Toyota
Ford Kuga
 Service Manual
Noise, Vibration and Harshness
Symptom Chart

Power Steering Moan Noise

Test Condition

Listen for steering moan noise with the vehicle parked, transmission in neutral and all windows closed in the following test conditions.

1. Engine speed at idle with no steering action.

2. Engine speed at idle with slow 90 degrees per second turning of the steering wheel.

3. Engine speed at 1250 +/- 50 rpm with no steering action.

4. Engine speed at 1250 +/- 50 rpm with slow 90 degrees per second turning of the steering wheel.

Symptom Possible Sources Action
Power steering system moan noise - A continuous low pitched humming noise occurs when the steering wheel is turned and the steering system is loaded. Noise frequency changes with engine rpm changes. Particularly annoying at lower engine speed. Power steering lines.
  • CHECK the routing of the power steering lines.
  • CHECK the power steering line clamps are secure.
  • CHECK the power steering lines for clearance from the vehicle body, front axle crossmember and steering gear.
Incorrect power steering fluid. FLUSH the power steering system.

REFER to: Power Steering System Flushing (211-00 Steering System - General Information, General Procedures).

Power steering pump. Pressure pulses from the power steering pump. Certain amount of noise level acceptable, not a safety critical item.

Power Steering Whine Noise

Test Condition

Listen for steering whine noise with the vehicle parked, transmission in neutral and all windows closed in the following test conditions.

1. Engine speed at 1800 +/- 50 rpm with no steering action.

2. Engine speed at 1800 +/- 50 rpm with slow 90 degrees turning of the steering wheel.

3. Engine speed at 3000 +/- 50 rpm with no steering action.

4. Engine speed at 3000 +/- 50 rpm with slow 90 degrees turning of the steering wheel.

Symptom Possible Sources Action
Power steering system whine noise - a high pitched buzzing sound like an electric motor or drill. Whine occurs at the higher engine rpm, 1500 - 5000 rpm, frequency does not change if system is loaded or not loaded. Power steering fluid aeration. BLEED the power steering system.

REFER to: Power Steering System Vacuum Bleeding (211- 00 Steering System - General Information, General Procedures).

Incorrect power steering fluid. FLUSH the power steering system.

REFER to: Power Steering System Flushing (211-00 Steering System - General Information, General Procedures).

Overheated power steering fluid. FLUSH the power steering system.

REFER to: Power Steering System Flushing (211-00 Steering System - General Information, General Procedures).

Hydraulic operating condition of the power steering pump. Certain amount of noise level acceptable, not a safety critical item.

Power Steering Hiss Noise

Test Condition

Listen for steering hiss noise with the vehicle parked, transmission in neutral and all windows closed in the following test conditions.

Symptom Possible Sources Action
NOTE: Engine speed at idle turning the steering wheel slowly lock to lock.

Power steering system hiss noise - a high frequency, continuous rush or swish noise like escaping air from a balloon. Hiss occurs while turning between the steering lock stops, all steering angles. Noise does not change with engine rpm and is worse at high operating temperatures.

Floor seal. CHECK the installation and potential damage of the floor seal.
Power steering gear valve design. Certain amount of noise level acceptable, not a safety critical item.
Power steering system hydraulic design. Certain amount of noise level acceptable, not a safety critical item.
NOTE: Engine speed at idle holding the steering wheel against a steering lock for three seconds. Do not hold for more than five seconds.

Power steering system hiss noise - a continuous noise like escaping air occurs while holding the steering against a steering lock stop.

Power steering pump pressure relief valve. Certain amount of noise level acceptable, not a safety critical item.

Power Steering Lock Stop Impact Knock Noise

Test Condition

Listen for steering knock noise with the engine speed at idle in the following test conditions (noise also apparent with engine off).

1. Turn the steering wheel to the left-hand and right-hand steering locks and listen for the impact noise.

Symptom Possible Sources Action
Power steering system knock noise - a heavy loud sound like a knock on a door that occurs in parking condition when hitting the lock stop. Power steering gear mechanical noise, metal to metal at end of steering travel. Certain amount of noise level acceptable, not a safety critical item.

Power Steering Mechanical Knock Noise (PAS off)

Test Condition

Listen for steering knock noise with the engine off in the following test conditions (no power assist).

1. Turn the steering wheel 90 degrees to the right, hold and then quickly release.

2. Turn the steering wheel 90 degrees to the left, hold and then quickly release.

Symptom Possible Sources Action
Power steering system knock noise - a heavy loud repeating sound like a knock on a door that occurs in several driving and steering conditions. Power steering system knock noise - a damped, metallic knock noise which only occurs at steering condition with engine off (very high efforts). Certain amount of noise level acceptable, not a safety critical item.
Tolerances in the steering gear components. Certain amount of noise level acceptable, not a safety critical item.

Power Steering Mechanical Knock Noise (PAS on)

Test Condition

Listen for steering knock noise with the engine speed at idle in the following test conditions (power assist).

1. Turn the steering wheel to a steering lock and return to center quickly.

2. Turn the steering wheel 90 degrees to the left and then 90 degrees to the right quickly.

Symptom Possible Sources Action
Power steering system knock noise - clear knock noise from steering gear linkage area. Worn tie-rod ball joints (inner and outer ball joints). REFER to Steering System.

REFER to: Steering System (211- 00 Steering System - General Information, Diagnosis and Testing).

Power Steering Hammer Knock (Hydraulic) Noise

Test Condition

Listen for steering knock noise with the engine speed at idle in the following test conditions (for vehicles with hydraulic power assisted steering only, not electro-hydraulic power steering).

1. Turn the steering wheel to a steering lock position and return quickly.

Symptom Possible Sources Action
Power steering system knock noise - loud, metallic sound if hitting the suspension crossmember with a hammer (sounds like metallic noise but is created by pressure impulse in gear and return line). Hydraulic noise created by pressure impulses. Certain amount of noise level acceptable, not a safety critical item.

Power Steering Hydraulic Knock/Clonk Noise

Test Condition

Listen for steering knock/clonk noise in the following test conditions with the windows closed.

1. Drive over cobbled roads at low speed 10-30 km/h (6-20 mph) with and without turning.

2. Drive over straight tar strips road rails or 25 mm tall harshness strips at low speed 10-30 km/h (6-20 mph) both driving straight and with moderate turning.

Symptom Possible Sources Action
Power steering system knock/ clonk noise - sounds almost identical to column knock that occurs when driving and cornering over cobbled stones or rough roads. Noise may appear to emanate from a location closer to the floor than that for column knock (Sounds like metallic noise but is created by pressure impulse in gear and return line - similar to a sound like quickly turning off a water tap). Power steering return lines Certain amount of noise level acceptable, not a safety critical item.
High power assist gain of power steering gear valve (steering gear design - no quality issue). Certain amount of noise level acceptable, not a safety critical item.
High power steering pump flow rate (by design). Certain amount of noise level acceptable, not a safety critical item.

Power Steering Column Knock Noise

Test Condition

Listen for steering knock noise in the following test conditions with windows closed.

1. Drive over cobbled stones at low speed 16-40 km/h (10-25 mph) with and without steering input carefully listening for knock sounds.

2. Drive over straight tar strips, road rails or 25 mm tall harshness strips at low speed 16-40 km/h (10-25 mph) both driving straight and with moderate cornering.

Symptom Possible Sources Action
Power steering system column knock noise - a loose sounding rattle or vibration coming from the column. Noticeable by hearing and touch. Steering column or steering column shaft. CHECK the steering column retaining bolts and attachments to the steering column and secure if necessary.
Check steering column and intermediate shaft for free play or loose components.

REFER to: Steering System (211- 00 Steering System - General Information, Diagnosis and Testing).

Power Steering Toc-Toc Noise

Test Condition

Listen for steering toc-toc noise with the engine speed at idle and the vehicle parked, automatic transmission in "P" (PARK) or manual transmission in neutral and the windows closed.

1. Turn the steering wheel from left to right abruptly changing direction.

2. Drive the vehicle for low speed parking manoeuvres constantly changing steering direction.

Symptom Possible Sources Action
Power steering system toc-toc noise - a metallic noise created when changing direction of steering wheel rotation during parking manoeuvre or at standstill. Steering gear (design tolerance in steering rack). Certain amount of noise level acceptable, not a safety critical item.

Power Steering Grinding Noise

Test Condition

Listen for steering grinding noise with the engine speed at idle and the vehicle parked, automatic transmission in "P" (PARK) or manual transmission in neutral and the windows closed.

1. Slowly turn the steering wheel from lock to lock.

2. Tilt and extend the steering column in various positions and slowly turn the steering wheel from lock to lock.

Symptom Possible Sources Action
Power steering system grinding noise - an abrasive noise (like sand paper rubbing against wood) occurs between moving components such as steering wheel and the steering column shroud. Steering wheel to shroud interference. Certain amount of noise level acceptable, not a safety critical item.
Steering column bearing. Certain amount of noise level acceptable, not a safety critical item.
Foreign material in contact with the steering column shaft. CHECK if floor covering is obstructing the steering gear pinion.
CHECK the installation of the floor seal.
Clockspring. CHECK the clockspring and secure if necessary.

REFER to: Clockspring (501-20 Supplemental Restraint System, Removal and Installation).

Power Steering Zip Noise

Symptom Possible Sources Action
Power steering system zip noise - occurs when hydraulic fluid does not flow freely through the power steering pump supply hose from steering fluid reservoir to power steering pump causing cavitation at the pump. Zip is primarily a cold weather start-up phenomenon (below -10C). High viscosity of power steering fluid at low temperature. Certain amount of noise level acceptable, not a safety critical item.
Aeration of the power steering fluid. BLEED the power steering system.

REFER to: Power Steering System Vacuum Bleeding (211- 00 Steering System - General Information, General Procedures).

Driveline Noise and Vibration

Symptom Possible Sources Action
Shake and vibration while driving
  • Wheel end vibration.
  • Engine/transmission.
GO to Pinpoint Test A.
Tip-in moan
  • Air cleaner.
  • Power assisted steering.
  • Powertrain.
  • Powertrain/drivetrain mounts
  • Exhaust system.
GO to Pinpoint Test B.
Idle boom/shake/vibration/ shudder
  • Cable(s)/hose(s).
  • Powertrain/drivetrain mounts
  • Exhaust system.
  • Belt/pulleys.
GO to Pinpoint Test C.

Suspension Noise and Vibration

Symptom Possible Sources Action
Wheel end vibration analysis
  • Suspension.
  • Wheel bearings.
GO to Pinpoint Test D.
Non-axle noise
  • Trim panels.
  • Air conditioning (A/C) system.
  • Accessories.
GO to Pinpoint Test E.
    More about «Noise, Vibration and Harshness»:

    Noise, Vibration and Harshness (NVH)

    Road Test

    Road Test Quick Checks

    Noise Diagnostic Procedure

    Road Conditions

    Power Steering Conditions

    Power Steering Operation Noise Check

    Symptom Chart

    Pinpoint Tests

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