Brake Booster Troubleshoot

[sandcruiser]

So after driving all over some rough roads yesterday, when I got home last night, my brakes were marginally functional. When I depress the pedal, I get a faint "whoosh" or "hiss" sound, but very little braking power and the light goes on.

I checked the fluid, it was low, so I figured that maybe some had sloshed out or something...

this morning I added more fluid. It works a LITTLE bit better, but still feels terrible. It isnt' a pumping issue either as if I pump the brakes it works equally poorly.

Still have the wooshinghissing sound.

I'm now guessing that either A) my booster is bad B) my vacuum reservoir is bad or C) the very-expensive alternator vacuum pump is bad or D) the master cylinder is bad

I'm hoping it is the reservoir or the tubing in that area!

I'm dressed for work right now so I can't really dig around in that area -I'm short, there is no way I can get to the booster and whatnot without at least leaning on the very dirty fender. When I get some time this evening- how do I troubleshoot this? I'm guessing I can pull the tubing off of the vacuum end to confirm vacuum, that should be pretty easy.

I can look for a master leak. Also pretty easy.

But how to troubleshoot the booster?
And is there anything else I should be looking for?
Thanks in advance!

 

[Jan-78FJ40]

So after driving all over some rough roads yesterday, when I got home last night, my brakes were marginally functional. When I depress the pedal, I get a faint "whoosh" or "hiss" sound, but very little braking power and the light goes on.

I checked the fluid, it was low, so I figured that maybe some had sloshed out or something...

this morning I added more fluid. It works a LITTLE bit better, but still feels terrible. It isnt' a pumping issue either as if I pump the brakes it works equally poorly.

Still have the wooshinghissing sound.

I'm now guessing that either A) my booster is bad B) my vacuum reservoir is bad or C) the very-expensive alternator vacuum pump is bad or D) the master cylinder is bad

I'm hoping it is the reservoir or the tubing in that area!

I'm dressed for work right now so I can't really dig around in that area -I'm short, there is no way I can get to the booster and whatnot without at least leaning on the very dirty fender. When I get some time this evening- how do I troubleshoot this? I'm guessing I can pull the tubing off of the vacuum end to confirm vacuum, that should be pretty easy.

I can look for a master leak. Also pretty easy.

But how to troubleshoot the booster?
And is there anything else I should be looking for?
Thanks in advance!

I had/have lots of trouble with the brakes on my truck, so here is waht I would do: easiest to hardest (have a second person depressing the pedal):
check if the master is leaking on the outside
then take the vac hoses off the IN side of the canister, plug them with your finger, and see if you get the sound.
then the same on the OUT side (to the booster)
then at the booster

then bleed the brakes, maybe your fluid was just very low and you sucked air into the whole system

then take the master off, and see if it is leaking inside

I tend to think the booster and the vac pump will be fine, since neiter of them would lead to fluid loss.

finally the booster: idle the treuck for a few seconds, then take the vac hoswe off the booster. it should suck in air.

if all that turns out fine, you will have to take the booster off, which is a pain.
once you have it off, it is easy to open it with the clamp. look inside and see if the membrane is torn, or the seals are bad on the outside.

as I said, probably not the booster, since a dead booster would not lead to liquid loss
hth j

 

[sandcruiser]

I'm hoping that is right.... sorta thinking it *should* be the master cylinder... this booster/master was sitting unused for about six or eight months, so the seals could've dried out? dunno, but will hopefully find out this afternoon.

 

[Tapage]

I'm hoping that is right.... sorta thinking it *should* be the master cylinder... this booster/master was sitting unused for about six or eight months, so the seals could've dried out? dunno, but will hopefully find out this afternoon.

seals are a options .. The issue is, the DOT3 when you press the pedal goes to your booster damaging it. So also your booster ( the rubber diaphragm ) dried out, it meand loose of vaccum.

My avice ..

If you can, buy a new brake master, and buy the rebuild kit for your booster from your Toy dealer or aftermaket. Also if you can ( and you found it ) the rebuild kit for the vaccum pump it comes with 4 little carbon trowels ( palets . ? ) to replace the existing.

 

[sandcruiser]

ugh. I sure hope the booster isn't shot....
I guess I could always scab the booster off of the other 60, completely converting to a part-only vehicle...

maybe this is meant as a signal that it's time to do a hydroboost setup, spring the darn thing over, regear, and put on some 37s.... of course, maybe not also.

 

[Tapage]

ugh. I sure hope the booster isn't shot....
I guess I could always scab the booster off of the other 60, completely converting to a part-only vehicle...

maybe this is meant as a signal that it's time to do a hydroboost setup, spring the darn thing over, regear, and put on some 37s.... of course, maybe not also.

hey .. !!!

If you only need a brake problem to go with 37" I can't imagine if you broke a brierfield .. !

 

[sandcruiser]

Actually, before I can go to 37, I've got to get a new cruiser! I need my truck as a daily driver with clients, 37" is just too tall for most people to climb into.

It looks like it is probably the booster tested the vacuum last night, it works. There are no visible leaks anywhere. So later today I guess I dive into the booster to see what is happening there.

 

[Tapage]

Actually, before I can go to 37, I've got to get a new cruiser! I need my truck as a daily driver with clients, 37" is just too tall for most people to climb into.

It looks like it is probably the booster tested the vacuum last night, it works. There are no visible leaks anywhere. So later today I guess I dive into the booster to see what is happening there.

the vaccum kit it's really simple like I said, but replace it is dirty work .. the vaccum pump is always oiled by the engine oil.

 

[Eric Winkworth]

someone should do a write up on that procedure, sure is nice to have those write ups, the toyota manual has it all just very veg in some spots.