OLD truck brake problem

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Old 11-11-08, 06:22 AM
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OLD truck brake problem

Hello. I just found this site and am wondering if you can help....

Donít know if you folks are old truck kinda guys or not, but Iím about at my witís endÖ.

I have a 1972 Dodge C600 grain truck with hoist. I have used this to haul topsoil and stone. I used the truck a bunch this spring, and then not at all for a couple of months. On one of my last trips I had the pleasure of meeting the local weigh-master who informed me (among other things) that I needed an annual inspection of the truck. So, I found a company who does inspections, took it to them and they did the inspection. All went well, but he noted that I had a little leak on the rear passenger side wheel where the brake-line attaches. He said not to worry much, it was just a little fluid and it looked like it really wasnít fresh anyway.

Fast forward that couple of months.

I went out to use the truck one morning and found that I had no brakes at all. Pedal went right to the floor with no resistance at all. I checked the master cylinder and found very little fluid. I filled it up and the pedal went right to the floor again. This time I looked at that line at the rear wheel and noticed all the fluid I had just put in was on the ground. OK, broken lineÖ.no problem.

My son-in-law wanted to know what I wanted for my birthday, so I told him that replacing that line would work for me. He said ďSureĒ and we went to the auto parts store. Replacing it took very little time. We filled the master cylinder up and bled all four wheels. No brakes. No pedal. We bled and bled. Still nothing. After about two hours, we gave up.

I called the guy who did the inspection to see if he wanted to come out and bleed the brakes, but he said he didnít do mobile work, but he did tell me of a guy who did mobile work, so I called him. He came out and said he could do the job. $50 and hour seemed very reasonable. We agreed that he would do the job during a regular workday, and I wouldnít be there to help. He worked about two hours one day and I met him there the following morning when we spent another 90 minutes. Still no pedal. I commented about the canister behind the seat that has always made a whooshing noise, but wasnít making that noise now. He said it was a vacuum assist can and that maybe we needed to bleed the assist mechanism under the truck in the seat area. He hadnít thought of that. We bled it. Didnít help.

He came back another day and said he noticed a little fluid around the read driverís side wheel. He took it apart and said there was a bad wheel cylinder. He replaced it. No better.

We had been bleeding the truck via the pump & hold method and he suggested a power bleeder, so he brought his out another day. We get brakes on the second or third pump, but no brakes at all when depressing the pedal the first time. After power bleeding, I noticed some fluid around the master cylinder so we replaced it too.

Same results.

It has now been about a week since we began and still no brakes on the first depression of the pedal. Another pump or two and we have solid brakes with lots of pedal.

Do you have any ideas or suggestions for me?

I bought this old truck because it was cheap, and I donít want a money pitÖ..but I canít even sell it with no brakes, so I kind of think we are beyond the point of no repairÖ.
 
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Old 11-11-08, 04:49 PM
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brakes

Has anyone adjusted the brakes? You say you have a solid pedal on the second pump,this woul indicate they are bled OK. RW
 
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Old 11-11-08, 05:01 PM
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First of all a 1972 truck is not old by my standards.

Sounds like you still have air in the brake lines. A solid pedal after pumping it up is an indication of air bubbles. Did you bench bleed the Master Cylinder? This gets residual air out of it before its installed. This air if not bench bled will be forced into the brake lines and will also have to be bled out. Keep at it,
 
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Old 11-11-08, 05:18 PM
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It sounds to me like the brakes need to be adjusted. If you have no pedal at first, and then you do. That sounds like you are pushing the pads all the way to the drum, and then on the next push of the pedal. You have pressure.
I think you need new pads,or just need to adjust the ones you have.



Travis
 
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Old 11-28-08, 04:00 AM
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I have a old Dodge truck with ABS rear brakes. I just put on new pads, shoes but then the pedal was really soft despite bleeding the brakes a few times. I replaced the master cylinder and now they will pump up but as soon as I start the motor the pedal goes to the floor. Also the ABS and emergency brake light now stay on. Any ideas?

Semi trucks for sale / Peterbilt Trucks
 
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Old 11-28-08, 09:23 AM
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As far as the "72 Dodge" that would be an adjustment at the brakes. The self adjuster may not be working = do it manually if you have good lining left. Should the adjuster be working you may try backing up and hitting the brake hard about ten times. If the self adjusters are working they'll ratchet up and set the brakes up for you.

The other problem when you see something similar is when the residual check valve (little hat shaped jobby just under the line hookup at the master cylinder) is shot. For a 4 wheel drum brake there would be one under each line hookup, For a front disc it would only be under the line hookup for the drum brakes.

That little thingy holds a residual pressure in the drum brake line and keeps everything in the brake taunt. It takes the pumping out of the brakes. Still the brakes have to be adjusted up as well, either manually or through the self adjuster.
 
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Old 11-28-08, 09:00 PM
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the vac booster has a secondary master cylinder on that system, it is probably bad as well. can't remember the exact name for it.

lofe begins when the kids leave home and the dog dies
 
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