Strange new brake problem
Thread Starter
Melting Slicks
Joined: Nov 2002
Posts: 2,471
Likes: 2
From: 1993 Quasar Blue 'vert Scottsdale AZ
Strange new brake problem
This morning, I had to drive across town for an appointment. Car ran fine, cool, good gas mileage. About an hour or so after parking it, I started it up for the ride back on the freeway. The first thing that I noticed was a slight shimmy like a bad alignment. A few minutes later, I noticed that the coolant temp was about 205 and the oil temp was 241*. I also noticed a lack of power and was was only averaging 13 mpg while cruzing at 65 mph. Also, something definately smelled hot.
I stopped at a gas station. When I came out, she fired right up, but the "Brake" light was on. I pushed the brake pedal, and it went all the way to the floor! I checked the fluid level and it was full, but looked like mud (I changed the booster and completely flushed the system 2 months ago). I nursed it home, had a bit of brake at the bottom of the pedal. Temps went back to normal, car ran great, and everytime I used the brakes, they improved a little bit. They are almost back to normal now. What's going on?
I stopped at a gas station. When I came out, she fired right up, but the "Brake" light was on. I pushed the brake pedal, and it went all the way to the floor! I checked the fluid level and it was full, but looked like mud (I changed the booster and completely flushed the system 2 months ago). I nursed it home, had a bit of brake at the bottom of the pedal. Temps went back to normal, car ran great, and everytime I used the brakes, they improved a little bit. They are almost back to normal now. What's going on?
Melting Slicks
Joined: Aug 2003
Posts: 3,399
Likes: 394
From: Lakeville MI
The Booster may have been self-applying the brakes during your drive.
It doesn't take much pressure to generate very high pad and rotor temps with continous brake drag. 700-800 degrees C can easily be generated after 10-15 minutes of drag at normal speeds.
Ok I see you're in Arizona, even worse due to the high ambient air temps.
This could lead to possible fluid boil, or increased lining compressibility due to the extreme pad temperatures. Both would cause a long pedal, and poor brake effectiveness, but could recover somewhat after cool down and some re-applies. Did you smell the linings burning at any time?
You may want to check the booster output pushrod for over adjustment.
Your pads and rotors are more than likely toast, but they may recover with enough normal stops, say 200 or so. Any soot on the rotor faces?
It doesn't take much pressure to generate very high pad and rotor temps with continous brake drag. 700-800 degrees C can easily be generated after 10-15 minutes of drag at normal speeds.
Ok I see you're in Arizona, even worse due to the high ambient air temps.
This could lead to possible fluid boil, or increased lining compressibility due to the extreme pad temperatures. Both would cause a long pedal, and poor brake effectiveness, but could recover somewhat after cool down and some re-applies. Did you smell the linings burning at any time?
You may want to check the booster output pushrod for over adjustment.
Your pads and rotors are more than likely toast, but they may recover with enough normal stops, say 200 or so. Any soot on the rotor faces?
Last edited by tequilaboy; May 24, 2006 at 10:22 PM.
Thread Starter
Melting Slicks
Joined: Nov 2002
Posts: 2,471
Likes: 2
From: 1993 Quasar Blue 'vert Scottsdale AZ
I smelled something. There have been occasions over the last couple of months where I have suspected that the brakes are dragging, but I haven't checked it out. Also, when I replaced the booster, I took it to the shop to adjust those switches under the dash because the brake lights were continually on. Could they have over adjusted it? Also, no cruise control since the adjustment. Related? Time for a brake upgrade anyway, I guess. I suppose that dragging brakes could account for the high oil/water temps, lousy gas mileage?
