Hi All,

I'm stumped on a brake issue with my 2001 Dakota 4x4 SLT 4.7l AWD...

When the engine is off, and I pump the brakes, the pedal will firm up. As soon as I start the engine, the pedal goes all the way to the floor.

What I've done so far...

I've bled the brakes - 3 times 3 different ways... 2-man method of pressing the brake pedal to force fluid thru each wheel, vacuum method of pulling fluid thru each line from each wheel, and pressure method of forcing it thru from the master cylinder. At this point, I have no bubbles and clean, clear, new fluid at each wheel. I went in order from right rear to left rear to right front to left front, in order of longest to shortest break lines.

I've replaced the master cylinder, bench bled it, twice, once with plugs in the fittings and once using the bleed kit with hoses... and then bled the system again. Still no change.

So at this point I am wondering if this is booster problem, or an ABS pump problem.

What tests can I do to help identify which direction to go next?

Thanks in advance for your ideas and suggestions.

 

Without touching the pedal it goes to the floor?

If so, yes. Your booster has failed. There are valves internally that apply vacuum to the diaphragm when you push down on the pedal. That valve has likely failed.

 

No, the pedal remains in what I would consider normal position until pressed. When pressed, it goes almost entirely to the floor. It will stop the truck, but there is almost no resistance in the pedal at all until it gets most of the way down.

Compared to when the engine is off, after 2-3 pumps, it only moves 2-3 inches and has significant resistance.

 

OK.

Rear drums or discs?

You need a DRB to fully bleed the ABS system. You could still have some air in it.

 

That sounds about on par with mine, even after ditching the ABS and re-bleeding all 4 corners 3 times.

 

Rear drums / pads and front rotors / pads all have at least 1/2 life on them.

I'm not familiar with DRB...

 

The DRB is the computer used by Dodge to access the PCM and other diagnostics on the Dakota - including the ABS.

Basically it is a very fancy scan tool.

Are the back brakes adjusted properly? Don't rely on the self adjusters.

 

That's one thing I didn't check. I removed the drums and I can feel them grab when bleeding, but I haven't checked the actual adjustment.

Thanks!

 

I finally had time (and dry weather) to look at this and yes, it was an adjustment issue. One back wheel had a broken "lever" that wasn't even attempting to adjust anything. I replaced the adjustment kit and things are getting back to normal.

Thanks for the tip! It was very much appreciated!

 

Thanks for the update