I have a 98 s10 pickup 4.3 4wd 5 speed. It has ABS and 4 wheel disk brakes. I had a brake line bust going to the rear. The proportioning valve did its job and I got home. I left it sit a couple of weeks and all the fluid leaked out. Now that the line is fixed I had to pump fluid in the bleed valves with a new oil pump and reverse bleed to get any pressure back. I got pressure now but the brake calipers are hanging up when brakes are applied. Only about 1/4 brake stays engaged but they get hot and you can feel it driving. If I open a bleed valve the release the pressure they are fine till I hit the brakes again, then they hang up till I open a bleed valve or let it sit for overnight, then they release also. I did change brake hoses and calipers seem to be ok. It is very hard to bleed these vehicles because the proportioning valve trips very quickly. The brakes worked fine before my leak. Any help would be great.

 

I'm really tired and not thinking straight, but did you say you pumped fluid into the calipers through the bleeder screw to get it to feel like a brake pedal again? that doesn't sound right to me man.
If you did I would say that probably broke them is my guess.
You prbably had no fluid left at the master cylinder after leaving it for a few weeks and it takes alot of bleeding to get the air out of there. that's why we bench bleed new masters before putting them on.

as far as direction....you can test the master on the bench, do a bench bleed see if everything holds.
to check calipers I usually just see if i can move the piston back easily, and if the piston is not leaking.
I would start at the calipers as the culprit.

Also on some older rides i've known the proportioning valve would stick and the rear brakes would stick a bit, you could hit the valve with a hammer and it would loosen up for a bit, valve needed replaceing ideally.

 

I did have the master cylinder off and did bench bleed it. I will check the calipers tonight to see if they are ok. My gut feeling is that the lines still have air trapped in them, but that really don't explain why the brakes would hang up though!

 

How does the brake pedal feel is usually a good indication of air in the system or not.
I don't think that would couse calipers to stick on though, check that the caliper sliders are in good shape and move freely.
grease them up on re-install if they check out ok, use good caliper lube.

then bleed bleed and bleed some more.

then if still no good. I'd look at the calipers as being bad....or still the proportioning valve.

 

Thanks for all the tips, it has been raining the past 2 days so I did not get a chance to check the calipers but I am going to do that asap. If the proportioning valve is bad were do I get one? I can't seem to find one for my model at to local auto parts stores.