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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. 1. Turn the steering wheel to a steering lock and return to center quickly.
2. 2. Turn the steering wheel 90 degrees to the left and then 90 degrees to the right
quickly.
Symptom
Power steering system knock
noise – clear knock noise from
steering gear linkage area.
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. 1. Turn the steering wheel to a steering lock position and return quickly.
Symptom
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).
Power Steering Hydraulic Knock/Clonk Noise
Test Condition
Listen for steering knock/clonk noise in the following test conditions with the windows
closed.
1. 1. Drive over cobbled roads at low speed 10-30 km/h (6-20 mph) with and without
turning.
2. 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.
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).
Possible Sources
Worn tie-rod ball
joints (inner and
outer ball joints).
Symptom
http://vnx.su
Action
REFER to Steering System.
REFER to:
Steering System
Steering System - General
Information, Diagnosis and Testing).
Possible Sources
Hydraulic noise
Certain amount of
created by
noise level acceptable,
pressure
not a safety critical
impulses.
item.
Possible Sources
Power steering
return lines.
High power assist
gain of power
steering gear
valve (steering
gear design - no
quality issue).
High power
steering pump
(211-00
Action
Action
Certain amount
of noise level
acceptable, not a
safety critical
item.
Certain amount
of noise level
acceptable, not a
safety critical
item.
Certain amount
of noise level
acceptable, not a
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