I have a 86 BroncoII. My brake pedal sticks and will not return all the way. I've replaced the pads and checked the shoes, and recompressed the pistons inside the calapers. I'm thinking that it might be the master cyclender, but is there a way to be sure that is the problem??? please help.

 

sounds like it could be the master cylinder..have you checked to make sure the fluid is full? does the pedal come back up if you pull it up?

 

yeah i think it is too, but it might also be the brake booster. i need to cheack to see if its pulling a vacume. yeah the master cyclinder does have fluid in it, and i re-blead the brakes today. im going hopefuly tomorrow to get a new master cyclinder. ill keep you posted on my progress. thanks. if you have anymore ideas please feel free to post them. and the pedal does return if i pull up on it.

 

Sounds like the master cylinder (and it's probably allowing air back into the system). I would also check the booster to make sure it's okay as well, but even if it was toast, I don't think it would cause this problem.

 

My 86 did EXACTLY the same thing after i got it back on the road,but mine sat for a while,it was the brake booster in my case,i replaced the master cyl and no changes,i had a scrap ranger sitting here and swapped that one out with it,solved the problem in my case.
My son has an 87 B2 all cut up and just used for the woods,his brake booster was leaking vaccumm real bad,he took my old one from my 86 and for the heck of it sprayed WD40 in the interior side of the booster and worked it loose,he's still using it in his with no problems but i wouldnt recommend that for a daily driver thinking the WD40 may hurt the seal or something in there.

 

well i did cheack the booster today, it is fine. Im going tomorrow morning to get a new master cyclender. if that doesnt fix the problem, then it has to be the calipers. one of the pistons could be defective. but who knows. thanks for all the help on this problem. i did find a nother one today as well though. i just noticed that i have a slight miss in the engine. what should i do to try to fix this? there are new plugs and wires already in it. and i ran a can of restore through it today. where should i look next?

 

Check the cap, rotor, base timing, vacuum lines, distributor pickup, tfi module, fuel filters, fuel injectors, Idle air control/Throttle body (cleanliness), MAP Sensor, EGR, O2 sensor. Pretty much in that order.

 

new cap and rotor. the base timing was set last week. all new vacume lines. fuel filters and injector are new as well. the 86 doesnt have a map sensor. and EGR checked out last night.

 

Usually its the booster that will cause this problem, had it happen on my '76 had to drive with two feet one to press the pedal and the other to pull the pedal back up once you resumed driving

 

well it is the booster. i had to order one. so i will have it fixed soon. and to fix my last repliy, it has a MAP but not an EGR. the MAP check out.

 

Uh. Okay. My understanding was that the '86 & '87 (but not the '88) 2.9 FI 1st Gen Bronco IIs had an EGR valve and that all BIIs had a MAP sensor. Weird. Someone please correct me if I am wrong!

 

on 83-87, i beleave its called a pivit valve, but it does the same damn thing as an EGR. i might have the name wrong.