- Thread starter
- #61
I get what your saying, but the reason I had to vise griop my soft line was becasue the brakes locked up (that is when steam actually shot out of the bleeders back 2 years ago. It has been a long road figuring this out.
Brakes still randomly build pressure to cause undrivable dragging, everything replace
- Thread starter slickrock
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
I get what your saying, but the reason I had to vise griop my soft line was becasue the brakes locked up (that is when steam actually shot out of the bleeders back 2 years ago. It has been a long road figuring this out.
- Thread starter
- #62
Which check valve are you talking about? The only one I know of is in the master. The only thing that is the same is the hose from the engine and the plastic plug into the booster. Is that also a check valve?
Edit: That might be it. I have been using the same check valve in the entire time ( I think). I will order on of those first and see how it goes from there)
Last edited:
- Thread starter
- #63
You know, that booster chekc valve got me thinking. SO pulled it out a few minutes ago. I take it a check valve should not let a person blow air through it both ways (in and out). SO that will be replacd tomorrow.
Can someone school me on this? I know the heck valve only lets vac go into the booste and if it sin't working, wouldn't I loose brake pressure rather than get too much?
Can someone school me on this? I know the heck valve only lets vac go into the booste and if it sin't working, wouldn't I loose brake pressure rather than get too much?
the booster check valve works off of vaccuum, so suck on it to see if it works, don't blow on it......
ok, this is getting gross and weird at the same time.
anyhow, it should allow vaccuum (sucking) one way and not the other. This is what keeps the booster "charged" for a few safety brake pumps if needed when the engine loses power.
also, the check valve does nothing but give you those few extra emergency pumps of the brake when your car loses power, nothing else, it is not really needed but IMO a good idea for safetys sake, you could just run a hose to the booster and your brakes will work just fine as long as your engine is providing vaccuum.
HTH, noah
ok, this is getting gross and weird at the same time.
anyhow, it should allow vaccuum (sucking) one way and not the other. This is what keeps the booster "charged" for a few safety brake pumps if needed when the engine loses power.
also, the check valve does nothing but give you those few extra emergency pumps of the brake when your car loses power, nothing else, it is not really needed but IMO a good idea for safetys sake, you could just run a hose to the booster and your brakes will work just fine as long as your engine is providing vaccuum.
HTH, noah
- Thread starter
- #65
thanks for the PM. Basically, a working or nonworking check valve shouldn't play a part in brakes dragging.
Thanks NOAH, I just sucked on my check valve form both ends. It may sound dirty, but it tastes worse
burnt oil does not go well. As for sucking on it, I can suck through both ends and it does not seal.
Thanks NOAH, I just sucked on my check valve form both ends. It may sound dirty, but it tastes worse
burnt oil does not go well. As for sucking on it, I can suck through both ends and it does not seal.When I had the same problem, with the brakes in their dragging state, I had to crack the brake line union nut open at the master cylinder.
Just for a split second, but there was a noticable squirt of BF under pressure. It released the brakes and I drove home.
Something that affects the whole system would have to be the master cylinder, pushrods or pedal, wouldn't it?
Just for a split second, but there was a noticable squirt of BF under pressure. It released the brakes and I drove home.
Something that affects the whole system would have to be the master cylinder, pushrods or pedal, wouldn't it?
I did some google searching and as far as the check valve thing im sure its not the problem to your situation. but how you described it not closing when you suck or blow on it ,I would still replace it.
Go back and readjust your push rod, check pedel return spring mabe a stronger is needed to keep the pedel from pushing on the rod , move the brake line from the header , replace all your soft lines .
Go back and readjust your push rod, check pedel return spring mabe a stronger is needed to keep the pedel from pushing on the rod , move the brake line from the header , replace all your soft lines .
one other thing have you replaced any of the brake hardware in the drums . could the return springs be worn out causing the brakes to expand and dragg?
I know you said that they wern't hot to touch, but ....
I know you said that they wern't hot to touch, but ....
- Joined
- Jan 5, 2004
- Threads
- 143
- Messages
- 6,766
- Location
- Paint Lick, KY
- Website
- www.globalsoftware-inc.com
I'm not a brake expert but have worked on my share of drum brakes. A couple of things come to mind that you could check:
Brake shoe return springs?
Were they replaced? A weak set of springs could cause this problem. The randomness could be that the shoes hang a bit and the weak springs cannot retract them. Also are the springs installed correctly? One on the back side of the shoes and one on the front? May be a long shot but it's worth checking.
Incorrect shoe installation
Did the shoes get installed correctly? Several folks have posted in other threads that they thought they had the wrong brake shoes sent to them because they could not get the shoe to seat in the adjuster. Some report they ground them down to get them to fit! They actually either had the cylinders backwards (left adjuster installed on right side of truck) or they were trying to install the shoes incorrectly. Each shoe has a thick end that goes in the adjuster and the thin end goes to the other side. In my build thread I point this out with pics.
I also would replace the soft lines, they are the cause of a lot of grief...
Brake shoe return springs?
Were they replaced? A weak set of springs could cause this problem. The randomness could be that the shoes hang a bit and the weak springs cannot retract them. Also are the springs installed correctly? One on the back side of the shoes and one on the front? May be a long shot but it's worth checking.
Incorrect shoe installation
Did the shoes get installed correctly? Several folks have posted in other threads that they thought they had the wrong brake shoes sent to them because they could not get the shoe to seat in the adjuster. Some report they ground them down to get them to fit! They actually either had the cylinders backwards (left adjuster installed on right side of truck) or they were trying to install the shoes incorrectly. Each shoe has a thick end that goes in the adjuster and the thin end goes to the other side. In my build thread I point this out with pics.
I also would replace the soft lines, they are the cause of a lot of grief...
- Thread starter
- #71
That was one of the first things I replaced, again from a donor rig that had perfectly working brakes.
- Thread starter
- #72
I'm not a brake expert but have worked on my share of drum brakes. A couple of things come to mind that you could check:
Brake shoe return springs?
Were they replaced? A weak set of springs could cause this problem. The randomness could be that the shoes hang a bit and the weak springs cannot retract them. Also are the springs installed correctly? One on the back side of the shoes and one on the front? May be a long shot but it's worth checking.
Incorrect shoe installation
Did the shoes get installed correctly? Several folks have posted in other threads that they thought they had the wrong brake shoes sent to them because they could not get the shoe to seat in the adjuster. Some report they ground them down to get them to fit! They actually either had the cylinders backwards (left adjuster installed on right side of truck) or they were trying to install the shoes incorrectly. Each shoe has a thick end that goes in the adjuster and the thin end goes to the other side. In my build thread I point this out with pics.
I also would replace the soft lines, they are the cause of a lot of grief...
Funny, I actually used your web site to double check I had everythign installed properly. Yes to everything suggested.
I had to order a new check valve form the dealer. Will be in tomorrow since the generic one would not stay in. Also moved the brake lines outside the frame and disconnected every line in the front and blew air through it. Now I am vac bleeding and will do a manual bleed when I get some help. Hopefully I can drive it tomorrow and see if I found the issue.
- Thread starter
- #74
you took the old hardware from a donor??? I would say to look at it again.
this whole brake problem sounds like a wild goose chase.
I know for a fact it was working. I was around the rig for months before he did a disk brake swap. No issues whats so ever.
I am waiting on the booster check valve. They sent the wrong part today. Hopefully I can get it in the am and drive tomorrow.
I really hope it was heat. Still can't figure out how my brakes were cool to touch but I got a bit of steam off the fluid. Had to be the manifold.
Slickrock, Have you driven it at all since you moved the brake line?
When adjusting the brakes at the drums,How many many clicks does the FSM say to back off?
Have you tried to do more than what it says? or just back the off a little more.in the rear...
I was reading some where online that says to match the brake lining to the drum to see if they have the same diameter or curve . by taking he drum off and put the brake shoe in the drum to see how they mate.
how much of the surface actually touches.
303GARAGE
When adjusting the brakes at the drums,How many many clicks does the FSM say to back off?
Have you tried to do more than what it says? or just back the off a little more.in the rear...
I was reading some where online that says to match the brake lining to the drum to see if they have the same diameter or curve . by taking he drum off and put the brake shoe in the drum to see how they mate.
how much of the surface actually touches.
303GARAGE
another thing do you know if the linings have ever been fliud soaked before? as in brake fluid. I know you said that you didn.t see any leaking from the wheel cylinders, but.I can't remember if you said if the brake shoes were new.
I'm still thinking that maybe your hardware could be stretched . could have work on another vehicle ,but not yours.
They say you can drop the spring on the ground and here a thud there good but if they bounce and cling they are streched
due to heat and memory, if this is even true. Ijust read that somewhere in a troubleshooting site online, but you know
not everything you read is true..
I'm still thinking that maybe your hardware could be stretched . could have work on another vehicle ,but not yours.
They say you can drop the spring on the ground and here a thud there good but if they bounce and cling they are streched
due to heat and memory, if this is even true. Ijust read that somewhere in a troubleshooting site online, but you know
not everything you read is true..
Last edited:
brakes
From what you said about steam coming off the fluid ---I would fix that before I moved on, then could the hot or burnt fluid affect anything else?
Fix what you found already before thinking ahead to what else it could be---what if'll drive you nuts
"after driving for a week or two or on really long trips, my brakes tend to slowly build pressure until they finally start to drag on the breaks and I have to pull over and pop the master off and turn the push rod down. This is totally random. I can drive for 300 miles or 3, it totally seems to be random."
After that I honestly think you may be preloading the master cylinder
The booster assists by pushing a rod against another rod for the master cylinder if this is preloaded then you will gradually build up pressure each time you press the brakes until it locks up
The booster just helps you do this work.
I have all the brake stuff removed from my FJ right now but see if you can disconnect the pedal mechanism from the booster input and try and see if that takes care of it---IE pedal adjustment
if not the booster rod or master cylinder rod must be sticking bent or improperly adjusted but sticking or bent might explain the random behavior or it might be just how many times/how hard you hit the brakes
to get a problem on front and rear you would have to be affecting both the primary and secondary and about the only thing that could do that is the rod
If you think it's adjusted properly then possibly the pistons are sticking?
I don't know the particulars of the FJ system but this is all basic brake system stuff
I'd double and triple check that adjustment and freedom of movement then seperate the master cyl and booster and look for a problem in movement causing a preload there
Best of luck with it and let us know what you find so we can look smarter next time
From what you said about steam coming off the fluid ---I would fix that before I moved on, then could the hot or burnt fluid affect anything else?
Fix what you found already before thinking ahead to what else it could be---what if'll drive you nuts
"after driving for a week or two or on really long trips, my brakes tend to slowly build pressure until they finally start to drag on the breaks and I have to pull over and pop the master off and turn the push rod down. This is totally random. I can drive for 300 miles or 3, it totally seems to be random."
After that I honestly think you may be preloading the master cylinder
The booster assists by pushing a rod against another rod for the master cylinder if this is preloaded then you will gradually build up pressure each time you press the brakes until it locks up
The booster just helps you do this work.
I have all the brake stuff removed from my FJ right now but see if you can disconnect the pedal mechanism from the booster input and try and see if that takes care of it---IE pedal adjustment
if not the booster rod or master cylinder rod must be sticking bent or improperly adjusted but sticking or bent might explain the random behavior or it might be just how many times/how hard you hit the brakes
to get a problem on front and rear you would have to be affecting both the primary and secondary and about the only thing that could do that is the rod
If you think it's adjusted properly then possibly the pistons are sticking?
I don't know the particulars of the FJ system but this is all basic brake system stuff
I'd double and triple check that adjustment and freedom of movement then seperate the master cyl and booster and look for a problem in movement causing a preload there
Best of luck with it and let us know what you find so we can look smarter next time
Last edited:
- Thread starter
- #78
Gotcha. Rod is set as per FSM and it is the second booster and master. No way the rod would be bent two times the same way.
Fluid got hot without the rig moving, just engine running. I could sit on the brakes all day long, but without the rig moving, the fluid would never get hot (I would assume). S0 what makes fluid get hot wihtout turning wheels? It has to be receiving a heat source someplace. The only heat source is the headers.
I picked up the booster check valve from the dealer (36 bucks!) so a test drive this afternoon.
If the problem still exists, it may or may not happen today. I will keep updated as things change for the good or bad.
Thanks for all the responses.
Fluid got hot without the rig moving, just engine running. I could sit on the brakes all day long, but without the rig moving, the fluid would never get hot (I would assume). S0 what makes fluid get hot wihtout turning wheels? It has to be receiving a heat source someplace. The only heat source is the headers.
I picked up the booster check valve from the dealer (36 bucks!) so a test drive this afternoon.
If the problem still exists, it may or may not happen today. I will keep updated as things change for the good or bad.
Thanks for all the responses.
Fluid got hot without the truck moving!!?
Can you post a high res pic of the master/booster assembly and another pic of the hard lines going down to the frame?
PS - I still vote for the pedal and plunger not being adjusted correctly. If you disconnect the brake master plunger from the top of the brake pedal does the plunger push itself out past the pedal?
Can you post a high res pic of the master/booster assembly and another pic of the hard lines going down to the frame?
PS - I still vote for the pedal and plunger not being adjusted correctly. If you disconnect the brake master plunger from the top of the brake pedal does the plunger push itself out past the pedal?