50 General (Fault tracing): General Information
- Make
- Volvo
- Model
- S90 Factory Service Manual
- Year
- 1997–1998
- Section
- 50 General › General Information › Fault tracing
5 BrakesFault tracing
Fault tracing
Brakes - general
| CAUSE | ACTION |
|---|---|
| Excessive brake travel | |
| Air in hydraulic system. | Bleed system. |
| Too little brake fluid in system. | Check for leakage. Bleed system. |
| Brake pedal reaches floor | |
| Too little brake fluid in system. | Check for leakage. Bleed system. |
| Air in hydraulic system. | Bleed system. |
| Leakage from hydraulic system. | Locate and repair leakage. Bleed system |
| Faulty master cylinder. | Recondition cylinder. Replace as required. |
| Poor braking action | |
| Moisture on brake pads and discs. | Brake repeatedly to correct fault. |
| Grease or oil on brake pads. | Replace pads. Check adjoining seals. |
| Faulty or leaking brake servo. | Check servo. Replace as required. |
| Leakage from brake servo vacuum hose connections. | Check and replace components as required. |
| Car pulls to one side when braking | |
| Grease or oil on a brake pad. | Replace pad. Check seals. |
| Faulty brake caliper. | Recondition or replace caliper. |
| Excessive play in wheel bearings or incorrect wheel alignment. | Check suspension and steering. |
| Uneven tyre pressure. | Adjust pressure. |
| Uneven tyre wear. | Replace tyres; check front wheel alignment. |
| Faulty suspension and steering adjustment. | Adjust suspension and steering. |
| New brake pads. | Drive until pads are bedded in. |
| Brakes snatching | |
| Moisture on brake pads and discs. | Brake repeatedly to correct fault. |
| Excessive wheel bearing play. | Adjust bearings. |
| Worn brake pads. | Replace pads. |
| Pulsation in pedal due to excessive variation in disc thickness. | Recondition or replace disc. |
| Loose brake caliper. | Tighten loose component. |
| Brake squeal | |
| Atmospheric influence. | Brake repeatedly to eliminate squeal. |
| 'Glazed' pad surface. | Brake hard several times. |
| Worn brake pads. | Replace pads. |
| Pads vibrating in brake caliper. | Install shim if available as spare part. |
| Anti-squeal shim missing or not lubricated. | Lubricate pad backing plate and shim with grease, P/N 1 161 325-4. |
| Brakes remain on | |
| Brake piston seizing in caliper. | Recondition or replace caliper. |
| Brake pads sticking in brake caliper. | Clean caliper and replace pads. |
| Guide pin seizing in brake caliper. | Clean or replace caliper. |
| Brake cylinder pushrod incorrectly adjusted. | Adjust pushrod. |
| Equalising port in master cylinder blocked. | Recondition master cylinder. |
| Deformed brake pipe. | Replace pipe. |
| Brake hose blocked. | Replace hose. |
| Worn fluid seal in caliper. | Recondition or replace caliper. |
| Parking brake incorrectly adjusted. | Adjust brake. |
| Cable sticking. | Replace cable. |
Fault tracing, brake resonance - Vibrations in steering wheel/brake pedal when braking
| Resonance when driving? (not when braking) | yes | Check wheel balance Check tyres Check suspension/steering | ||
| no | ||||
| no | Resonance when braking? | |||
| Job completed | yes | |||
| Remove front brake disc/pads | ||||
| < 0.03mm | Check hub runout Use tool 999 5418 | > 0.03 mm | Replace hub | |
| Is hub marked? Is installation position correct? | yes | |||
| no | ||||
Mark hub for mounting 180° from highest point. Use tool 999 5418 | Clean/install new brake discs Install hubs and discs in correct positions | |||
| Check lateral runout of disc (see General) | < 0.06 mm | |||
| < or = 0.06 mm | ||||
| Install new brake pads | ||||
| Torque wheel nuts diagonally (see Brakes) | ||||
| Test drive | ||||
| Resonance still present? | no | Job completed | ||
| yes | ||||
| Check rear brakes |
Parts & tools for this job For 1997 Volvo S90
- PARTBrake padsSearch: Volvo S90 1997 brake pads
- TOOLBrake bleeder kitSearch: one man brake bleeder kit
- FLUIDBrake fluidSearch: brake fluid
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