have you tried the proportioning valve. sometimes dirt will get in there and clog the returns.
It's rare....because usually the master cylinder will allow pressure to bleed off. Not the other way around. But if you have replaced the calipers, this is the next thing I would check. I suppose it could be sticking.
I had one do this and I had to change the brake calipers. Problem was gone.
Air in system? Remove and bench bleed master cylinder Bleed lines and calipers
master cylinder is sticking
seized calipers?
the pistons inside your calipers are sticking
Check for sticking calipers.
The brake proportioning valve may be sticking, but this is very uncommon. Did you lubricate the slider pins on the caliber or replace them if they are rusted or corroded? Check all contact points and clean them off throughly. Apply brake lube to all contact points.
old break hose collapsing and or pistions sticking in calipers.
usually either the calipers have dirt in them and need to be replaced or the rubber lines leading to them have collapsed inside and need to be replaced.. really kills the gas mileage uh!! chevy has had problems with rear discs on these vehicles,70%of braking is on the front,30% on the rear. therefore the pistons get little use and stick. there are stainless sliders the calipers move on,you need to clean and lubricate them,this should stop the brakes from dragging. I have a 1999 Blazer and my rear brakes were grinding so I replaced the pads and rotors but had the same sticking problem. They dont offer a rebuild kit for my calipers so I had to replace the calipers also.
Hi. If the brakes are sticking on it won't be the servo thats at fault it's sound more like the calipers need cleaning.
you probably wont be able to move? or you can take it around the block, then when you get back dump some water on the calipers.. if it sizzles then there is a good chance they are sticking :)