Both new calipers and pads,,new master cylinder,,bench bledbefore installed,,no leaks on both rear wheel cylinders,,brake booster test,,,ok! Seems ok when manual bled and air bled engine off,,did bled same sequence but pedal goes to floor when engine run,,would say,,,,no brakes at all, abs pump problem? Pls need some input,,,$500 est at least down for parts ,,still no brakes at all?
For the pedal to go to the floor there is still air in the brake system. Start again starting from the longest line bleeding each in turn to the shortest line . make sure you have adjusted up the rear brakes before bleeding as every time you press on the pedal the shoes expand right out and when you take your foot off the pedal the shoes go all the way back in. adjust them manually and do not rely on the self adjuster as it only adjusts on wheel movement
it sounds like your still not getting all the air out of your lines. it helps to have a brake bleeder but they are expensive, it also could be that the gasket inside the master cylinder is inverted even if it is a new master cylinder this could be the case, ive had four bad remanned ones in a row, before i got a good one... hope i could help
You need to check wheel cylinders, the only way that the brake peddle will go to the floor like that is if there is a lose of fluid pressure somewhere .
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Have you checked the master brake cylinder reservoir for brake fluid loss?
I don't suspect the master cylinder as you have replaced it... but am more suspect of a leaking brake line or fitting which should have
been discovered when you had the system bled.
The only time I ever had a rear brake problem with a 2500 series Chevrolet was due to seized rear brake caliper guide pins...as your calipers are also new that is not your problem.
If your brake pedal feels spongy and travels to the floor board you have air in the system, a brake fluid leak or a failure in the power steering system, such as a broken hose, broken power steering pump drive belt, or failed pump, would result in a loss of pressure to both the hydro-boost and steering.
You probably need to start over...1st by bench bleeding the master cylinder...(you can do this on your truck...review the bleeding instructions...after completing this you need to be sure the master cylinder is full of brake fluid...you will need a helper...but your next step will be to bleed each wheel brake caliper or cylinder. Start with the right rear, next left rear, then right front to drivers side front...(farthest away to start) you may have a brake fluid leak...if not, your pedal pressure should continually raise...Hope this helps.
Did the pedal go to the floor beforehand? Was the master cylinder leaking, and did you bleed it properly? If the master cylinder was not leaking, check your brake lines going to the rear wheels.
The liquids does not compress, so there is no reason for the brake pedal to go to the floor. If you have no brake pressure, after bleeding the system, then the master cylinder is wasted. The brake master cylinder leak might be Internal, or External. Check around the master cylinder for any external leak. The break fluid is an excellent paint eater, so clean any leak before you remove the Master Cylinder. The new Master Cylinder needs a bench bleeding process, before installed in your car.
no they are inverted flare fittings no seals check all lines and calipers/wheel cylinders if all are dry remove the vacuum hose from the booster if there is brake fluid in the hose the master cylinder is bad
Did you bench bleed the master cyl. before installing it? then when you installed the new master, did you bleed all 4 points? If yes, then check all for points for leaking caliper/s and leaking wheel cylinder/s. If the van has ABS, check the valve body for a bleeder screw and see if air bleeds out of it. If you've checked everything twice and did everything right then your new master cyl. may be defective.
10
Inspect
Master Cylinder (Brake System)
Worn or leaking brake master cylinder.
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