I have a 1984 toyota 1 ton truck. The brakes have been a bit squirrely since I bought it ten years ago. Now they seem to be engaging every so often as I’m driving along. What do you think: booster,master cylinder??? thanks
Worn drums can allow the self adjusters to keep tightening the brakes until they get hot and drag…Does the e-brake work? Do you ever use it? You might find it’s “tight” too, as the adjusters and e-brake are interconnected…If it’s not that (mechanical) then it’s hydraulic (master cylinder)…
The next time this happens crack one of the brake bleeder screws (open then closed) on the set that is locking up i.e. a front bleeder if the fronts are locking and/or a rear bleeder if the rears are locking. If this frees up the engagement, drive it until it happens again. This time undo the nuts holding the master cylinder to the brake booster (leaving the plumbing attached). If this clears the problem, disconnect the booster pedal rod and see if the booster push rod retracts. If the booster push rod remains too far out, try adjusting the booster push rod to the correct dimension. If undoing the master cylinder does not release the pressure, replace or rebuild the master cylinder.
Post back with further questions. Let us know your progress on this problem.
thanks for the reply. I have reason to believe that all 4 wheels are engaging. Strong smell around rear wheels while front are very warm and the last time this happened was last week 400 miles from home near Barstow Calif: the front end started to shake I pulled over and after 10 minutes I started up again and all was well with the world for another 50 miles or so. At which time there was no play in the brake pedal.So I got out and disconnected the vacuum line at the booster and cracked open slightly and momentarily a flare nut to the front brakes. still no play in pedal for another 10 minutes or so.
The rubber brake hoses, at the wheels, may have deteriorated internally. The debris will prevent brake pressure, in the hoses at the wheels, from returning to zero when the brake pedal is released.
Front wheels can get fairly warm and still be normal, rear wheels sure sound like a problem, after first checking hoses as hellokit suggests.Sounds like you’ll be in for new rotors and pads soon, along with a fluid flush, calipers and wheel bearing lube and adjust. That should take care of it.
This sounds impossible, but it CAN happen. Pedal pressure can expand the hose and the brakes engage. But when pressure is released, the hose(s) collapse and hold enough pressure on the wheel cylinders to keep the brakes engaged…The hoses can look fine externally…