What happens when brake fluid starts to boil?
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Re: What happens when brake fluid starts to boil? (Cosworth)
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]
edit; spelling
[Modified by johng, 11:11 AM 5/20/2002]
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Re: What happens when brake fluid starts to boil? (Cosworth)
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.
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Re: What happens when brake fluid starts to boil? (madhatter)
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.
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.
#5
Re: What happens when brake fluid starts to boil? (Cosworth)
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]
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]
#6
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Re: What happens when brake fluid starts to boil? (Track rat)
When was the last time you completely flushed your systems brake fluid? And what type of brake pads are you using?
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Re: What happens when brake fluid starts to boil? (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.
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.)
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#8
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Re: What happens when brake fluid starts to boil? (Cosworth)
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]
[Modified by DB1-R81, 12:09 PM 5/20/2002]
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Re: What happens when brake fluid starts to boil? (Cosworth)
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.
#11
Re: What happens when brake fluid starts to boil? (Track rat)
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
He runs on Pep Boys pads. $11 a pair.
Warren
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Re: What happens when brake fluid starts to boil? (Track rat)
AUTOZONE pads???!!! Are you using Kool Aid for brake fluid too?
Case closed.
Case closed.
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Re: What happens when brake fluid starts to boil? (Track rat)
Understood. But I would recommend Autozone pads for a lawnmower.
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Re: What happens when brake fluid starts to boil? (Cosworth)
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.
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.)
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.)
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Re: What happens when brake fluid starts to boil? (Track rat)
AUTOZONE pads???!!! Are you using Kool Aid for brake fluid too?
Case closed.
Case closed.
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Re: What happens when brake fluid starts to boil? (siisgood00)
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.
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.
#18
Re: What happens when brake fluid starts to boil? (siisgood00)
I tried Autozone pads on my tow vehicle several years ago and they were absoute crap. Apparently they've found a good supplier now!
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Re: What happens when brake fluid starts to boil? (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!
#20
Re: What happens when brake fluid starts to boil? (siisgood00)
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)
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)
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Re: What happens when brake fluid starts to boil? (VWkila)
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.
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.
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).
#22
Re: What happens when brake fluid starts to boil? (Warren)
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.
"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.
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Re: What happens when brake fluid starts to boil? (Cosworth)
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
Gary
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