Symptom Definitions

Steering System Symptom Definitions
Some amount of these steering noises is considered acceptable. If in doubt of the acceptability, compare to another vehicle.

Drift/Pull
Pull is described as a tugging sensation felt by the hands on the steering wheel that must be overcome to keep the vehicle going straight.

Drift describes what a vehicle with this condition does with the hands off the steering wheel.
^ A vehicle-related drift/pull on a flat road can cause a consistent deviation from the straight-ahead path and require constant steering input in the opposite direction to counteract the effect.
^ Drift/pull can be induced by conditions external to the vehicle, such as wind or road camber.

Excessive Steering Wheel Play
Excessive steering wheel play is a condition in which there is too much steering wheel movement before the wheels move. A small amount of steering wheel free play is considered normal.

Lack of Assist or Inconsistent Assist
Lack of assist or inconsistent assist is experienced when the steering wheel effort is higher than normal. Hard steering can remain constant through the full turn or occur near the end of a turn. It is important to know the difference between hard steering/lack of assist and poor returnability/sticky steering.

Hard steering or lack of assist can result from either hydraulic or mechanical conditions. It is extremely important to know if this concern occurs during driving or during high-effort parking maneuvers.

Poor Returnability/Sticky Steering
Poor returnability and sticky steering is used to describe the poor return of the steering wheel to center after a turn or steering correction is completed.

Wander
Wander is the tendency of the vehicle to require frequent, random left and right steering wheel corrections to maintain a straight path down a level road.

Steering System Noise Definitions

Belt Squeal
Belt squeal is a high frequency air-borne noise generated by accessory drive belt slippage on the P/S pump pulley. Squeal increases with system loading and at the steering stops.

Chirp
A short-duration high-pitched noise associated with a slipping drive belt.

Clonk
Clonk is a structure-borne noise heard as a loose-sounding rattle or vibration coming from the steering column. Clonk is identified by driving and turning over cobble stones, rough roads or high frequency bumps, such as 1-2 inch tall tar strips or frost heaves. Clonk is a noise heard only while cornering over bumps. Clonk requires a tie-rod load impact. Clonk can sound identical to Column Knock, that also occurs when driving over cobble stones or rough road. Clonk may appear to emanate from a location closer to the floor than for column knock.

Clunk
A heavy or dull, short-duration, low-frequency sound that can be temperature sensitive. Clunk can occur when accelerating or decelerating abruptly. Also described as a thunk. Clunk can also occur when cornering over a bump.

Cold Start Noise
Cold start noise is the air-borne noise generated by pump cavitation when hydraulic fluid does not flow freely through the suction hose from the reservoir to pump. Zip is primarily a cold weather start-up phenomenon. 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).

Column Rattle
Column rattle is a metallic sounding noise created when applying a highly impulsive force to the steering wheel. Column rattle is often used to combine the more general group of column noises including Clonk and Knock. Column rattle noises can be caused by clonk, knock, loose column components, extra loose parts such as fasteners or broken plastic pieces, etc. A series of parked, straight-line driving and cornering tests must be used to isolate the source(s).

Hiss
Hiss or valve hiss is a high-frequency sound coming from the steering gear when the system is loaded. It is a rushing or "swish" noise that does not change frequency with rpm. Hiss is the general noise generated by flow of hydraulic fluid though restrictions in the steering system and typically worsens with increasing temperatures. Restrictions include the rotary steering valve, power steering tubes, connectors, tuning orifices, etc. Hiss can be air-borne and structure-borne, but the structure-borne path through the steering intermediate shaft is usually dominant.

Grinding
Grinding is a low frequency noise in the column when the steering wheel is turned. This is generally caused by interference between moving components, such as steering wheel to shroud.

Grunt (Squawk)
Grunt is a "honking" sound elicited when coming off one of the steering stops. The phenomenon may also be tactile. Grunt is a structure-borne noise (and vibration) generated at the steering valve. Grunt frequency is system dependent and in the range of 30 Hz to 200 Hz. Grunt is generally excited during parking maneuvers with a low to medium speed steering input.

Knock
Knock is a loose-sounding rattle or vibration generated by the steering column shaft contacting other portions of the column assembly. The noise is both audible and tactile. Knock is generated driving over cobble stones or rough pavement. It is not necessary to turn the steering wheel to create this noise.

Moan
Moan is the general structure-borne noise of the steering system. Moan is typically in the frequency range of 100 Hz to 600 Hz. Moan is primarily transmitted to the driver via body structure, through the pump mount, engine mounts, power steering lines and brackets. For problem vehicles, moan is a loud humming noise, often present when the wheel is turned and the system is loaded. It may change in frequency with rpm and if the system is loaded or unloaded.

Shudder
Shudder is a low frequency (10 - 20 Hz) oscillation of the entire steering system (tires, wheels, steering gear and linkage, etc.) when the vehicle is steered during static park or at low speeds. Shudder is very dependent on road surface.

Squeak
Squeaks are noises due to friction or component rubbing anywhere in the steering system. Squeaks have appeared in steering linkage joints, in steering column components, steering gear rotary seals and steering wheel trim parts.

Whine
Whine is the general air-borne noise of the P/S pump. Whine is in the frequency range of 1 kHz to 4 kHz. Whine is generated when engine rpm, pump rotational natural frequency and pump/bracket natural vibration frequency align.

Whistle
Whistle is similar to hiss but is louder and of a higher frequency. It is also more of a pure tone noise than hiss. Whistle is air-borne and is generated by a high flow rate of hydraulic fluid through a small restriction.