Need help with bleeding brakes!
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Senior User
Joined: Jun 2003
Posts: 294
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From: Vermont
Need help with bleeding brakes!
Hello, I have a 1986 F-250 and I can't get the rear brakes to bleed. I started on the rear, like you're supposed to, and they wouldn't bleed so we just did the fronts so we could move it around and such. We have heard that it could be the proportioning valve, but that is brand new. It's not the lines, because they're brand new stainless lines. The blocks in the rear are also brand new along with the wheel cylinders. We heard that we should push the little pin inside the proportionng valve in until we heard a click, which we did, but it still didn't work. We also tried weighing down the bed, thinking that it was that brake sensor thing on the axle, but that didn't work either. Yesterday I filled the rear lines, because we thought that maybe it wasn't sensing brake fluid, but that was to no avail. We are about to give up and I'd figure I'd ask you guys who have helped me considerably on the rebuilding of my truck. Thanks. 
Senior User
Joined: Sep 2004
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From: FLOWER MOUND,TX
it may take a while with replacing the wheel cylinders also...was the master cylinder brake fluid going down at all when you were bleeding the rear???i know on my 78 theres a pin on the front of the proportion valve that needs to be in the out position (via small needle nose vice grips) to bleed..acording to my manual for 78 but i'm not sure on a 86
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
With the lines being replaced, it might take a while. Try disconnecting the line at various places and making sure the fluid comes out. Especially right before and after the prop valve, if you're suspicious of it.
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Senior User
Joined: Jun 2003
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From: Vermont
Fluid comes out of the proportioning valve fine. You can also easily blow through the whole line, so it's not blockage. Tonight we bought a vacuum pump and tried that. We had already filled the lines manually, and we got a very little bit of fluid and that is all. There should be very little air in the lines. Only in the junctions where I couldn't fill manually. We are about ready to sell it 
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Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
If it comes out of the prop valve ok, and the lines are all clear, then you just haven't bled it enough. I don't know what else to say, really.
If you disconnect the line at the wheel cylinder, does fluid come out of it?
If you disconnect the line at the wheel cylinder, does fluid come out of it?
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Senior User
Joined: Jun 2003
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From: Vermont
UPDATE: We got the pin in the proportioning valve to where the brake light was off and then we unhooked the load sensor thing from the axle and folded it up. That let a little fluid to the wheel cylinders but not like it is supposed to. We then simply bypassed it and they bled great. Well that took about 4 weekends worth of troubleshooting to narrow down. Then we rebled the whole system and decided to test it out in the driveway. Well as soon as I backed up and hit the brakes, the brake light came on I thought we had it figured out! anyone know why it came back on after we bled all the air out of the system? Also, is it ok to leave that load sensor thing bypassed or not? Thanks, Austynn
I thought we had it figured out! anyone know why it came back on after we bled all the air out of the system? Also, is it ok to leave that load sensor thing bypassed or not? Thanks, Austynn
Posting Guru
Joined: Dec 2002
Posts: 1,113
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From: Remsen, NY
I'm not sure if I can help with your specific problem but take a look at this:
http://www.motiveproducts.com/
I think it's only about $50 for the bleeder and about $20 for the Ford specific connector. You may even be able to get the bleeder with just the connector and not have to pay extra.
Maybe this would push out whatever is causing the problem?
Is there something in the master cylinder that has to be reset manually (pressure switch)?
http://www.motiveproducts.com/
I think it's only about $50 for the bleeder and about $20 for the Ford specific connector. You may even be able to get the bleeder with just the connector and not have to pay extra.
Maybe this would push out whatever is causing the problem?
Is there something in the master cylinder that has to be reset manually (pressure switch)?
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Joined: Sep 2004
Posts: 263
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From: FLOWER MOUND,TX
isn't there a ball inside the perportiang valve??when i opened my system to put new brake lines on it took a few brake aplications to seat that ball..(felt it pop in through the brake pedel)then brakes felt fine..maybe thats is why your light came on???just a thought
