Hi,

I have a 1979 F150 supercab 2wd with a 400M. My problem is the proportioning valve is stuck to the front brakes only position.

It started like this; my break light came on and foot went to the floor. Low on fluid so I filled it and found a leak where the metal break line was rubbing the shock. Fixed this and could not get fluid back to the rear breaks. But I had front breaks. New everything except the proportioning valve as far as breaks go. Fluid will come out of the master cylinder but not out of the proportioning valve.

Since I ran out of time and need to work, I brought it to my mechanic to fix. He told me that the only source of this part is FoMoCo.... No remanufactured available. I looked around and this seems to be the case. Everyone that has one it is $150.00 (kind of High I thought) and it is a Ford part. If anyone knows of a cheaper source that I over looked let me know.

The Junk-yard is always a choice, but since it is the breaks I would like new or remanufactured. I kind of like to know the parts are going to work as planned as far as breaks go

Any suggestions would be welcome for an alternative source.

Thanks

 

I've had proportioning valves get off center really bad after a failure in the brake system. Many times you can get them back just by starting up the truck, and having someone push the brake pedal while you crack the lines on the master cylinder one at a time. Just have them watch the light, and when it goes out, tighten it back up. Seems to me you'd have to crack the line on the side of the cylinder that goes to the rear brakes so it would work the valve back to the right position, but I've had to play with both already to get the light to go out.

 

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Lastchance,

Let me see if I get this correct. Crack the line at the master cylinder. Or do you mean the line from the master cylinder and crack it at the point that it enters the proportioning valve? Or does it matter where you crack the line? I guess it would be easier from up top on the master cylinder.

Also, since the there is no fluid in the line from the p/valve to the rear breaks, will this affect resetting the p-valve.


thanks

 

I crack the lines right at the master cylinder. I forgot you didn't have any fluid to the back brakes, but it shouldn't matter. I'd try cracking the line to the front brakes first, but like I said before, I've had to go back and forth already between the 2 lines (on the master cylinder) one at a time to get it to work. You might also want to open the lid on your master cylinder and make sure you don't have a bad check in the reservoir. There was a guy here last week with a similar problem, went through 2 rebuilt master cylinders before he got a good one. Have someone push the brake pedal while you look in the open master cylinder. If you see fluid pushing up in the reservoir for a good part of the pedal stroke, the check valve is leaking.

 

Found that other post in this same forum. It's called "Poor brakes on 78". Take a look at it. It is on the next page or so down, depending on when you look at it again.

 

[updated:LAST EDITED ON 04-Dec-01 AT 04:29 PM (EST)] Is your brake warning light on? if so start er up and stand on the brake pedal with both feet as hard as you can. This should center the pro. valve. If the valve is bad NAPA has them I think around $50.00 if memory serves.
You probably need to bleed all the brakes to get rid of the air from running low.
Bear