ccconor

In the last week, I have developed a relatively fast brake fluid leak; it only occurs while driving though, it does not leak while parked. I am unable to find anywhere where the leak is coming from. I'd expect to be able to see it but I can't find it for the life of me (I'm yet to jack the car up). Has anyone had this issue before/know what could be causing it? I've seen some talk about the ABS doing it but I'm not sure where to look to see if that's the issue. The car's brakes go all the way to the floor and barely stop the car unless the car is in neutral, If not in neutral I will roll forward slowly every time it revs. When the leak first started, I could fill up the brake fluid res, and then when full it would bring the car to a complete stop, since then this idea has stopped working.

EDIT: This is on a 1992 LS400

400fanboy

Dude. Please, for the safety of yourself and other people we all share the public road with. Do not drive this car again for any reason until you fix the brakes.

There are no "known issues" with the brakes on this car.

You say you can't find the leak... but you haven't jacked up the car... It sounds like you need to jack up the car and actually get under there. If it's losing fluid when you're driving, there will be evidence of that loss *somewhere*. Either a stain or a puff of smoke as it leaks onto something hot.

Any leak that is causing you to lose fluid and cause these problems should be pretty significant I'd imagine and should be pretty obvious once found. Whatever problem that was causing the leak is probably causing the current problem that adding fluid isn't fixing. It's probably some component thats busted and is causing the system to lose it's ability to hold pressure, or, allowing water and moisture to get into the system.

ccconor

Absolutely. The second I noticed it stopped braking instantly it was off the road. I’ve taken fronts and rear wheels off and can’t find a leak anywhere not even like a clue. I’m planning on fully jacking it up once weather allows it and getting a good look, rather than just with my tiny little small jacks.

400fanboy

Sorry if I was a little heavy handed, it wasn't really clear if you kept driving. Okay good

The brake system exists more than just in the wheel wells, have you looked around and under the engine for evidence of leaks? There are many components that exist there too. Brake booster and master cylinder. ABS module. In the engine bay and under the engine, there are various places to look for evidence.

ccconor

Yet to get under the engine but from just looking around at the top and looking where I can see with a flash light, I can not find any brake fluid! I’m guessing it’s a brake line somewhere

bradland

Brake fluid is hydroscopic.
Considering the age of the car there’s a good chance a brake line has rusted internally and failed. It could be anywhere under the car…

timmy0tool

iTrader: (7)

is there a visible fluid leak? how is the fluid level in the master cylinder reservoir?

if fluid level is fine, i suspect your master cylinder is to blame where the piston seals are gone, making the pedal ineffective to move the fluid through the system. of course there could be an outright leak so you need to get under the car and check everything (even the ABS).

Bylan

If certain there is no visible leak, I would also check the master cylinder as @timmy0tool said. With age, the seals inside can leak internally and it may be pushing brake fluid into the master cylinder vacuum line, which is why there isnt brake fluid on the ground.

deanshark

First thing.....DON'T drive it. "Behind every rolling ball comes a running kid" You might not be able to swerve quick enough and you definitely wont be able to stop the car.

Seeing how you were adding fluid then yes there's a serious leak, not just air in the system or a bad master cylinder. Every time you push the brake pedal the pressure is pushing fluid out. It wont leak just sitting there cuz you're not pushing the pedal. You need to jack up the car and look for the fluid, there's gotta be traces of it from spitting out while you're driving. Then follow it back to where it's leaking.

I went through this same thing with my old 94. It was actually the last straw which sent the car to the junkyard.
I had a rusted brake line near the right rear tire which started as just a pin hole but got worse. Eventually I got that brake line repaired but as soon as I got in the car, started it, put my foot on the brake pedal, and BOOM, there went another rotted line. Had it towed home, took the parts I needed, and off it went to the junkyard. (surprisingly I got $400 with it stripped)

I don't know how the under carriage of your car looks as for rust but if ya have one rusted line, there's gonna be alot more. (including fuel lines)

lamb03

when i first got my car my brakes were spongey but kinda worked for a little while lol, i had a small cut in a rear brake line they’re pretty short and easy to check behind your wheels