ok guys i have spent counless hours on this withouy any luck! 02 f250 after about 5 or 6 miles the rear brakes act like there on like im riding the peddle bad enough it starts smoke the brakes! if i let it sit for a while it will release!i am at a loss its both sides to not 1! i have replaced all rubber lines on rear,calipers, rotors,pads.e brake is not on!
any other ideas would be much appreciated!!

 

Was it doing this before you replaced those things? If not, maybe a defective hose, though doubtful.

I think all diesels that year used a hydromax brake booster; my 2002 F350 7.3 does. (Hydromax = brake booster runs off PS pump hydraulic pressure). Maybe the master cyclinder is defective, sending boost to the rear brakes when it shouldn't. They're cheap enough - maybe just slap a new one on. Five cents says that fixes it.

 

ill give it a shot thanks john!

 

No problem, I hope that's it. Even if it's not, it wouldn't be the worst thing in the world to replace a master cylinder that's almost ten years old, considering what it does.

Let us know if that does the trick.

***

Thinking about it a little more; both sides at the same time is definitiely an important clue. Pretty much rules out sticking caliper or defective hose. Just wondering again if this started happening after the brake work, or was it doing this before. Could it be that the pads are just a little too thick? Did the pads/calipers slide right on, or did you have to force them over the disc? If they went right on, I think we're back to the lines being pressurized more than they should be with no pedal input. I sure don't know much about ABS, but maybe someone here knows if a fault in the ABS can ceate your problem. I have to admit that while the master cylinder could theoretically be the culprit, I've never actually heard of one applying pressure when it shouldn't.

Any real brake experts out there?

 

it started before i replaced all this stuff my truck actually set for about a year while i was using a company truck!i guess i am getting payed back for not using it! going to try the master cylinder tonight hoping its the problem! as far as the abs i dont know anything about it either but the light has been on since 2003?

 

I had a similair problem with one side of my rear brakes, it was so bad that the brake was smoking and I thought their was going to be flames coming out,The truck would come to a stop going down hill without my foot on the gas the rubbing was so bad and the smell was brutal.Thought for sure I had a stuck caliper.I had the brake line replaced as everything else in the brakes looked perfect according to the garage. Have had the smell once since but no other issues so far,though I am still skeptical that the brake line was the problem.

The most amazing thing was how hard it was to find a brake line for an 06 250. not even a local dealership had one in stock, i had to wait 2 days to get one in.

 

it was the master cylinder beleve it or not!!thanks for all the help!!!!!!!!!

 

Glad you fixed your problem. How much did it cost to replace the master cylinder if you don't mind me asking?

 

new one at auto zone was 80 bucks!!