Troubleshooting Ford F150
PROBABLE CAUSE |
CORRECTIVE ACTION |
No brakes — pedal travels to floor |
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1 Low fluid level
2 Air in system |
1 and 2 Low fluid level and air in the system are symptoms of another problem a leak somewhere in the hydraulic system. Locate and repair the leak |
| 3 Defective seals in master cylinder | 3 Replace master cylinder |
| 4 Fluid overheated and vaporized due to heavy braking | 4 Bleed hydraulic system (temporary fix). Replace brake fluid (proper fix) |
Brake pedal slowly travels to floor under braking or at a stop |
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| 1 Defective seals in master cylinder | 1 Replace master cylinder |
| 2 Leak in a hose, line, caliper or wheel cylinder | 2 Locate and repair leak |
| 3 Air in hydraulic system | 3 Bleed the system, inspect system for a leak |
Brake pedal feels spongy when depressed |
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1 Air in hydraulic system
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1 Bleed the system, inspect system for a leak |
| 2 Master cylinder or power booster loose | 2 Tighten fasteners |
| 3 Brake fluid overheated (beginning to boil) | 3 Bleed the system (temporary fix). Replace the brake fluid (proper fix) |
| 4 Deteriorated brake hoses (ballooning under pressure) | 4 Inspect hoses, replace as necessary (it’s a good idea to replace all of them if one hose shows signs of deterioration) |
Brake pedal feels hard when depressed and/or excessive effort required to stop vehicle |
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1 Power booster faulty
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1 Replace booster |
| 2 Engine not producing sufficient vacuum, or hose to booster clogged, | 2 Check vacuum to booster with a vacuum gauge. Replace hose if cracked collapsed or cracked or clogged, repair engine if vacuum is extremely low |
| 3 Brake linings contaminated by grease or brake fluid | 3 Locate and repair source of contamination, replace brake pads or shoes |
| 4 Brake linings glazed | 4 Replace brake pads or shoes, check discs and drums for glazing, service as necessary |
| 5 Caliper piston(s) or wheel cylinder(s) binding or frozen | 5 Replace calipers or wheel cylinders |
| 6 Brakes wet | 6 Apply pedal to boil-off water (this should only be a momentary problem) |
| 7 Kinked, clogged or internally split brake hose or line | 7 Inspect lines and hoses, replace as necessary |
Excessive brake pedal travel (but will pump up) |
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1 Drum brakes out of adjustment
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1 Adjust brakes |
| 2 Air in hydraulic system | 2 Bleed system, inspect system for a leak |
Excessive brake pedal travel (but will not pump up) |
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| 1 Master cylinder pushrod misadjusted | 1 Adjust pushrod |
| 2 Master cylinder seals defective | 2 Replace master cylinder |
| 3 Brake linings worn out | 3 Inspect brakes, replace pads and/or shoes |
| 4 Hydraulic system leak | 4 Locate and repair leak |
Brake pedal doesn’t return |
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1 Brake pedal binding
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1 Inspect pivot bushing and pushrod, repair or lubricate |
| 2 Defective master cylinder | 2 Replace master cylinder |
Brake pedal pulsates during brake application |
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| 1 Brake drums out-of-round | 1 Have drums machined by an automotive machine shop |
| 2 Excessive brake disc runout or disc surfaces out-of-parallel | 2 Have discs machined by an automotive machine shop |
| 3 Loose or worn wheel bearings | 3 Adjust or replace wheel bearings |
| 4 Loose lug nuts | 4 Tighten lug nuts |
Brakes slow to release |
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1 Malfunctioning power booster
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1 Replace booster |
| 2 Pedal linkage binding | 2 Inspect pedal pivot bushing and pushrod, repair/lubricate |
| 3 Malfunctioning proportioning valve | 3 Replace proportioning valve |
| 4 Sticking caliper or wheel cylinder | 4 Repair or replace calipers or wheel cylinders |
| 5 Kinked or internally split brake hose | 5 Locate and replace faulty brake hose |
Brakes grab (one or more wheels) |
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| 1 Grease or brake fluid on brake lining | 1 Locate and repair cause of contamination, replace lining |
| 2 Brake lining glazed | 2 Replace lining, deglaze disc or drum |
Vehicle pulls to one side during braking |
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| 1 Grease or brake fluid on brake lining | 1 Locate and repair cause of contamination, replace lining |
| 2 Brake lining glazed | 2 Deglaze or replace lining, deglaze disc or drum |
| 3 Restricted brake line or hose | 3 Repair line or replace hose |
| 4 Tire pressures incorrect | 4 Adjust tire pressures |
| 5 Caliper or wheel cylinder sticking | 5 Repair or replace calipers or wheel cylinders |
| 6 Wheels out of alignment | 6 Have wheels aligned |
| 7 Weak suspension spring | 7 Replace springs |
| 8 Weak or broken shock absorber | 8 Replace shock absorbers |
Brakes drag (indicated by sluggish engine performance or wheels being very hot after driving) |
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| 1 Brake pedal pushrod incorrectly adjusted | 1 Adjust pushrod |
| 2 Master cylinder pushrod (between booster and master cylinder) | 2 Adjust pushrod incorrectly adjusted |
| 3 Obstructed compensating port in master cylinder | 3 Replace master cylinder |
| 4 Master cylinder piston seized in bore | 4 Replace master cylinder |
| 5 Contaminated fluid causing swollen seals throughout system | 5 Flush system, replace all hydraulic components |
| 6 Clogged brake lines or internally split brake hose(s) | 6 Flush hydraulic system, replace defective hose(s) |
| 7 Sticking caliper(s) or wheel cylinder(s) | 7 Replace calipers or wheel cylinders |
| 8 Parking brake not releasing | 8 Inspect parking brake linkage and parking brake mechanism, repair as required |
| 9 Improper shoe-to-drum clearance | 9 Adjust brake shoes |
| 10 Faulty proportioning valve | 10 Replace proportioning valve |
Brakes fade (due to excessive heat) |
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| 1 Brake linings excessively worn or glazed | 1 Deglaze or replace brake pads and/or shoes |
| 2 Excessive use of brakes | 2 Downshift into a lower gear, maintain a constant slower speed (going down hills) |
| 3 Vehicle overloaded | 3 Reduce load |
Brakes fade (due to excessive heat) (continued) |
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4 Brake drums or discs worn too thin
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4 Measure drum diameter and disc thickness, replace drums or discs as required |
| 5 Contaminated brake fluid | 5 Flush system, replace fluid |
| 6 Brakes drag | 6 Repair cause of dragging brakes |
| 7 Driver resting left foot on brake pedal | 7 Don’t ride the brakes |
Brakes noisy (high-pitched squeal) |
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| 1 Glazed lining | 1 Deglaze or replace lining |
| 2 Contaminated lining (brake fluid, grease, etc.) | 2 Repair source of contamination, replace linings |
| 3 Weak or broken brake shoe hold-down or return spring | 3 Replace springs |
| 4 Rivets securing lining to shoe or backing plate loose | 4 Replace shoes or pads |
| 5 Excessive dust buildup on brake linings | 5 Wash brakes off with brake system cleaner |
| 6 Brake drums worn too thin | 6 Measure diameter of drums, replace if necessary |
| 7 Wear indicator on disc brake pads contacting disc | 7 Replace brake pads |
| 8 Anti-squeal shims missing or installed improperly | 8 Install shims correctly |
Brakes noisy (scraping sound) |
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| 1 Brake pads or shoes worn out; rivets, backing plate or brake | 1 Replace linings, have discs and/or drums machined (or replace) shoe metal contacting disc or drum |
Brakes chatter |
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1 Worn brake lining
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1 Inspect brakes, replace shoes or pads as necessary |
| 2 Glazed or scored discs or drums | 2 Deglaze discs or drums with sandpaper (if glazing is severe, machining will be required) |
| 3 Drums or discs heat checked | 3 Check discs and/or drums for hard spots, heat checking, etc. Have discs/drums machined or replace them |
| 4 Disc runout or drum out-of-round excessive | 4 Measure disc runout and/or drum out-of-round, have discs or drums machined or replace them |
| 5 Loose or worn wheel bearings | 5 Adjust or replace wheel bearings |
| 6 Loose or bent brake backing plate (drum brakes) | 6 Tighten or replace backing plate |
| 7 Grooves worn in discs or drums | 7 Have discs or drums machined, if within limits (if not, replace them) |
| 8 Brake linings contaminated (brake fluid, grease, etc.) | 8 Locate and repair source of contamination, replace pads or shoes |
| 9 Excessive dust buildup on linings | 9 Wash brakes with brake system cleaner |
| 10 Surface finish on discs or drums too rough after machining | 10 Have discs or drums properly machined (especially on vehicles with sliding calipers) |
| 11 Brake pads or shoes glazed | 11 Deglaze or replace brake pads or shoes |
Brake pads or shoes click |
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1 Shoe support pads on brake backing plate grooved or
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1 Replace brake backing plate excessively worn |
| 2 Brake pads loose in caliper | 2 Loose pad retainers or anti-rattle clips |
| 3 Also see items listed under Brakes chatter | |
Brakes make groaning noise at end of stop |
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1 Brake pads and/or shoes worn out
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1 Replace pads and/or shoes |
| 2 Brake linings contaminated (brake fluid, grease, etc.) | 2 Locate and repair cause of contamination, replace brake pads or shoes |
Brakes fade (due to excessive heat) (continued) |
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3 Brake linings glazed
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3 Deglaze or replace brake pads or shoes |
| 4 Excessive dust buildup on linings | 4 Wash brakes with brake system cleaner |
| 5 Scored or heat-checked discs or drums | 5 Inspect discs/drums, have machined if within limits (if not, replace discs or drums) |
| 6 Broken or missing brake shoe attaching hardware | 6 Inspect drum brakes, replace missing hardware |
| Rear brakes lock up under light brake application | |
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1 Tire pressures too high
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1 Adjust tire pressures |
| 2 Tires excessively worn | 2 Replace tires |
| 3 Defective proportioning valve | 3 Replace proportioning valve |
Brake warning light on instrument panel comes on (or stays on) |
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| 1 Low fluid level in master cylinder reservoir (reservoirs with fluid level sensor) | 1 Add fluid, inspect system for leak, check the thickness of the brake pads and shoes |
| 2 Failure in one half of the hydraulic system | 2 Inspect hydraulic system for a leak |
| 3 Piston in pressure differential warning valve not centered | 3 Center piston by bleeding one circuit or the other (close bleeder valve as soon as the light goes out) |
| 4 Defective pressure differential valve or warning switch | 4 Replace valve or switch |
| 5 Air in the hydraulic system | 5 Bleed the system, check for leaks |
| 6 Brake pads worn out (vehicles with electric wear sensors — small probes that fit into the brake pads and ground out on the disc when the pads get thin) | 6 Replace brake pads (and sensors) |
Brakes do not self adjust |
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| Disc brakes | |
| 1 Defective caliper piston seals | 1 Replace calipers. Also, possible contaminated fluid causing soft or swollen seals (flush system and fill with new fluid if in doubt) |
| 2 Corroded caliper piston(s) | 2 Same as above |
| Drum brakes | |
| 1 Adjuster screw frozen | 1 Remove adjuster, disassemble, clean and lubricate with high-temperature grease |
| 2 Adjuster lever does not contact star wheel or is binding | 2 Inspect drum brakes, assemble correctly or clean or replace parts as required |
| 3 Adjusters mixed up (installed on wrong wheels after brake job) | 3 Reassemble correctly |
| 4 Adjuster cable broken or installed incorrectly (cable-type adjusters) 4 Install new cable or assemble correctly | |
Rapid brake lining wear |
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1 Driver resting left foot on brake pedal
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1 Don’t ride the brakes |
| 2 Surface finish on discs or drums too rough 3 Also see Brakes drag |
2 Have discs or drums properly machined |