GMC 1995 Vandura 2500 HELP!!!!!

This has all been done by a place called my little auto shop. I bought the

1st boost. He got the 2nd. It still did not work. He called GMC they told him he needed a diesel booster. I do not know if we did any harm with the first 2.

Shep wrote:

You could have bad calipers that a swelling up when they get warm and sticking. Replace the calipers.

Does your brake pedal return all the way? Is the spring hooked up? There MUST be a small amount of freeplay between the pedal pushrod and the master cyl. or what you describe will happen.

Dave

Yes, I understand that. You obviously didn't read what I wrote.

The brakes work fine for about 10-12 miles then lock up. When they cool down I can drive again till they heat up. The shop working on the van is stumped???!!! ______________________________________________

Some rear brake lines have a residual pressure valve. If the front and rear lines were interchanged, front brakes would not fully release.

Wendy & John. ______________________________________________

Getting in a little late. Has anybody suggested the proportioning valve?

Roy

Hi Roy and thanks to everyone that tried to help. We found out for some reason if I ride with the hood of my van up ( don't ask why I tried this) everything runs great. I put the hood down and the breaks lock up. Something about heat???!!! I took the van for a ride I put about 150 miles on it. With the hood down the breaks lock up. Hood propped up more cool air under the hood no problem ???!!!

Roy wrote:

Sounds like the master cylinder is bad. There are a couple ports in it that allow fluid to return into the tank as it heats up and expands. If they are plugged the brakes will come on as the fluid expands. Usually a little pressure and the crud comes out. However in your case either it is a large hunk of crud OR the piston is adjusted wrong in the bore. If you replaced it I would pull it off and check the length of the push rod. It may be just a bit too long Or maybe even the wrong master for the vehicle.

I tooke the van to GMC it was the rod from the master. it was to long. Bill replaces the master 3x's. As you can tell I know nothing about breaks, however Bill said he did. GMC fixed the problem.

Thanks to evey>> Replaced break system 3x's, from master cylinder, power booster down. Front

"Jim U via CarKB.com" wrote in news: snipped-for-privacy@CarKB.com:

curiosity?? 'Has a diesel break system'........does that refer to 1) belt driven vac. pump. 2) hydro boost power brake booster....just curious............kjun

Thought that might be the problem.

Hydro Boost. Kind of strange that GM used two different brake systems on the gas engine vans. My 95 has a conventional booster with the 4 wheel ABS unit under the van. Talk about a plumbers nightmare....