Noises in steering system, troubleshooting · ad4600d500003a · Mercedes-Benz WIS

AD46.00-D-5000-03A

Noises in steering system, troubleshooting

Model

414, 636, 638, 639, 690, 900, 901, 902, 903, 904, 905, 906, 909

General check/assessment of noises in steering:

 Check whether the steering noise can be reproduced.

 Check whether the customer is complaining about a series production configuration; compare with a reference vehicle if necessary.

 Check whether the noise occurs when the engine is cold or warm.

 Check whether the noise is the same when steering left and steering right.

 Check exactly when the sound can be heard. When stationary/parking or when driving.

 Check whether the noise only occurs at certain steering wheel positions/angles or over the entire steering range.

 Check whether the noise is produced together with mechanical feedback felt at the steering wheel, e.g. vibrations, actuation point, tugging, slight jamming, etc.

 Check whether the noise is caused by play in the steering. If so, continue with Play in steering system - Troubleshooting".

 Check whether noise can be reproduced on the lifting platform. Is the noise also present when the wheels are under no load or only when the wheels are loaded?

 Check whether the noise can be reproduced. Is one of the following categories applicable (see table)?

Troubleshooting based on noise type
Noises	Notes
Squeaking noises (squeaking of rubber)	Squeaking noises are usually temperature-dependent since they are caused by the friction of plastic or rubber parts and the amount of friction changes according to the temperature. - Determine whether the noise comes from the vehicle interior or from outside. - Check whether the noise is temperature-dependent. At what operating temperatures or outside temperatures does the noise occur? - Check whether the noise comes from the steering column tube boot (check using your fingers). Remove the boot if necessary and check whether the noise can be heard after the boot has been removed. - Check whether the noise changes at different steering wheel positions (or steering column positions). - Can the noise only be reproduced when the engine is running or also without power assistance?
Grinding noises	Determine whether the noise comes from the vehicle interior or from outside. - Check which parts are rubbing (trim parts, floor insulation mat, clock spring contact, steering wheel, steering shaft, tie rods). - Check whether the noise changes at different steering wheel positions (or steering column positions). - Can the noise only be reproduced when the engine is running or also without power assistance? - Check in the center position whether the boots of the steering gear are S-shaped. If so: Check whether the noises are produced there when the steering is moved and the boot moves over the axial joint.
Hydraulic noises	Hydraulic noises can be heard in the hydraulic circuit (pump, hoses, steering gear) and often only occur during certain steering procedures associated with other parameters such as temperature and engine speed. - Check whether the noise is dependent on the operating temperature. Cold/warm? - Check whether the noise changes during steering.
Hissing/whistling noises	A hissing/whistling noise is a high-pitch noise that is usually caused by rough edges or foreign objects in the hydraulic circuit. - Check whether the noise is dependent on engine speed. - Check whether the noise is the same in both steering directions or if it is only produced in one steering direction. - Check whether the noise also occurs without the steering wheel being turned (continuous flow), when the steering wheel is turned slightly and held in this position (without the wheels being moved) or if the noise occurs only during actual steering procedures (wheels are turned).
Hooting noises	A hooting noise is a clearly audible and relatively loud noise. It can occur briefly during parking. This noise is the sound of resonant vibrations in the steering valve. It is dependent on the steering oil temperature and the steering speed. Depending on its condition, the lower radial shaft sealing ring in the steering gear housing can also cause a hooting noise. - Check at what operating temperature the noise occurs. - Check whether the noise is dependent on the engine speed. - Check which steering movements cause the noise to occur. When turning in or turning back? Left/right? - Check whether the noise is dependent on the steering speed. Turning the steering wheel quickly or slowly. - Check whether the noise can be heard when the wheels are relieved of the weight of the vehicle. - Check whether the noise can be heard with and without the engine running.
Humming/creaking noises	A humming/creaking noise is a low-frequency noise which often occurs in connection with vibrations felt at the steering wheel, and is usually produced when air enters the steering (oil level too low or if the steering was not correctly bled after repair work). - Check whether the oil level in the reservoir is OK. Does the oil foam up in the reservoir? Is the oil moving around too much in the reservoir? Irregular engine operation or changes in engine speed can also cause humming noises. It is therefore necessary to ensure that the engine is running properly before any further checks are performed. - Check whether hydraulic lines make contact with other components. Check while moving the steering since the hydraulic lines can move. - Check whether the noise is dependent on the operating temperature. - Check whether the noise is dependent on engine speed. - Check whether the noise can be heard equally in both steering directions. - Check which steering procedures cause the noise to occur. At the steering stop or already in the center position. Steering noises just before or at the steering limit are normal and are no cause for complaint as the system is subjected to extremely high pressure at this point and noises are inevitable.
Cracking noises	A cracking noise can be heard above all when steering while the vehicle is stationary or during parking maneuvers, and there is a direct correlation between the noise and the movement of the steering wheel. Only assess with the engine running! - Check whether the cracking noise occurs when continuously steering in one direction or whether the noise always occurs when changing the steering direction (changing from steering right to steering left, and vice versa -> cracking noise when changing the steering direction). Note that a minimum amount of play is required in the steering gear and if the vehicle is stationary, this play can be heard to a small extent when changing the steering direction. This noise is related to the design of the steering system and is therefore not a cause for complaint. A cracking noise is a mechanical noise and is usually caused by play. If the cracking noise occurs when the steering direction is changed: - Carry out assessment using a reference vehicle. - Check whether the cracking noise always occurs at same steering wheel position/angle. - Check whether the cracking noise occurs predominantly at the center position or more towards the steering limit. - Check whether the noise is dependent on temperature. If so, how? Operating or outside temperature. - Check that all threaded connections (universal joints, steering column, steering gear, firewall pivot point) are securely tightened. - Check whether there is play at any point.  See "Play in steering system - Troubleshooting". - Check the universal joints for play. - Check the axial joints of the tie rods and tie rod ends for play. - Check whether an actuation point can be felt at the same time. - Check the ease of movement of the sliding piece; if necessary, improve ease of movement using multipurpose oil.
Rattling/knocking noises	Rattling/knocking noises only occur when driving and are caused by the condition of the road/terrain (road surface condition, pot holes, etc.). - Check whether the rattling/knocking noise is influenced by steering movements or if it occurs irrespective of them. Note that the rattling/knocking noises may be caused by many other reasons which are not associated with the steering system and which must also be checked. - Check under which driving conditions (acceleration/deceleration, speed) and on which kind of road/terrain (kind of road surface, pot holes) the rattling/knocking noise occurs. - Check whether the rattling/knocking noise occurs predominantly in the center position or when the steering wheel is turned. - Check whether the noise is dependent on temperature. If so, how? Operating or outside temperature. - Check that all threaded connections (universal joints, steering column, steering gear, firewall pivot point) are securely tightened. - Check the play at the steering column tube, universal joints, steering gear and tie rods.  See "Play in steering system".

Troubleshooting based on components
	Component	Notes	Remedy
1	Trim parts/ clock spring contact	Grinding noise A grinding noise coming from the vehicle interior is usually caused by a trim part or the clock spring contact rubbing against another part, whereby the noise occurs independently of whether the engine is running, but is often associated with the steering wheel position.	Locate and eliminate the noise.
2	universal joint	Rattling/knocking A possible cause of rattling/knocking noises when changing the steering direction or on rough roads is the universal joints, whereby play must be detectable in the universal joint.	Replace the lower steering shaft and/or steering column if necessary.
3	Steering column tube boot	Squealing	- Check that the boot of steering column tube is seated correctly; correct if necessary. - Grease slide surfaces of firewall pivot point and steering column tube boot. - Grease surface of steering column tube boot that has contact with steering shaft and, if necessary, its outside surface.
4	Steering column tube/steering shaft	Cracking A cracking noise occurring when the sliding piece of the steering column moves is due to the design and is not a cause for complaint. Cracking noises can also be attributable to a damaged steering shaft bearing (chatter marks can be felt when steering).
		Steering shaft bearing OK 	A cracking noise can be heard as a result of tension along the steering column. Release the steering column mount, detension and secure again.
		Steering shaft bearing not OK 	Replace the steering column.
5.1	Steering gear	Humming/creaking These noises do not occur as a result of problems in the steering gear but usually have other causes.
5.2	Steering gear	Cracking These noises can be heard when changing the steering direction and may originate from the steering gear if there is excessive play at the thrust piece. Radial play in the steering gear and therefore a slight noise when changing the steering direction is caused by the design of the steering system and is not a cause for complaint. All other causes (steering column, universal joints) must be checked before installing a new steering system. Note: The engine must be running for this noise to be assessed.
		Steering gear causes noises 	Check thrust piece play; adjust if necessary.
5.3	Steering gear	Beeping These noises can be produced at the control valve on the steering gear: Contact workshop service; a modified hose variant may be available. Note: See also "Squeaking". Depending on its condition, the lower radial shaft sealing ring in the steering gear can also cause a hooting noise.
5.4	Steering gear	Rattling/knocking These noises are mainly attributable to play at components. Check the axial joints of the tie rods and tie rod ends for play (the boot must be removed in order to check the axial joint of the tie rod).
		Play present 	Replace the affected tie rod with axial joint and tie rod end.
		No play present 	Check surrounding axle components for play: - Play present: Locate and eliminate noise. - No play present: Play in steering gear provided that all other possible causes have been ruled out: Check thrust piece play; adjust if necessary.
5.5	Steering gear	Squealing These noises may be caused by the steering gear, provided that the steering column tube boot together with surrounding components and the suspension strut mounts have been ruled out as possible causes.	Pour in Lubrizol.
		Noise still present after pouring in Lubrizol 	Replace steering gear.
5.6	Steering gear	Grinding All other possibilities must be checked before the steering gear can be considered as a possible source of the noise. Grinding noises are rarely caused by a problem with the steering gear. The steering gear must only be considered as a possible cause if the noise has been located as originating in the engine compartment and all other causes have been ruled out. S-shaped bellows can be replaced separately.
		If no other cause comes into consideration 	Replace steering gear.
5.7	Steering gear	Hissing/whistling It can be safely assumed that a hissing/whistling noise is caused by the steering gear if the noise only occurs when steering in one particular direction. If the hissing/whistling noise occurs when steering in both directions and the high-pressure line has been eliminated as a possible cause: Pinpoint the location of the noise using a stethoscope.
		If noise is not caused by steering gear 	Replace steering gear.
6	Power steering pump	Note: Cold-starting properties: At very low temperatures, pump noises are possible and permissible for approx. 5 to 10 s after the engine has been started. Check whether surrounding components are causing the noise (e.g.: engine, belt drive or refrigerant compressor). With engine-mounted pumps, there is a direct correlation between the noise and the engine speed. The following test results must be available before the power steering pump can be identified as the source of the noises: - Oil level OK - Oil is not foaming or does not exhibit any significant swirling. See also TIPS documents: - "Noises from area of steering pump" - "Flow noises from area of power steering pump and/or foaming of power assist oil in oil reservoir"
		Test result according to TIPS OK 	Replace power steering pump.
		Oil level not OK 	Check the steering for leakage (if necessary, also partly detach the boot at the steering gear): Eliminate any leakage. Fill oil up to maximum level.
		Oil is foaming or swirling in oil reservoir:
		- Air in hydraulic system 	Completely drain the hydraulic fluid from system, refill and bleed.
		- Filter in oil reservoir defective 	Replace oil reservoir of power steering pump or power steering pump with oil reservoir.
7	High-pressure hose	Hissing/humming In addition to carrying the hydraulic fluid, high-pressure steering hoses also serve to dampen any vibrations from the engine and power steering pump so that no vibrations can be felt or noises heard at the steering wheel. The high pressure hose may be the cause if hissing noises can be heard when steering in both directions and the hissing noise occurs independently of the engine speed. The high-pressure hose may be the cause if humming noises occur when steering in both directions (possibly together with vibrations).	Replace high-pressure hose.
8	Oil reservoir	Humming, creaking If the filter in the oil reservoir is defective and the oil returning to the reservoir is not settled sufficiently, the oil can foam even though the oil level is correct, and cause a humming/creaking noise. This is identifiable by clear signs of a flowing/whirling motion in the oil in the reservoir when the engine is running.	Replace oil reservoir of power steering pump or power steering pump with oil reservoir.