Symptom Chart - NVH
NVH symptoms should be identified using the diagnostic tools that are available. For a list of these tools, an explanation of their uses and a glossary of common terms, REFER to: Noise, Vibration and Harshness (NVH) . Since it is possible any one of multiple systems may be the cause of a symptom, it may be necessary to use a process of elimination type of diagnostic approach to pinpoint the responsible system. If this is not the causal system for the symptom, REFER to: Noise, Vibration and Harshness (NVH) for the next likely system and continue diagnosis.
| Condition | Possible Sources | Action |
|---|---|---|
| Steering system cold start noise | Blockage in the power steering fluid reservoir filter screen or return ports caused by power steering fluid contamination |
NOTE:
Some noise during an extremely cold start (-12.2 °C [-10 °F]) is normal and should improve as the steering system warms up (usually within 60 seconds).
NOTE:
It may be necessary to remove the power steering fluid reservoir to flush contamination trapped in the reservoir filter/screen or to remove blockage in the return ports. CHECK the power steering fluid reservoir filter/screen or return ports for contaminants or blockage. FLUSH the power steering system as necessary. Refer to: Power Steering System Flushing . |
| Air in the steering hydraulic system (aerated fluid) | CHECK for leaks in the system. REFER to Power Steering Fluid Leak Test . PURGE the air from the system. Refer to: Power Steering System Purging . | |
| Steering grunt or shudder - occurs when turning into or out of a turn at low speeds (temperature sensitive) | Air in the steering hydraulic system (aerated fluid) | CHECK for leaks in the system. REFER to P Power Steering Fluid Leak Test . PURGE the air from the system. Refer to: Power Steering System Purging . |
| Steering gear or power steering hoses | GO to Steering Gear Grunt/Shudder Test . | |
| Steering system clonk - hydraulic knocking sound | Air in the steering hydraulic system (aerated fluid) |
NOTE:
Some amount of clonk noise is considered acceptable. If in doubt of the acceptability, compare to another vehicle. CHECK for leaks in the system. REFER to Power Steering Fluid Leak Test . PURGE the air from the system. Refer to: Power Steering System Purging . |
| Power steering pump moan - loud humming noise occurs when the steering wheel is rotated to the stop position. Produces a 120-600 Hz frequency that changes with rpm | Low fluid and/or air in the steering hydraulic system (aerated fluid) | CHECK for leaks in the system. REFER to Power Steering Fluid Leak Test . PURGE the air from the system. Refer to: Power Steering System Purging . If a pump moan still exists, INSTALL a new power steering pump. REFER to: Power Steering Pump - 3.5L EcoBoost (235kW/320PS)/3.7L Duratec (199kW/270PS) . or REFER to: Power Steering Pump - 3.2L Duratorq-TDCi (148kW/200PS) - Puma . |
| Blockage in the power steering fluid reservoir filter/ screen or return ports caused by power steering fluid contamination |
NOTE:
It may be necessary to remove the power steering fluid reservoir to flush contamination trapped in the reservoir filter/screen or to remove blockage in the return ports. CHECK the power steering fluid reservoir filter/screen or return ports for contaminants or blockage. FLUSH the power steering system as necessary. Refer to: Power Steering System Flushing . |
|
| Power steering line/hose grounded to chassis | INSPECT the power steering lines/hoses. REPAIR as necessary. | |
| Power steering pump brackets loose or misaligned | CHECK bolts, brackets and bracket alignment. TIGHTEN bolts to specification. REPAIR or INSTALL new brackets as necessary. Refer to: Power Steering Pump - 3.5L EcoBoost (235kW/320PS)/3.7L Duratec (199kW/270PS) . or REFER to: Power Steering Pump - 3.2L Duratorq-TDCi (148kW/200PS) - Puma . | |
| Steering gear isolators | INSPECT the isolators for wear or damage. REPAIR as necessary. | |
| Steering gear clunk - occurs only while cornering over a bump (can be temperature sensitive) | Steering gear | INSPECT the steering gear for loose mounting bolts. TIGHTEN to specification as necessary. Refer to: Steering Gear . |
| Feedback (rattle, chuckle or knocking noise in the steering gear) - roughness is felt in the steering wheel when the vehicle is driven over rough surfaces | Steering column shaft/ coupling joints damaged or worn | INSTALL a new steering column shaft. Refer to: Steering Column . |
| Loose, damaged or worn tie rod ends | INSPECT and INSTALL new tie-rod ends as necessary. GO to Steering Linkage Test . | |
| Steering gear insulators or mounting bolts loose or damaged | TIGHTEN the bolts to specification or INSTALL new bolts as necessary. Refer to: Steering Gear . | |
| Steering column shaft/ coupling bolts are loose | TIGHTEN the bolts to specification. Refer to: Steering Column . | |
| Steering column damaged or worn | REPAIR or INSTALL a new steering column as necessary. Refer to: Steering Column . | |
| Power steering hiss or whistle | Steering column shaft/ coupling-to-steering gear is binding or misaligned | REPAIR or INSTALL a new steering column shaft as necessary. Refer to: Steering Column . |
| Grounded or loose steering column boot at the dash panel | REPAIR as necessary. | |
| Damaged or worn steering gear input shaft and valve | REPAIR or INSTALL a new steering gear as necessary. Refer to: Steering Gear . | |
| Restricted power steering lines/hoses | GO to Pinpoint Test A | |
| Steering column rattle | Loose bolts or attaching brackets | TIGHTEN the bolts to specification. |
| Loose, worn or insufficiently lubricated column bearings | LUBRICATE bearings or INSTALL new steering column bearings or steering column as necessary. Refer to: Steering Column . | |
| Steering column shaft/ coupling compressed or extended | INSPECT the rubber spider coupling for damage. INSTALL a new intermediate/flexible shaft as necessary. | |
| Steering gear squeak | Incorrect power steering fluid in system | If incorrect power steering fluid is suspected, FLUSH the power steering system. Refer to: Power Steering System Flushing . If noise persists after system flush, INSTALL a new steering gear. REFER to: Steering Gear . |
| Steering gear rotary seal |
NOTE:
Use the chassis ears to verify that the steering gear is the source of the noise. It may be necessary to replicate the customer operating conditions (fluid temperature, turning rate of steering wheel) to get the squeak to reoccur. INSTALL a new steering gear as necessary. Refer to: Steering Gear . |
|
| Stone shield (if equipped) | MAKE SURE that the stone shield is correctly installed and that it is not making contact with the steering shaft. REPOSITION stone shield or INSTALL a new stone shield as necessary. | |
| Steering column squeak, cracks or grinds | Loose or misaligned steering column shrouds | TIGHTEN or ALIGN the steering column shrouds. |
| Steering wheel rubbing against steering column shrouds | REPOSITION the steering column shrouds. | |
| Steering column ticking or creaking noise | Steering column lower bearing | VERIFY that the noise is coming from the lower bearing and REPLACE steering column as necessary. Refer to: Steering Column . |
| Power steering pump noisy | Blockage in the power steering fluid reservoir filter/ screen or return ports caused by power steering fluid contamination |
NOTE:
It may be necessary to remove the power steering fluid reservoir to flush contamination trapped in the reservoir filter/screen or to remove blockage in the return ports. CHECK the power steering fluid reservoir filter/screen or return ports for contaminants or blockage. FLUSH the power steering system as necessary. Refer to: Power Steering System Flushing . |
| Power steering pump | INSTALL a new power steering pump as necessary. Refer to: Power Steering Pump - 3.5L EcoBoost (235kW/320PS)/3.7L Duratec (199kW/270PS) . or REFER to: Power Steering Pump - 3.2L Duratorq-TDCi (148kW/200PS) - Puma . | |
| Power steering pump noise (steering wheel turned fully to stop/lock) | Power steering fluid flow into the bypass valve of the pump valve housing, with fluid temperature below 54 °C (130 °F) | Acceptable condition. |
| Power steering pump whine noise | Aerated fluid | CHECK for a leak in the system. REFER to Power Steering Fluid Leak Test . PURGE the air from the system. Refer to: Power Steering System Purging . |
| Blockage in the power steering fluid reservoir filter/ screen or return ports caused by power steering fluid contamination |
NOTE:
It may be necessary to remove the power steering fluid reservoir to flush contamination trapped in the reservoir filter/screen or to remove blockage in the return ports. CHECK the power steering fluid reservoir filter/screen or return ports for contaminants or blockage. FLUSH the power steering system as necessary. Refer to: Power Steering System Flushing . |
|
| Damaged power steering pump | INSTALL a new power steering pump as necessary. Refer to: Power Steering Pump - 3.5L EcoBoost (235kW/320PS)/3.7L Duratec (199kW/270PS) . or REFER to: Power Steering Pump - 3.2L Duratorq-TDCi (148kW/200PS) - Puma . | |
| High speed shake or shimmy - occurs at high speeds | Worn or damaged steering linkage components | GO to Steering Linkage Test . |