Hey all, sorry for the all caps heading, but i drove the 56 sunliner to meet a friend about 40 miles from home for dinner. When i got here, the brakes wouldnt release. Symptoms



Pedal very firm

Brake light on even with footoffbrake pedal

Pedal returned to normal height

Car can move but labors, obvious extra drag from partially engaged brakes



I tried stomping on the pedal a few times and moving the car back and forth to no avail



HOWEVER...once i shut the car off the pressure released and all is well.



The car has the factory power brake booster. Im wondering if its a bad vacuum check valve? If so, can i disconnect/plug the vacuum line and make it home (about 40 miles)? if i do that, im assuming i just wont have power brakes, but all else will work?



Or should i call for a tow truck now?



PLEASE HELP!



Ron



Or is it likely something else?

Ron Grove

Wauconda, IL

You may have an older brake line that hascollapsed from the inside. It's happened to me before. In that case it was the rear brakes and the line had to be replaced. Are the brakes dragging even though you don't have the pedal down?

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

Brakes are dragging without the pedal depressed. The flex lines are only about 3-4 years old (4 tops), so i guess id be surprised if thats it?



Brake lights stay on when brakes are dragging; pressure was released when i shut engine off (car had been idling for about 10-15 mins while i tried other stuff, and brakes didnt release)

Ron Grove

Wauconda, IL

Ron,

Have you done any work to the brakes or exhaust system lately? I have seen the symtoms that you are describing a few times before. Once from a brake line to close to an exhast the other from overly tight brake adjustment.

Heat from a draging brake can make the system self apply giving a firm pedal and draging brakes.I compounds because of this.  Let it cool and it should get you home but you will have the same problem once you get home.

Your sugestion on the booster or master being the problem could be a problem. I let the car cool see if that fixes the problem. Then try the vacuum hose off.

Cheers

Warren      

Grizzly (Aussie Mainline)

You can try disconnecting the booster and see if that fixes the problem.  Beyond this, a collapsed flexible brake line still comes to mind although only being four years old and failing would be unusual.  Unless the hose(s) you bought sat on a store shelf for sixteen years before you got them.  I’ve found that twenty years is about the life expectancy for those.  If they are made offshore, then life expectancy may be even less depending upon the mix on the rubber components being used.

Lorena, Texas (South of Waco)

I suspect that the piston in your master cylinder is cocked in it's bore and can't return to it's non-engaged position. take a wrench (or something substantial) and use it to rap on the master cylinder- sometimes that will dislodge it. Replace it ASAP. /Duck

BOO- YA!!!

Hey guys, thanks for the thoughts.... Some additional info:



No recent work done on the car. Last time i worked on the brakes was when i flushed the fluid 2 summers ago. Evryething else on the car is working fine.



If the piston was cocked in the mc, wouldnt the pedal be loose/sloppy? In my mind, it would have to be cocked in the depressed position to hold fluid pressure, right? But the pedal had no play in it whatsover; it was firm and at the top of the travel, there was no looseness or play that would indicate that the piston was cocked at the bottom. Of the bore. Am i thinking about this right?



The hoses were bought from tee bird prods, and usually they have good parts, but no idea of the origin or age for sure.



Like i said, weird thing is that once i turned the car off the pressure released very quickly. Thats what makes me think its the check valve, but i have a tendancy to fixate on what i think the problem is without looking at all the facts...


Ron Grove

Wauconda, IL

Ron

If I understand you correctly the brake problem (locked brakes) will disappear when the engine is turned off and engine vacuum to the booster drops off. As was suggested by Ted you can disconnect the hose from the manifold to the booster and cap it. Then you can drive the car with non power brakes until a fix can be found. Another thing to try with locked brakes is to open the wheel cylinder bleeders ( last resort). When you do find out what it was, let us know. Pete

Yes, that is what happened. Car was idling for 10 mins or so with bbrakes effectively locked up, and pushing on the pedal, rocking the car back and forth didnt free them. Pedal was very very very stiff, at the top of the travel (rest position), and the brake lights were stuck on.



I shut off the car and walked around to the trunk to get out the tools, and the brake lights were off, and when i put the car in neutral it rolled freely.

Ron Grove

Wauconda, IL

Hey guys, quick update. Came out from dinner and all was back to normal. I disconnected the power brake vacuum line and plugged it just in case. Car ran great all the way home, brakes worked fine (except w/o power assist, obviously), so not sure if that was the root cause or not. May be able to dig into it this weekend, although im not too sure how to start diagnostics on something like this...



I sincerely want to thanks everyone who took the time to read this and chime in on it. You were all very helpful, and i truly appreciate the time you all took to read and respond.



THANKS!

Ron Grove

Wauconda, IL