calibers bled back passager side first,no issue on back driver side noticed only one bleed valve and a Alan wrench smaller opening where the 2nd valve was on the other caliber. No fluid leaking from opening. Bled the top valve and moved on. Still no pressure when I start car. Even though before starting car brake pedal had pressure built up. Reservoir full any advice ?