Ugh now I have brake issues :/

[Chattzx]

Okay guys, my brakes have been randomly locking up on me when driving to the point where my car will barely move. I will have to turn off the car and sit for a while and then you can hear them letting go of the disk after a few minutes of sitting. I don't even know where to start looking to solve this issue. Also my brake pedal is insanely stiff along with my abs light being on. Oh and to tell everyone how hard they were locked up when I pulled into my garage smoke was billowing out of all 4 wheel wells. Any help is appreciated.

[robomatic12]

Check the pedal assembly for anything sticking. Check the master cylinder for leaks/fluid level. Check the brake booster vacuum lines to and from the intake plenum. When was the last time you bled the brake fluid? How long has this been happening for?

You will need to remove the wheels and check the calipers for fluid leakage, then you will need to compress the pistons and see if they travel outwards when you pump the pedal.

To me, it sounds like the brake calipers are getting frozen out and not retracting back. A set of rebuilt calipers, or rebuilding them yourself, is probably the fix. But please diagnose it first.

[Chattzx]

Yeah I have a feeling its the master brake cylinder, since it would be kinda odd for all 4 calipers to seize up at once.

[robomatic12]

Yeah you are correct, I forgot you mentioned all 4 brakes were smoking. Very strange issue. Hopefully it is not a problem with the ABS unit.

[Chattzx]

Well since I have had the car the abs light has always been on and it has never worked.

[robomatic12]

Do you hear a buzzing/whirring noise which is coming from the ABS unit?

Go through the ABS diag as shown below in the factory service manual, so we can figure out what is wrong with the abs system.

http://www.300zx-twinturbo.com/cgi-bin/ ... t&total=56

[J30tChumpCar]

IF no work has been performed between now and the onset of symptoms the most common issue that causes this is oil contamination of the brake fluid(usually mistaken power steering fluid for brake fluid jug)

Take off the cap and inspect the rubber seal, if its swollen up you have oil in there and first thing will be a new master and complete fluid flush.

Just a thought.

[Chattzx]

Wow sir you are correct the rubber seal is swollen

[J30tChumpCar]

Well thats sorta good news, the problem is now apparent and you can go from there.. The bad news is (over time)oil in brake fluid swells any rubber parts it contacts, so at a minimum, the master is toast.
Buy 1(or 2 to be safe) QUARTS of brake fluid, bench bleed/install the new master, then, get a strong leg helper and bleed the brake calipers of no less then 1 of those quart jugs, 2 quarts to be absolutely certain you have flushed every bit of the contaminated fluid.

90% of the time the contamination remains localized to the master and seeing where the ABS unit is located there would have to been LOTS of oil to get to it or past ...

[Chattzx]

Thanks for the help I have a feeling I may have accidentally poured a little bit of ps fluid in the reservoir so im gonna bleed the brakes today and see how it goes

[J30tChumpCar]

The master is already toast and a safety hazard, not to mention you will contaminate the rest of the system, bleeding is not going to fix this until the master is replaced, the swollen seals are permanently damaged.

IF you insist on bleeding, first remove the fluid cup to drain and refresh before forcing that gunk through everything.