Cosworth

What happens when brake fluid starts to boil? What are the results of such failure? Thanks.

johng

Brake fulid typically boils due to moisture that has creeped into the system (or old stock fluid/not performing routine bleeding). When this happens you don't stop well, so hold on to your a$$. Avoid this altogether by using better fluid/lines and bleeding often.

edit; spelling


[Modified by johng, 11:11 AM 5/20/2002]

madhatter

The pedal goes to the floor. Also known as fade. It is a little different than pad fade, because cooling the pads makes the fade go away. Once the fluid is boiled, bubbles have formed in the brake lines and must be bled out. Braking power is severly reduced until you have bled the lines. An easy solution to this is to use a higher temp fluid, though I have never been able to boil even a synthetic, off the shelf DOT 4 fluid. My pads have always faded before I could boil the fluid in the lines.

Cosworth

After hearing you guys answers, I think my brake fluid boiled on Friday (instead of my master cylinder going bad). Anyway, here's the story.

On Friday, I was running around in my Civic w/ stock brake system (front disc, rear drum). The temp was around 85+ in my town (probably a lot more in the engine bay)... I drove for about one hour under stop-go-traffic. Everything is good so far. I park the car for about 1 hour, then started to head home. About 2 miles into my drive back home, the pedal decides to sink when steady pressure was applied. I had to pump to get the brakes to bite + e-brake to stop.

Fast forward to Monday. I didn't drive the car at all over the weekend. I ran tests on the booster to rule it out as a faulty equipment. (Test as shown in Helms manual). The M/C still is "full" and no sign of brake fluid leakage anywhere. I drove it today and it works as if nothing had happened before.

So, is this just a case of brake fluid going bad? Or, is my M/C going out? I mean, the car brakes fine now. I want to say that the symptom is temperature related.

Any more comments or helpful advices? Thank you for all your help.

-Sean
p.s. I apologize as it's not really competition related. But if anyone knows anything about brake fluid boiling, it would be you guys.

Track rat

My guess is that you have a master cylinder problem. While parked with the car running, pump up the brake and hold it steady for 10 seconds and watch for the pedal to sink, if it does the master cyl may be bad.

Unless your fluid is absolutely shot, you have to get the brakes really hot to get boil related failure.

Madhatter: "I have never been able to boil even a synthetic, off the shelf DOT 4 fluid. My pads have always faded before I could boil the fluid in the lines."
I agree!! In episodes of track related brake fade, usually the pads are giving up, not the fluid. I think most guys believe it is the other way around.

[Modified by Track rat, 7:42 PM 5/20/2002]


[Modified by Track rat, 7:44 PM 5/20/2002]

DB2-R81

When was the last time you completely flushed your systems brake fluid? And what type of brake pads are you using?

Cosworth

I tried this this morning. The brake is firm even after 30 seconds of steady pressure.

The brake pads are autozone cheapies. brake fulid will be changed today. (don't know how many miles on the fluid to tell you the truth. I just got the a few weeks ago, but with no brake problems until last Fri.)

DB2-R81

With inexpensive pads you may have temporary glazed your rotors, driving conservatively for a few hours will clean your rotors up. Don't skimp on pads if your going to drive your car hard. Flush your brake fluid and bleed your system of any accumulated air and moisture. And check your booster and associated lines for vacuum leaks. Also the heat may have allowed the vacuum lines going to the booster too expand and loose vacuum, are they in good shape, are the hose clamps tight?


[Modified by DB1-R81, 12:09 PM 5/20/2002]

johng

Sounds more like a master cylinder to me having gone through a similar failure. My two cents is to bleed your brake lines and see if the problem goes away. If not, replace the master cylinder ASAP.

Track rat

AUTOZONE pads???!!! Are you using Kool Aid for brake fluid too?

Case closed.

Warren

If we told you what Todd Reid was using for pads, you'd probably have a heart attack.

He runs on Pep Boys pads. $11 a pair.

Warren

Cosworth

Dude, it's for street... it's not like I'm running the car at the track.

Track rat

Understood. But I would recommend Autozone pads for a lawnmower.

qtiger

Agreed. You wouldn't use Autozone oil for your engine, don't use their pads on your brakes.

tonydatyga

um, if you boiled your fluid... i believe your problems wouldn't go away after an overnight resting session. Should still have issues due to bubbles. If its not the m/c, I would check for a partial pedal pressure leak somewhere. Sorry, no idea where.

siisgood00

Man you guys sounds pretty ignorant. Have you ever used the autozone pads?! Do you realize they are Performance friction pads. Do you realize that PF is a HUGE name in racing. Do you realize that the PF pads from auto zone have a higher CF than stock pads. Do you realize that the PF pads have a lifetime warranty. We are talking a wear item here! I run PF pads on the street and they are great!

VWkila

I don't know if my problems are similar but hear my story.

Recently, I swaped my '92 CX rear drums with Integra disks. Along with the breaks, I swaped master cylinder and booster off of ITR as well as 4040 proportioning valve. I also put Goodridge steel lines. My pads are AEMs.

When I first get in the car, brake pedal has very litle pressure. After I pump it, pressure comes back. I start the engine, pressure dissapeares. When I pump it again several times, pressure comes back.

Car stops fine, but I REALLY have to push far. This happens on every stop light. I have to pump it to build the pressure.

I followed the factory service manual to see if my booster or MC is bad, but everything checks fine.

Track rat

I tried Autozone pads on my tow vehicle several years ago and they were absoute crap. Apparently they've found a good supplier now!

siisgood00

Maybe the compound is different for trucks/cars. By no means is the auto zone PF's pads on par with Hawks or Porterfield and such, but for the money and the warrenty they are a great street pad for those who drive like grandmas on the street. Id rather save my P+ for the track.

Crazydave

Performance friction like other brake pad manufacturers produce more than one compound.

we use PF pads on the stock car .. they are incredible pads.. every race the rotors glow red hot... and the pads never fade! (I think they are the PF 'z' rated pad)

Cosworth

That definitely sounds like a m/c problem to me. The "problem" that I had is completely gone now that I drive like a grandma and since the ambient temp has been under 70deg for the past two days. I'm guessing that my fluid is crap and m/c is fine.

btw, wasn't it a b!tch to make the ITR m/c and booster fit with your non-abs '92 CX? I am going with RS 15/16" m/c & booster if and when I upgrade mine. These RS m/c & booster is a true bolt-on unit (1" units are not from what I've heard).

Track rat

Quote from Todd Reid:

"for aggressive driving you must get the "QS ceramic enhanced Nascar Select". these puppies are around $50 for the Type R pads... they last me about 5-6 weekends of track RACING."

FYI, Not $11 Granola pads.

4WDrift

A bad master cylinder will have a slowly sinking pedal with light to moderate pedal pressure as the fluid leaks around the shredded piston seals, but can seem fine with a quick heavy foot because then the seals are forced out enough to close the holes.

Gary

Warren

Oops. That sandbagger!

Warren

Track rat

Warren, by the way...congrats on the sponsorship! Those shocks look like they should be on a fighter jet