GMC 1995 Vandura 2500 HELP!!!!!

Replaced break system 3x's, from master cylinder, power booster down. Front breaks lock after 10 miles of driving, I have to wait for them to cool down
before I can drive it. Again only 10 miles. Can not figure this out. Has a diesel break system, but runs on gas???!!!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Is it both front wheels locking, if only one suspect bad hose at the caliper. When this happens try cracking the line into the hydro boost if the brakes free up that is the problem, did this happen before all the work was done?

-
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi Shep It is both. We changed both hoses. I had a leak in my power stearing, it is part of the power booster. I have had break trouble ever since.
Shep wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I assume you know the theory of operation, the pb booster is the Hydro boost unit geting pressure from the p/s pump. Something is allowing the booster to apply pressure to the booster to apply the m/c. Loosen the lines at the mc to the front calipers, see if the brakes free up, if so the could be there is a misadjusted rod from the pedal to the booster and it gradually applies the brakes. Bad brake hoses could cause this but both of them would be rare and this did not happen till the parts were replaced, why were all the parts replaced originally? What both hoses to the calipers or p/s pump to booster? It may be time here to have a experienced mechanic to get involved in tracking down where the apply pressure for the brakes is coming from. You must attack this in logical order as outlined.

-
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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:

--
Message posted via http://www.carkb.com

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Jim U via CarKB.com" wrote:

cool
You could have bad calipers that a swelling up when they get warm and sticking. Replace the calipers.
--
Posted using the http://www.autoforumz.com interface, at author's request
Articles individually checked for conformance to usenet standards
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Front
down
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The breaks work fine for about 10-12 miles then they lock up. When they cool down I can drive again till they heat up. The shop working on ththe van is stumped???!!!
Hairy wrote:

--
Message posted via http://www.carkb.com

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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

Front
down
master
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Jim U via CarKB.com" 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. ______________________________________________
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Getting in a little late. Has anybody suggested the proportioning valve?
Roy
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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:

--
Message posted via http://www.carkb.com

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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.
--
Steve Williams

"Jim U via CarKB.com" < snipped-for-privacy@CarKB.com> wrote in message
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks Steve I will pass this on the Bill ( the man working on the van ) on Monday.
Steve W. wrote:

--
Message posted via http://www.carkb.com

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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 eveyone that helped.
Hairy wrote:

--
Message posted via CarKB.com
http://www.carkb.com/Uwe/Forums.aspx/gmc/200508/1
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

curiosity?? 'Has a diesel break system'........does that refer to 1) belt driven vac. pump. 2) hydro boost power brake booster....just curious............kjun
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

long.
did.
and
belt
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....
-
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thought that might be the problem.
--
Steve W.


"Jim U via CarKB.com" < snipped-for-privacy@CarKB.com> wrote in message
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.