Troubleshooting - Brakes
Symptom-driven guide to diagnosing brake pedal problems, brake noise, vehicle pull during braking, and pulsating brakes on the Porsche 924, 944, and 968.
Difficulty: Moderate3 min readApplies to: 924 · 944 · 944S · 944S2 · 944 Turbo · 968
Introduction
This troubleshooting guide is intended to help identify and repair problems with the brake system. Symptoms covered:
- Brake Pedal Goes to Floor When Depressed
- Brake Pedal Spongy When Depressed
- High Pitched Squeal During Braking
- High Pitched Squeal During Driving — Goes Away During Braking
- Vehicle Pulls to One Side During Braking
- Pulsations or Jerky Braking
Brake Pedal Goes to Floor When Depressed
| Possible Cause | Checks | Procedure |
|---|---|---|
| Brake fluid is low | Check brake reservoir level and fill if necessary. | N/A |
| Brake Master Cylinder bad | Check for signs of leakage from the master cylinder in the engine compartment next to the firewall and inside the driver's footwell. If leakage is found or all other causes have been eliminated, replace the master cylinder. | BRAKE-06 |
| Air in the brake system | Bleed brakes. | BRAKE-01 |
Brake Pedal Feels Spongy During Braking
| Possible Cause | Checks | Procedure |
|---|---|---|
| Master Cylinder mounting bolts loose | Check bolts and tighten if necessary. | N/A |
| Brake Master Cylinder bad | Check for signs of leakage from the master cylinder in the engine compartment next to the firewall and inside the driver's footwell. Replace if leaking or after other causes are eliminated. | BRAKE-06 |
| Air in the brake system | Bleed brakes. | BRAKE-01 |
High Pitched Squeal During Braking
| Possible Cause | Checks | Procedure |
|---|---|---|
| Brake pads worn | Replace brake pads immediately. | BRAKE-02 |
High Pitched Squeal During Driving — Goes Away During Braking
| Possible Cause | Checks | Procedure |
|---|---|---|
| Excessive Brake Dust | Brake dust that migrates between the back of the brake pad and the caliper piston causes vibration (squealing) during driving. When the brake pedal is depressed, the piston clamps the pad and stops the vibration. Several remedies: (1) Anti-squeal pads — most pad sets include these; they can also be obtained separately at auto parts stores. (2) Brake pad grease — applying grease to the back of the pad stops vibration; bearing grease works as well as dedicated brake pad grease. (3) Adhesive — adhering the pad to the caliper piston with an appropriate automotive adhesive (such as 3M Vinyl and Trim Adhesive) can stop squeal when other methods fail. (4) Pad selection — some pads produce significantly more dust than others; switching to a lower-dust pad may eliminate the problem. | BRAKE-02 |
Vehicle Pulls to One Side During Braking
| Possible Cause | Checks | Procedure |
|---|---|---|
| Wrong tire pressure | Check that all tires have the correct pressure. | N/A |
| Suspension out of alignment | Have alignment checked and corrected if necessary. | N/A |
| Crimped or pinched brake line | Inspect all brake lines. | N/A |
| Loose or malfunctioning brake caliper | Raise wheels off the ground, apply brakes, and attempt to turn wheels by hand. If a caliper is not working, try bleeding the brake for that wheel to see if the brake line is clogged. If the line is not clogged, the caliper is probably bad and needs to be rebuilt or replaced. | N/A |
Pulsations or Jerky Braking
| Possible Cause | Checks | Procedure |
|---|---|---|
| Brake rotor lateral runout excessive | Check rotor lateral runout against specifications. | BRAKE-04 |
| Brake pads contaminated | Brake pads contaminated with brake fluid or oil can cause jerky brake operation. Remove the brake pads, inspect, and replace if necessary. | BRAKE-02 |
Tags:brakesbrake pedalbrake squealbrake pullbrake pulsationmaster cylinder