Front Brake Issues - 88 B150 Van

Greetings all,

I recently acquired a 88 Dodge B150 Cargo Van. It's a 318 V8, auto w/power disc brakes in the front. It runs pretty well and I have spent this past week fixing a bunch of little issues along with rebuilding the steering coupler in preparation for inspection.

The only issue left before inspection is that the front brakes pull noticeably to the right when you first apply them. It seems to moderate and act normal after the initial "pull". In other words it's more of an initial grab to the right vs a constant pull.

Today I took off the front wheels to see what was up w/the brakes. I concentrated on the left using the logic that it wasn't "clamping" enough, causing the pull to the right.

The rotor looked pretty good along w/the pads. Caliper was dry w/no leaks. To see if I was getting good fluid flow I cracked the bleeder (after attaching a bleeder hose and bottle) and stepped on the pedal once. The quantity of fluid coming out seemed normal. So I decided to replace the caliper.

Flushed out the old cruddy fluid w/fresh, replaced the caliper and then while bleeding I then noticed that when you step on the brakes the fluid flow was OK, but after a couple pumps of the pedal, no more fluid would come out. It was as if the bleeder had been closed, but it hadn't. In other words the pedal was stopping at approx the normal "applied" position.

However sometimes if I held pressure on the pedal awhile, or pushed really hard on it, then all of a sudden a little "bump" would be felt and then the pedal continued down toward the floor and fluid flow returned. Then for a couple pumps everything seemed OK after which the flow stopped again, the pedal again acted as if the bleeder wasn't open (again it was) and we start all over from the top of this paragraph.

So I pulled the master cylinder off and found that the whole area of the piston where the power booster pin rode was very rusty. In hindsight I knew it probably wasn't the master, but going with perhaps it was sticking, I replaced it anyway. I'm glad these parts are rather inexpensive.

I should note that while the master was off I pumped the pedal several times to see if any stickiness could be felt. Everything seemed fine.

Bench bled the new master. After replacing it I'm in the same boat as before. Fluid flow for a couple pumps, then nothing. Hold pressure or push like heck and it starts again for a couple more pumps. Repeat ad-nausem.

Took it out around the block and it does seem a bit better than before, but still not correct. The right side still grabs before the left. And in addition I now have the brake warning light on all the time. I suspect the proportioning valve is "off center". If I pull the wire/connector from the valve, the light goes off. Thus this issue lies there.

So after my rather wordy explanation, my questions are how do I "recenter" /reset the proportioning valve switch and more importantly I'm open to any suggestions as to why I'm getting the intermittant fluid flow described above? Also any other input related to possible causes and/or troubleshooting tests would also be most appreciated.

Thanks in advance to all who reply.

Regards...................George

TTT

There is a special tool I believe to reset that switch. You local dealer may be able to do this for you.

As for the pulling you could have a bad caliper or maybe a collapsed hose on the right side.

Hello All,

I resolved the pulling brake issue today. Turned out to be the left front brake hose was slightly crimped by the bracket/band that they wrap around the center of the hose to attach to the frame. As the hose looked original, I suspect it has always been a bit crimped/restricted since new, but perhaps a little swelling of the hose was all that was needed to cause the restriction to increase enough to cause an issue. The original hose bracket basically was a "J" which had the hose squeezed to keep it in place. The aftermarket replacements bracket had a nice full circle/360 degrees around the hose w/no need to crimp it tightly to get it to stay.

FWIW I received a little troubleshooting trick from a mechanic friend I thought I'd share. He said to raise the wheels off the ground, have an assistant step on the brake while you apply pressure to the tire/wheel, attempting to spin it. Release the brake pedal and the wheel should almost instantly start to turn. If there is a delay, slow release, dragging, etc, then if the caliper is known good, it's the hose. (or at least some restriction in that line somewhere)

So now all I'm left with is getting the proportioning valve recentered/reset as the brake light is still on. I will investigate this further but welcome any additional suggestions on this issue.

Thanks to everyone who contributed. It was very much appreciated.

Have A Great Week!

Regards.............George

George,

I had the brake light stay on in my 2000 B1500. Come to find out that the switch was the issue. It went bad because I had pressed the pedal all the way to the floor when bleeding the lines. Thus, the switch got stuck and stayed on. The switch is located just above the brake pedal. It's a very mechanical switch as well. A metal housing, plastic button, a spring and contacts to the wires. You either need to get it un-stuck or find a replacement. Give that a look at too.

Stev

I got the proportioning valve recentered today after finding a cutaway drawing of the valves internals. Combined w/my sequence of events, this allowed me to figure out what had happened and what was needed to fix it.

The light had come on by opening a front bleeder and stepping too hard on the brake pedal. Thus the valves piston had slide toward the front fluid outlets due to the reduced pressure on this side of the valve. To get it slide back, I hooked up a bleeding bottle w/some fluid to one of the rear bleeders and opened it, removing pressure on the "rear" side of the valve. I stepped on the brake pedal until it was down to front brakes only. Then I gently pushed a little harder, using the front brake/fluid pressure to push the valve back toward the now unpressurized rear side. It worked like a charm actually.

So I'm assuming that if the light had been triggered by the rear system losing pressure vs the front, you should then be able to reset it by opening a front bleeder and using the pressure of the rear system to recenter the valve. FWIW.

I hope this helps someone. Once again I appreciate the input. Thanks again.

Regards................George

That's good info to know George..thanks!

Yes, a good bit of info. Who would guess a simple fix like that?

Originally Posted by stev

Yes, a good bit of info. Who would guess a simple fix like that?

Yes it did turn out to be pretty simple. Based upon the research I did on the net and all the "maybe-might-could-should work" advise I found, you would have thought it was rocket science or something. Glad I was able to find that cutaway pic/info on a proportioning valve which helped a lot. On that note I'm trying to post this info here so anyone else who wants this can get it. However the system won't let me add a URL. Am I not worthy yet being a newbie here?

I was told the dealer has a tool that inserts in place of the valves switch and "catches the piston during the resetting process". What I didn't mention above was when I was pushing the piston back toward the rear side of the valve, I actually stepped a bit too hard/went a bit too far and actually got the piston slide back past center and into the rear position. (Light went out for a second and then back on). I had to reverse the process and use a gentle slow pedal pressure to get it back to center. I imagine this "special tool" stops the piston movement when a spring loaded center pin (or similar) slides into the pistons "v" notch. FWIW.

Anyhow, between the trick to test the brake hoses and learning how to recenter a proportioning valve, this van's certainly been a learning experience. Even after wrenching on my own vehicles for 30+ years, I'm still learning.

BTW the van did pass inspection today. Good for two years. I doubt I'll have it that long so all is good, at least for now.

Thanks again all. Have A Great Weekend!

Regards...............George