A little bit of background.
A few weeks ago i noticed one rear wheel locking up constantly when braking. so pulled the drums and one of the springs on the right side had broken. So i got new hardware and replaced both sides hardware. Then I noticed that the left rear wheel cylinder appeared to be leaking (probably caused by compensating for the broken side) so i replaced it the next day. (last year i replaced both wheel cylinders with one ton dually cylinder upgrade).

Now for the issue.
a few days later i noticed that there was some sort of oil or fluid on my left FRONT wheel well. and it appears to be coming from the brake lines. the brake booster and master cylinder both remain dry and it doesn't look like the they are leaking.

i had my wife pump the brake pedal while i looked to see if i could see it coming from somewhere but i cant. The pedal gets nice and firm when truck is not running. and when it is running it can be pushed all the way to the max. however when driving the pedal can go to the floor and the the brake and ASB light will come on, but when you just tap the pedal they go off again.

any idea what could be going on? best way to trace a leak like this? anybody expeirnce something similar?

also i noticed when pumping the brake pedal I can see the brake booster flex slightly, is it supposed to do that?

 

Well you have to find that leak....

First check for loose fittings, Maybe you get lucky.

Then it's on to broken stuff. I'd start with the worst rusted looking new.

 

there isn't any rusted stuff or loose fittings, that's the problem.

any tricks or tools or dyes to help track down leaks in hard lines?

 

Having a spare foot to step on the pedal, while you are looking for where the fluid is going.

Also, be sure to check the vacuum line to the brake booster. May have a blown M/C.

 

I'm having a similar issue with my 1993 Dakota 5.2L 2WD. I replaced the master cylinder and booster. Bled the brakes and get good pedal and pressure until I start the engine. With engine running, pedal goes to the floor. Shut it off and pedal pressure returns.

Any ideas???
Todd

 

Keep bleeding it.

 

Do you think that will make the pedal return any higher?

 

The pedal should come all the way back up. There is a mechanical stop under the dash. If you have low pedal height when you step on the brake, (but, actually GET good brakes) adjust the rears.

 

Well I called my friend back over and bled the heck out of them. Went through 2 bottles of brake fluid and all kinds of cloudy stuff kept coming out of the rear lines. Once it started flowing clean the brakes worked fine. I adjusted the brake light so it works fine now. Remember, I had no brakes at all when I got the Dakota. What I didn't realize is the pedal does feel a little soft but still stops the truck just fine. Must just be the nature of the beast.

Thanks for all the help.
Todd

 

Drive it for a few days, then bleed the brakes again. May still have a bit of air in there. Just needs to work its way out.