Need Help! Serious Brake Problem in our FJ80

[Mike Serpe]

Need help....

Some time ago, my wife and I bought a lovely FJ80 here in the SF Bay, and restored it to new condition. It's a 1994 with the 4.2 6 which consumes too much gas, but otherwise is a great motor. Anyways, long story shorter, we shipped the car to my wife's farm in Greece and it gets used every summer now there. Well I have not been over there in the past two summers, but hope to get back over this year. My inlaws have a farm on top of a mtn, takes 20 minutes from the main city to get up there, or back down....all paved now thanks EU!

The truck is losing all brake pressure, but no fluid loss. We have changed the fluid, as well as the master cylinder twice. We changed the rear slaves as well...even though we found no leaks visible, and no fluid loss.

Still, it seems that if the brake system heats up, the pedal goes to nothing.

You turn the car off, wait 20 minutes, and its perfect again......so no bleeding required to get it back to perfect. Around town or on the highway, or on the trails it is fine....just down the mtn.

I told the ol man to use low range for safety, but he's still scared to drive it.

Any ideas? Do these boil their fluids easy? Do the master cyls get internal leaks? Vacuum booster, can that fail temporary if too hot?


HELP PLEASE.....inlaws will be very happy and so will wife if they can safely get their olives and grapes down to the market!!!

 

[BIGdaddy]

http://forum.ih8mud.com/80-series-tech

 

[expo80]

first things i would look at are the pads, make sure your e-break shoes are not dragging and also check to se that the caliper pistons are moving freely and not dragging any of these this can produce heat and degrade break pressure.

when this happens get under your truck and touch every caliper feel for the hottest one thats probably the one giving you issues (caution most likely very hot)

also might want to flush out the breaking system with all new dot 3 or higher break fluid, it maybe that you developed moister in your lines some how

 

[MotoDave]

When you say looses all brake pressure, you mean the pedal goes to the floor with no braking happening?

 

[Klierslc]

If there is not fluid loss my bet is on the booster. If you didn't use a toyota master cylinder, it is not unheard of for two in a row to be bad...... If the driver is riding the brakes, there may be nothing wrong with the system--it just gets hot and quits working.

 

[Mlachica]

Maybe riding the brakes going down the mtn. and overheating the brakes

Maybe you have air in your system. And for some weird reason only affects the braking when on a downward slope?

Spongy brake lines?

 

[chet]

take a really close look at your flex lines (the rubber ones) they may be soft and allowing the hot fluid to expand them rather than go into the caliper.

 

[Mike Serpe]

Brakes

OK,

will check the lines next and do the booster and see what happens.

the booster is rather pricey.....anyone know a good source for that?


The inlaws already flushed the fluid 4 times, and there is no air getting in at all. I got the master cyls here at Toyota of Marin and air mailed them to Toyota of Patra in GR....they installed and tested. It worked fine for 2 weeks, then same thing.

Inlaws took it back to Toyota, they kept it for four days, said we can't find anything wrong it must be your imagination.

4 days later, same thing happens again, inlaws scared, they put the car back in the barn and it hasn't moved since last september since everyone is afraid to drive it.



-ms

 

[adventureduo]

That's really odd.. i've never heard of an 80 doing that. I have no further suggestions than what has already been mentioned. If/when you solve or figure out what the problem is, please post up what it is/was.. i'd like to hear what's causing it. Scary.

 

[Hltoppr]

My FJ80 did that. Brake Booster. A new one from Toyota will freak you out with the cost. I got mine from www.cruiserparts.net and it worked just fine.

-H-

 

[Randy88FJ62]

Lspv?

Do you havfe a factory service manual? There are great instructions on diagnosing the braking system in there.

If your load sensing proportioning valve is not working corretly then your rear breaks might not be engaging at all making the fronts do all the work.

When you install the new brake booster make sure it has a hose that pulls vacuum. If you do not have that hose hooked up you haved manual brakes but that would feel obvious so I doubt that's the issue.

Also, new master cylinders need to be bench bled otherwise there will be air int he piston spring assemblies causing poor braking regardless of good pads and calipers.

Follow the FSM, inspect the fluid to make sure it isn't dirty and you should find the problem.

 

[Schattenjager]

You could always fly the pup and I out there with our 80 for a side by side comparison. We might not come home, however...
:elkgrin: