perplexing brake problem?
Thread Starter
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Senior User
Joined: Apr 2003
Posts: 103
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From: Citrus County, Florida
perplexing brake problem?
I didn't find a column for brakes so I will just ask my question here! How do you know if your proportioning valve is bad? I had a rear wheel cylinder that started leaking and before I changed it out I had ran the resevoir dry a few times (3 or 4). After I changed the cylinder and bled the complete brake system twice my pedal is hard but it is like it is only using the rear brakes and barely slows down! When I was bleeding the brakes the brake warning light kept coming on and off even though I never let the fluid run low and I could hear the piston in the pro valve moving. Is it junk? or can I do something to fix it? I can't drive it this way and it is my only transportation right now! Any suggestions?
Thread Starter
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Senior User
Joined: Apr 2003
Posts: 103
Likes: 0
From: Citrus County, Florida
perplexing brake problem?
I did not pull any "thingy"! I have replaced most of the brake system at one time or another on this truck(paid $50 for the truck when I got it) and have never had any problems like this. The brakes were working awesome until I got the rear cylinder leak. They were working fine until I changed the cylinder and bled the system. It has had these things replaced within last two years: master cylinder, dr side caliper (bleeder broke off), dr side front brake lines (from proportioning valve to wheel), rotors turned, new pads, rear line from master cylinder to load sensor valve in rear, dr side rear line on axle, both rear wheel cylinders (one yesterday,one 6mo ago),drums turned,and new rear shoes! Basically it must be the pro valve since there isn't much else to replace. The rear "load sensing anti-lock valve" is screwed up also but it has been working other than the occasional rearend lockup if I am unloaded and hit the brakes hard, but I cannot find one of these to replace it with and the way the rear lines are I don't know how I could bypass it.
Post Fiend
Joined: Feb 2003
Posts: 6,940
Likes: 2
From: Eastern WA
perplexing brake problem?
A couple of thoughts: 1) When you bled the brakes did you start with the master cyl and make sure it was 100% bled before proceeding to the RR brake? 2) I've seen prop valves stick in the past when there was a failure in one half of the system. Try rapping on the prop valve with a hammer a bit to dislodge the slider. You may have to bleed again up front. I think this is what cartwright was getting at concerning the "pin thingy". Pulling on the pin thingy may release the slide if it's stuck.
Senior User
Joined: May 2003
Posts: 368
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perplexing brake problem?
Ok fellas, the real name for the pin thingy is the bleeder rod. It looks kind of like a finishing nail sticking out of the prop valve. You should pull the bleeder rod and hold it out with a spring clip or small vise grip while you bleed the system.
