34 90 ...Troubleshooting the brake system

TROUBLE SHOOTING OF BRAKE SYSTEM

Fault	Cause	Remedy
Brakes pull to one side	a) Tyre pressure incorrect b) Unevenly worn tire treads c) Oil on pads/liners d) Wrong type of pads/liners e) Dirty floating caliper recesses f) Guide bolts dirty or damaged g) Rear wheel alignment adjusted incorrectly h) Corrosion in floating calipers or wheel cylinders i) No shock absorber action k) Pad of one caliper worn l) Pad glazed	a) Correct tire pressure b) Change or replace tires c) Replace brake linings, check for causes d) Replace brake linings, check for causes e) Remove and install/clean floating calipers f) Replace guide bolts g) Check wheel alignment h) Remove and install, repair or replace floating calipers or wheel cylinders i) Check shock absorber, replacing if necessary k) Replace brake linings, Check floating caliper l) Replace brake linings, Check floating caliper
Brakes excessively hot while driving	Vent bore in master cylinder clogged No play between push rod and master cylinder piston Swollen rubber parts due to use of wrong brake fluid Vent bore in expansion tank clogged Corroded floating calipers Cross spring broken Handbrake lever not released fully	Overhaul master brake cylinder, replacing if necessary Adjust push rod (in older cars) Overhaul master brake cylinder, replacing if necessary Clean expansion tank Remove and install, repair or replace floating calipers Replace cross spring Check handbrake and handbrake cables, repair if necessary
Poor braking effect in spite of great force on pedal Brake-pedal travel normal	Brake pads oil-splattered or burnt; wrong type of brake pads	Replace brake linings
Poor braking effect in spite of great force on pedal Brake-pedal travel short	Brake booster malfunctions - engine vacuum	Check brake booster system Check engine (valves, cylinder head gasket etc.)
Poor braking effect in spite of great force on pedal Brake-pedal travel long	One brake circuit failed due to leaks or damage	Leakage test of brake system
Brake-pedal motion too soft and spongy	Air in braking system Insufficient brake fluid in expansion tank - refer to a) Overheated brake fluid - vapour lock due to excessive water content in brake fluid or excessive brake loads	Top up or change brake fluid Bleed brakes Top up or change brake fluid Bleed brakes Top up or change brake fluid Bleed brakes
Brake-pedal travel is excessive even though brakes have been bled and adjusted	Primary cup in master cylinder damaged Separating cups on floating piston of tandem-brake master cylinder leak Leak in braking system	Overhaul or replace brake master cylinder Overhaul or replace brake master cylinder Leakage test of brake system
Uneven pad wear	Wrong type of pads/liners Dirty fist caliper recesses, damaged caps Corrosion in floating calipers or wheel cylinders Swollen rubber ring for piston control	Replace brake linings Remove and install, repair or replace floating calipers or wheel cylinders Remove and install, repair or replace floating calipers or wheel cylinders Remove and install, repair or replace floating calipers or wheel cylinders
Brake pads worn at angle	Wheel-bearing play excessive Brake disc not aligned with fist caliper Corrosion in floating calipers or wheel cylinders Angular brake-disc wear Pads worn to less than minimum thickness Spring force insufficient Guide bolts damaged	Replace wheel bearings Check floating caliper installation Remove and install, repair or replace floating calipers or wheel cylinders Grind or replace brake discs Replace brake linings Replace spring Replace guide bolts
Seized brake pads, pad does not move off brake disc	Dirty fist caliper recesses, damaged caps Corrosion in floating calipers Vent bore in master cylinder clogged	Remove and install, repair or replace floating calipers Remove and install, repair or replace floating calipers Overhaul or replace brake master cylinder
Brakes squeal or rattle	a) Wrong type of pads/liners b) Dirty floating caliper recesses c) Spring force insufficient d) Brake disc not aligned with fist caliper e) Brake-disc runout f) Excessive thickness deviation within braking surface g) Brake drums eccentric h) Knocking brake drums i) Dirt and dust in brake drums k) Liner wear excessive or onesided l) Rust edges on brake discs m) Pad loose n) Wheel-bearing play excessive	a) Replace brake linings b) Remove and install/clean floating calipers c) Replace spring d) Check floating caliper installation e) Check brake discs for runout, replacing if necessary f) Measure brake disc thickness Grind or replace disks g) Grind or replace brake drums h) Grind or replace brake drums i) Clean and check brake drums k) Replace brake shoes l) Grind or replace brake discs m) Replace brake linings n) Replace wheel bearings
Brake-pedal dead travel excessive	Wheel-bearing play excessive Brake disc not aligned with fist caliper Brake-disc runout Excessive thickness deviation within braking surface Brake system leaky Air in braking system Wrong type of pads/liners Automatic slack control of brake shoes does not function	Replace wheel bearings Check floating caliper installation Check brake discs for runout, replacing if necessary Measure brake disc thickness Grind or replace discs Leakage test of brake system Bleed brakes Replace brake linings or Replace brake shoes Remove and install brake shoes, Repair adjustment unit
Jammed piston in brake caliper	Dirty fist caliper recesses, damaged caps Brake disc not aligned with fist caliper Corrosion on pistons in floating calipers or wheel cylinders	Remove and install, repair or replace floating calipers Check floating caliper installation Remove and install, repair or replace floating caliper or wheel cylinder
Pulsating effect on brake pedal	Wheel-bearing play excessive Brake disc not aligned with fist caliper Brake-disc runout Excessive thickness deviation within braking surface	Replace wheel bearings Check floating caliper installation Check brake discs for runout, replacing if necessary Measure brake disc thickness Grind or replace discs
Handbrake effect insufficient	Brake shoes oil-splattered Excessive dead travel between brake shoes and brake drums Excessive dead travel in cables Cables adjusted incorrectly Corroded transmitting elements	Replace brake linings, determine cause Adjusting handbrake Adjusting handbrake Adjusting handbrake Remove and install handbrake and expander locks Check Bowden cables, replacing if necessary