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'78 F150 won't bleed to rear brakes

  #1  
Old 09-24-2004, 10:01 AM
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'78 F150 won't bleed to rear brakes

Hi all,


I know I've cross-posted this to the brake forum but I really need an answer quick.

Right before I took three weeks to swap the engine in my '78 a hard rear brake line blew. I left it alone as I knew the truck was going to be laid up for a few weeks. This week I replaced the line and one other, along with a the wheel cylinder at the right rear corner. I tried to bleed the system last night but no fluid will come out at the bleeder screws. I disconnected the line further upstream to see if I had a blockage, and still no fluid. I suspect nothing is getting past the proportioning valve.

According to the Haynes manual the proportioning valve should reset itself with a gentle application of the brakes after bleeding...but I can't bleed it. Can the rod inside the proportioning valve get stuck and close off the rear brake system, preventing any fluid from getting past?

There was no blockage when the line blew as great quantities of brake fluid drained out of the bad line, and the master cylinder would empty the side that serves the rear brakes even if I refilled. Now when I filled it to bleed the system, no fluid left the MC.

How can I reset the proportioning valve to allow fluid past?

Thanks,

Tim
'78 F-150 Ranger
 
  #2  
Old 09-24-2004, 10:31 AM
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some people on here have mentioned about pulling or pushing the little *** on the front of the pv. i dont know anything about it, just making a suggestion i've seen come up from time to time.
 
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Old 09-24-2004, 10:49 AM
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the rod is where the wire goes onto the p valve, remove the wire and push on ythe pin. they get sticky after several years.
 
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Old 09-24-2004, 12:07 PM
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Get on under there and pull the pin out and have someone pump your brakes. That should do it.
 
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Old 09-24-2004, 01:06 PM
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that would make you a "pin puller"
 
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