Brake Problem

[luke_vs]

Hi all,

I been having some issues with my brakes over the last couple of months.
About two months ago I had my front disks and pads replaced. Ever since then, when I step out of car after about a 1/2 an hour or more of driving i can smell what i think is break fluid coming from the front driver side wheel (have not checked the other wheel).
This has been happening for the last two months.

The other day while driving for a long time on a hot day in heaps of traffic, i.e. lots of braking. The brake light came on. Also, the brakes failed like 80%. I had to put my foot totally to the floor to make the car stop. I took the car immediately to a mechanic and after lifting the front end we found that both the front wheels we're locked and spinning very difficultly. The mechanic rode the problem off as just overheating. The Master cylinder was very hot apparently.

The following day the problem went away. However, after the car warmed it seemed like the brakes were locking up, and i really had to push/power the car to keep it moving. I've had problems with power for a while, but just rode it off as old engine limitations. But I feel it could be linked to the brakes locking up.

Anyway, I got the brake system looked at by a caltex mechanic the other day and he flushed the brake fluid. He indicated the old fluid was dirty, etc and that the rear brake disk is getting thin. Other that, he said everything was good now.

Yesturday, after driving for about an hour I could smell the brake fluid from the front driver side wheel again. I popped the bonnet and found a fair amount of brake fluid leaked out had all over the sides of the master cylinder (with that crappy smell too). Master cylinder was hot but not steaming.

Was wondering if anybody has any suggestions over what the problem could be here. FYI car has done over 260,000km. I would like to be able to got to the mechanic and ask them to fix exactly what the problem is. Thanks in advance for any suggestions you may have

[hako]

Sounds to me like the caliper where the smell was coming from is not releasing the pad, and is holding this against the disc which is then heating the pad, which then heats the caliper to the point where the fluid inside the caliper boils and sends bubbles back up the line to the master cylinder where the pressure pops the cover off and brake fluid spills over the MC.
This could be caused by either the piston in the offending caliper sticking due to corrosion OR the caliper slides frozen solid and not allowing the caliper to centralise.....either will cause the pad to not release.
This would also cause the brake light to come on as the gases from the boiling fluid are compressible meaning the pedal has to compress this gas before it can work....and this make the pedal go down further than normal and triggers the brake inbalance switch in the MC.
If it was me, I'd replace the caliper and slides, bleed the system and go from there. However, if one caliper is this bad, it's a fair bet the others are the same, so maybe replace them all. New would cost quite a bit, from wreckers a lot less. If you are not going to do this job yourself I'd take it to a brake specialist as most mechs are not always good with brakes.
Good Luck.

[Brett_jjj]

Id be fitting a new master cylinder if the calipers are ok..It probably needs replacing now anyway with that many k's clocked up on it..It could be holding back some residual pressure in the brake lines when the pedal is released,this will cause the brake discs and calipers to overheat,this can cause the brake fluid to boil, causing it to overflow out of the master cylinder fluid reservoir.It would also explain why the master cylinder is getting hot.

[RX25SE]

If the calipers are OK it could be one of two problems.

The master cylinder is faulty and not allowing the pressure to return. Blocked compensating port in the master.
If the wheels are not free to spin (engine off) and you crack a bleeder nipple open and a small amount of fluid comes out and the wheel frees up, the master is crook.

or

The booster is faulty. A leaky atmospheric valve in the booster is like driving with you foot on the brakes (feels like a gutless engine). If the wheels are not free to spin after the brakes are applied with the engine running and you turn off the motor and pump the pedal a few times and the wheels free up, its a crook booster.

Either of these two faults will cause the brakes to overheat.

[luke_vs]

Hi all,

Thankyou for all you responses. I had look at the front calipers and they seemed fine. Opted for an after market master cylinder, $255, which a mechanic offered to install for $60.

After installing the new master cylinder and going for a test drive, the brakes were still locking up. The mechanic decided to have a look at the rear brakes and found another problem (the wheels were pretty much locked). The pads were almost gone and unevenly worn. Also, the calipers had moved out a long way. He pulled the calipers back easily and threw on a few cheapie brakes (charged another $90). The wheels turned much more easily now. All under an hours work!

That seems to have fixed the problem, fingers crossed. Once again, thanks for all your help, saved me from wasting alot of time running around.

Regards,
Luke

[luke_vs]

Car is running really well now and fuel economy is decent again. I am thinking of selling it now before the next thing goes. So, if anybody is after, or knows of anybody, after a VS Panther Mica Acclaim, get in touch with me...