So I was driving my '87 f150 today and the brake pedal mashed to the floor when I pulled in to the parking lot. All the way at the bottom there is braking if I press hard. The rear abs light is on, and it has done that off and on for awhile, but it goes away shortly after starting. But the other weird thing is that the parking brake light stays on even after letting the parking brake off.

I haven't done anything to the brakes in 6 months, and it doesn't seem to be loosing fluid, that I could tell after a quick inspection.

I did put new coil springs in the front but I was carefull not to put any tension on the brake lines.

Any Ideas on what to check. I am thinking maybe brake booster??? I don't even know how to check that. I have to move in a week so this has to be fixed quick.

Thanks again guys.

Blindlightguy

 

No not the brake booster, if you are not losing fluid then it would be the M C.

The parking brake light means you have unequal pressure between the front and back break lines.

 

Would the unequal pressure be a rabs realted problem or still the M/C?

Is putting in a new M/C a difficult process?

thanks,

SubFord.

Blindlightguy

 

You have rabs on an 87?Sometimes, the biggest problem is getting the lines off the old M/C without messing them up and loosening the bleeders at the wheels.

Make sure you bench bleed it first and then you may need someone else to pump the brakes while you bleed them.

 

Yeah it has RABS. Infact that light comes on as well.

I don't know I might just take this one into the shop. I just don't know if I want to deal with all the bleading what not. Plus I don't have much time to deal with all this.

Blindlightugy

 

i bet it is a rusted brake line.

especially under the drivers door back.

 

I had the same problem. is the pedal really soft like it doesnt come up that much? I had 2 boosters like that. they seperated inside and i had to take them off and play around with them a little. But i also had a mc go it only took me about half an hour to put a new one on. you may need a flairing tool if the line breaks. but then you gring the stub of a line off and get a drill bit the same sice as the outer diamiter of line. drill out the line and flair it bcak on the line. it is only 2 bolts and a nut to get it off the booster though. the booster is easy to take off too. tkae off the mc and there are 4 nuts under the pedal inside. they dont really rust in the cab so they are easy to take off. then disconect the pedal and it goes right out. When you buy a mc there are instructions on how to bench blead it. it is really. if you get a mc with out a resivour then you have to carefully pry the old one off the old mc. it pops off though. then push it back on to the new one. put it back in and blead the breaks. that isnt hard or long. a few minutes. I wouldnt take it to a shop they will charge you alot more than its worth. mcs arent that expensive and it isnt that much work for you to do it your self.

 

Having both the ABS light and the service brake light on constantly is triggered by low fluid level in the master cylinder reservoir. I'm not sure how it would measure unequal pressure between front and rear when there are no pressure sensors in any of the brake lines.

 

The Break Indicator will come on with unequal pressure from the Duel Break Warning Switch on non ASB systems. You are right on the ABS systems.

quicklook2 is more than likely right too about the "i bet it is a rusted brake line.

especially under the drivers door back."

 

I learn something new every day thanks!

 

Quicklook2 wins the prize.

With some better light, it became apparent that the rear line right buy the fuel pump has rusted and busted.

I am thinking I will have the guy in the shop accross the street do it. I don't own any of the flare tools or bending stuff, and I don't plan to do this kind of work much in the future.

Blindlightguy

 

yeah for my correct guess!

so i am fixing my cousins 92 f150 5.0 truck by replacing the frozen starter. with a large screwdriver i could not turn the gear and as soon as i finish and start the truck for the first time in 2 months, i step on the brakes and one of the brake lines that is all springy under the master cylinder has rusted at the frame.

got to love living in the rust belt!

i knew what it was right away and got a bucket to catch the drip.

the starter was a bosch lifetime, and it had the bolt and wire instead of the spade that always gets corroded.

 

I have the same truck but it is rust free. the only place i found even some suface rust was the hood and the brake line going down to the t on the drivers side. I got the black line stuff from auto zone that is suposed to hold up to rust better.