05 Duramax with Sticking Brakes!!!

[Redram99]

So everything has been working great... until Saturday.

I used the truck to move my travel trailer and when I got home and unhooked the trailer I noticed the truck was quite hard to move and I could smell brakes.

Upon further investigation I find that all four brakes are dragging slightly. More brake pressure on the front tires than on the rear.

Could it be the proportioning valve?
Does anybody know where the prop valve is?
When I bled one front brake the other front wheel released its pressure as well.
ANy other ideas?
Thanks

[bigdaddydiesel]

I would recommend trying to flush your brakes, especially if you have never done it before or if it has been a while..

Here is a DIY for ya to help you along if you have not done it before...

D.I.Y. "One Man" Brake Fluid Change/ Flush

[jc1843]

You probably have a bad master cylinder-- when the master cylinder piston gets sticky with "crud" it will not return to the proper place which blocks off the fluid return port in the cylinder bore. When heat builds up in the brake system, the fluid expands and has no where to go, so this starts building pressure and applys the caliper pistons.

Opening a brake line will usually release the pressure, and it will be OK until it builds pressure again.

Hope this helps.

[Redram99]

Thanks for the ideas.

Could it be the propotioning valve?

Does anybody know how they work or where it is located on the truck?

[Redram99]

Fixed it!!!

I removed the master cyl and pulled it apart. Everything looked good.

A mech friend reccomended that I do the following before changing parts.

So then I blew out the entire brake system with comp air and did a full bleed on the system and ran about a half gallon extra fluid through the system.

No more sticking brakes.

[seth999]

yup when you tow often the fluid breaks down alot faster causing sticking parts due to buildbup and it can cause other things like extra heat etc.