Brake Failure

[CRR_1987_911_GR]

As I was driving home on the freeway today, I started hearing a squealing noise coming from the right front of my car (a 1987 911 Carrera), which then would stop upon lightly touching the brakes, but would return about 10 min later. The brakes themselves seemed to be working fine, until the moment I went to pull into my driveway, at which time I applied the brakes and the pedal went all the way to the floor. A quick release and pump of the pedal and the brakes were back, thankfully. When I got out of the car, I put my hand up to each of the wheels and the right front was definitely hot. What I’m wondering is if there could have been some air in the right front brake line that was causing the caliper to rub and this generated heat exacerbating the problem, or if there is another more serious problem. Right now I’m considering replacing the brake fluid to see if this solves the problem. Any other things I might want to look for?

Thanks for the help!

[David E. Clark]

There are really only four possible causes:

1. Brake fluid is very low: Check the master cylinder fluid level and fill to the marked level.

2. The Master Cylinder is bad: Replace master cylinder. *This would also cause the calipers to not retract and explain the excessive heat.

3. Air in the hydraulic system: Bleed hydraulic system

4. Large leak in brake hydraulic system: Locate and repair leak

[Jims5543]

Could the front right caliper be bad? Possibly hanging up on the rotor and overheating causeing the pedal to go soft when braking?

Is the car pulling at all when there are no brakes applied or when braking?

[CRR_1987_911_GR]

Thanks for the replies. The brake fluid level was fine and no signs of any leaks. The caliper may quite possibly be the problem. When I jacked up the car, the right front wheel was very difficult to turn, suggesting the caliper is still engaging the rotor. Is this sufficient evidence that the caliper is bad, or could the sticking still be due to air in the brake line?

[Jeff]

Your caliper needs to be rebuit or the inside of your brake line is failing and not letting the fluid flow back.

[masraum]

My guess is that the caliper was dragging. Rebuild both front calipers, replace the rubber lines at least in the front, and replace the fluid. You'll be fine. Usually the thing locks up so that you can't drive. Maybe yours created enough heat to get the fluid too hot.

[eapcpa]

Very likely that the caliper needs to be rebuilt and you need to check the piston for pitting. Brake fluid absorbs moisture over time which causes corrosion inside the system. When enough corrosion builds up it gets stuck in the caliper bore and will not retract when you release the pedal. We are talking fractions of an inch. Annual flushing of the fluid helps prevent the corrosion. If the piston has any pitting that is present after buffing with emory cloth or similar ultra fine sandpaper (1500 grit) the piston needs to be replaced. Only the outside surface needs to be smooth where it contacts the caliper seal but if you are taking it out clean it up. Rebuild both while you are doing it and replace all of the fluid with quality stuff. Good luck.