Brake Issues
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Brake Issues
Having issues with my '77 F-250 4x4 High-Boy (351M). The brakes went out while my wife was driving it and it seemed like the problem was the master cylinder. After replacing that and bleeding the system it still has a hard pedal. I've been told that it could be both a vaccume issue as well as the booster being bad. Which is the most likely culpret? Also while looking around trying to trace vaccume lines on the motor. I found a small line on the passenger side of my Carb that angles down with anouther line down into a small plate in the top of the head. One is broken completely off. What are these lines? Hopefully someone can shed a little light on my problems. Thanks
Ryan
Ryan
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A hard pedal can be for a few things.
Has the truck been sitting a while?
Caliper pistons can seize inside their bores and it takes massive pressure to move them once this has happened.
I suggest a complete inspection of all the entire brake system.
There is a booster test to verify whether it works or not.
1) Shut engine off
2) Pmup brake pedal 5 times (until all the vacuum has been evacuated) keeping foot on the pedal
3) with foot still on pedal....start the engine..
4) what happened to the pedal ? did it go to the floor ?
or
did it go to floor and rise back up a little ?
I'll see if I can find a illustration of the carb for you to point out the vacuum tube
Has the truck been sitting a while?
Caliper pistons can seize inside their bores and it takes massive pressure to move them once this has happened.
I suggest a complete inspection of all the entire brake system.
There is a booster test to verify whether it works or not.
1) Shut engine off
2) Pmup brake pedal 5 times (until all the vacuum has been evacuated) keeping foot on the pedal
3) with foot still on pedal....start the engine..
4) what happened to the pedal ? did it go to the floor ?
or
did it go to floor and rise back up a little ?
I'll see if I can find a illustration of the carb for you to point out the vacuum tube
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From: lino lakes, mn
sounds like the auto choke heat tube and clean air tube I take the one on the passenger side of the carb is right under the air horn(top) towards the rear the other one goes to the back of the choke housising and both go down the exhaust manifold ? the one to the choke housing is heated air for the automatic choke the one from the top of the carb is the supply line for this air you can drill these out of the manifold and replace them with 1/4 inch brake line or just put an electric choke stat on the truck and do away with that stuff but you have to plug the hole where the line from the choke housing goes to the manifold or you will have a vacum leak
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Thanks for the info.
As for the booster check the pedal is always hard can't even pump it up with the truck off. It does stop but not quickly I've been having to drive it due to it being my daily. The most it sits is a week or two, when I ride the bike to work.
As for the lines in the top of the carb I'll try and plug the one broke off to see if it helps. Thanks for the info.
As for the lines in the top of the carb I'll try and plug the one broke off to see if it helps. Thanks for the info.
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Still no brakes
I've been playing around with different things that I believe were causing vaccum leaks on my ford I fixed the auto choke as well as a small vaccum line that runs over to the passenger side and up the firewall inside the cab with anouther larger line. I also replaced the check valve on the Booster which still to my schgrin has not rectified my brake issues. I still have a hard pedal. It is almost impossible to pump up even off. I am reluctant to replace the booster not knowing exactly what the problem is. Any othere suggestions or is the booster the culpret?
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Sounds like either seized caliper pistons/wheel cyl pistons to me.
IMO, Time to jack the truck completely off the ground to do a manual spin the wheel (apply the brakes) brake test to see what is actually working and what isn't.
You can also check bleeder screws for line pressure to verify system.
IMO, Time to jack the truck completely off the ground to do a manual spin the wheel (apply the brakes) brake test to see what is actually working and what isn't.
You can also check bleeder screws for line pressure to verify system.
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From: Montana
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I haven't checked that yet but I'll do that next. I've also been throwing new u-joints in it today. So i'm streached a little thin and my helper pulled a no show but i appreciate the all the info.
Ok I did try the test of pulling the check valve while she was running and yes there was quite a bit of vaccum so does that mean most likely the booster?
Ok I did try the test of pulling the check valve while she was running and yes there was quite a bit of vaccum so does that mean most likely the booster?
Last edited by Plummer_62; Sep 23, 2006 at 04:58 PM.