When's the last time the brakes were changed? The MC is full, but there could be a hole in the brake line somewhere and there is not enough pressure, slow leak of fluid maybe?

 

I've had the Jeep for 2 years, I've never changed it, so who knows when the last time was. Nothing seems to be leaking though.

 

Im in the same boat, I had no idea when the last time anything was replaced or fixed on mine, because the PO seemed to seriously neglect it. I pretty much fixed or replaced everything on mine in the first month or two of owning it, just so I knew when the last time it was done. If I were you, I'd just go ahead and replace the brakes. Maybe it doesn't need it, but maybe it does. Replacing them would give me piece of mind if I were in your shoes..

Oh, and leaking brake fluid isn't going to be like leaking oil. You probably won't see a puddle, or drips on the ground.. The fluid is dispensed through the lines when you press the pedal. That's when it will leak out..

You could have air in the brake lines. Have you tried bleeding them?

I had the brakes suddenly go completely out on me one time in my Silverado while I was driving on the highway.. I'll tell you it wasn't fun..

 

Best way I know to find a brake leak is to clean all the lines and fittings underneath really well. Then once they have dried get some athletes foot spray (the kind that leaves a powder) and spay all your lines and fittings. Then go for a drive, and when you come back then check the lines and hopefully you will see a wet spot where it leaked. Also check the slave cyls in the drums, and I've heard of the master leaking into the brake booster via the gasket on the back of it (although it doesn't sound like that's the case for you)
GOOD LUCK!!

 

You have a bad master cylinder.

 

IMHO, get a new master cylinder. KIK is correct, bad master. You have leak down/leak past where the fluid holds but sometimes it seeps/leaks past the seals. It can create a VERY dangerous situation i.e. no brakes. Change it out.

 

Yea, I want to replace the entire brake setup, but not for at least 6 months. I guess I can replace the Master for now. My ultimate plan is to get Rock Jock 60 with Wilwood brakes. I will also test for leaking! Thank you!

 

So I really haven't played with the Jeep much lately, so now I'm just getting around to this. I noticed the brakes are even worse than before. Look at the video below.

1992 Jeep YJ Brake Problems - YouTube

When hitting the brakes, you get this air pressure noise and the engine RPMs go up. I tried driving it and the brakes aren't soft, but they make that noise now and the Jeep barely brakes to a stop. What do you think the issue could be?

 

the air noise is a bad brake booster

 

This. Seems like you need to replace the booster and master cylinder.

 

Thought so!

 

Agree the booster is bad it would make the Rpm's rev also the air sound is typical I am just wondering how you are hearing it my hearing must be bad?

Or do you have some help pushing on the brakes while you are in the engine compartment?

Chief

 

Agree the booster is bad it would make the Rpm's rev also the air sound is typical I am just wondering how you are hearing it my hearing must be bad?

Or do you have some help pushing on the brakes while you are in the engine compartment?

Chief

hey chief,I know my hearing is bad but I have heard them before from the drivers seat