I have a 92' Dakota, 2wd and rear abs. The brakes on this truck have been a constant issue but have only gotten worse. When the truck is running the pressure and amount of movement it takes to build pressure vary widely and randomly. Sometimes i can push the pedal all the way to the floor and build no pressure and the brakes wont work and other times it will build pressure instantly and brakes will operate just fine, and when the truck is not running the brake pedal is rock solid but if i hold it then start the truck it will sometimes sink to the floor gradually. ive checked for leaks and bleed the system several times. I have replaced both front calipers and pads, rear shoes and new drums and all hardware. I will add that the rear ABS servo block has been bypassed because it leaked and have yet to source a replacement. any help or ideas on what this could be would be nice. im not wanting to throw part after part at it.

 

Sounds like the master cylinder is bypassing internally.

 

And if it is, the booster is also dying; I'd replace both as a set.

(Fluid seeps around the rear seal on the master cylinder; brake fluid gets into booster; brake fluid eats rubber out.)

RwP

 

but i havent lost any brake fluid. the master cylinder is still full.

 

You don't when it's bypassing internally. Also, are you POSITIVE it's full? Could be down just a teensy tiny bit from passing into the booster, and not be down far enough to see it.

Again, I'd do master cylinder and booster.

Brakes are NOT something to cheap out on or be stingy IMO.

RwP

 

Text book master cylinder failing. Eventually, you will know the feeling from the old truckers song "Wolf Creek Pass". It talks about a driver heading down the pass when his brakes fail and stepping on the pedal is like stepping on a plum.


I was driving a truck for a living when this song came out.

 

Haven't heard that song in a long time. Thanks for sharing!
Oz