Diagnosing Steering System Noises
Screeching, whining, grinding and popping — all types of noises associated with the steering system! Unusual noises the result of steering system operation can sometimes be challenging to diagnose. In this article, we list a host of potential noise sources, with regard to steering column, power steering pump, steering linkage and related components that can contribute to the generation of unwanted and disconcerting noises.
The most common cause for power steering noise is low power steering fluid level. The resulting noise will likely be a whining that is heard when turning the steering wheel. A high-pitched or “screeching” noise is usually caused by a worn or misadjusted power steering drive belt.
A grinding or popping noise may be caused by worn or damaged upper strut bearings, which may be heard when turning the wheels. This can often be misdiagnosed as a steering system issue.
Wrong P/S fluid
In the “good old days,” it was common for ATF to be used in power steering pump systems. Today, it is imperative to use only the specific power steering fluid recommended by the vehicle manufacturer. Using the wrong type of fluid can create varied problems from aeration to pump seal damage. Using a “generic” “power steering fluid” that claims to be compatible for “all” systems does not guarantee proper operation. If in doubt, always check the service or owner’s manual for the correct type of fluid. Specific power steering fluids may be mineral based or synthetic, depending on application.
Listed here is a guideline of the fluids recommended by various auto makers. Always check, as this can vary depending on the specific model and year.
Acura -- Honda P/S fluid
Audi -- Pentosin CHF 7.1, CHF 11S or CHF 202, depending on year.
BMW -- Pentosin CHF 7.1 or CHF 11S, depending on year
Chrysler -- P/S fluid (pre-1998) or ATF+4 1998 and later) or Pentosin CHF 11S
Daewoo -- Dexron II or III
Dodge Sprinter -- Pentosin CHF 11S
Ford/Lincoln/Mercury -- Mercon ATF
GM -- P/S fluid
Honda -- Honda P/S fluid
Hyundai -- P/S fluid 3 or Dexron II
Jaguar -- Pentosin CHF 11S or Dexron III
Jeep -- WK Hydraulic, ATF+4 or P/S fluid (depending on model)
Infiniti -- Dexron III
Isuzu -- Dexron II or III
Kia -- P/S fluid or Dexron III (depending on model)
Land Rover -- Dexron II or III
Lexus -- Dexron II or III
Mazda -- Dexron III
Mercedes-Benz -- Pentosin CHF 11S or P/S fluid
Mini -- Pentosin CHF 11S
Mitsubishi -- P/S fluid or Dexron II
Nissan -- 1994 and later... Pentosin CHF 11S
Nissan/Datsun -- Pre-1994... Dexron III
Porsche -- Pentosin CHF 11S or CHF 202
Rolls Royce -- Pentosin CHF 11S
Saab -- Varies by application
Saturn -- P/S fluid
Scion -- Dexron II or III
Subaru -- Dexron II or III
Suzuki -- Dexron II or III
Toyota -- Dexron II or III
Volkswagen -- P/S fluid, Pentosin CHF 11S, Pentosin CHF 202 (varies by year)
Volvo -- Pentosin CHF 7.1, CHF 11S, CHF 202 (varies by year)
NOTE: Pentosin 7.1 is mineral based, while Pentosin CHF 202 and CHF 11S are synthetic fluids.
Never mix power steering fluid types. If the wrong fluid has been introduced, flush the system, add the correct fluid and bleed (“burp”) air from the system. This is generally done by turning the steering lock to lock slowly several times, but always check with the service manual for the vehicle at hand.
Power steering hoses
When power steering hard lines must be replaced, be aware that some bargain-brand lines may be made with a thinner wall than OE lines, which can result in harmonics to be transferred through the lines, creating a whine or high-pitched noise. Also, power steering pressure hoses vibrate under high pressure.
If the hoses contact the body, frame or engine, this can easily result in a “mystery” noise. Make sure that hose contact is avoided by relocating hoses and making sure that any clamps or hold-down clips are not missing.
Evidence of power steering fluid foaming and noise may be caused by a faulty power steering return hose (hose might be loose, brittle, cracked, damaged with pinholes, etc.), which may be allowing air to be sucked into the system.
Run the engine to normal operating temperature, and then shut off the engine. Gently pressurize the power steering pump reservoir with no more than 8 psi air pressure, and inspect the return hose for leaks. Replace the damaged return hose and bleed the system.
If a customer complains of a noise when turning the steering wheel right or left, check the brake calipers and caliper brackets.
If bolts are loose or missing, this may be the culprit.
If the customer complains of a clicking noise during tight slow turns (turning into a driveway, making a turn from a stop sign, etc.), and the vehicle features front-wheel-drive, immediately suspect worn/dry CV joints. If the condition is ignored, total CV joint failure will occur, resulting in a no-drive situation.
If the customer complains of a humming, rumbling or growling noise that increases as the steering wheel is turned, consider the front hubs. If it’s a hub issue, this may be accompanied by a steering wheel vibration during turns, and excessive play in the steering wheel, and a possible pull to one side during braking.
Power steering pump issues
If the power steering pump is noisy, accompanied by a lack of power assist, air is likely trapped in the system. Perform a basic system inspection for hose condition, fluid level and fluid condition.
If the fluid appears burnt or contaminated, flush the system. Most systems can be bled of air by first filling the reservoir to the “cold” mark. With the vehicle raised off the ground and with the engine off, slowly turn the steering wheel to full lock in one direction and wait for five seconds. Then slowly turn to full lock in the opposite direction and wait five seconds. Repeat this cycle 15 to 20 times, regularly checking fluid level as you proceed. Continue until the fluid looks normal and no foaming is evident.
Some systems may be difficult to bleed (some Fords, for example). If a whine or moan noise is evident at the pump, air is in the system. A Devac vacuum tool may be used to address problem bleed issues. Fill the pump reservoir and insert the vacuum tool’s rubber stopper into the reservoir fill neck. With the engine running at idle, apply 15 inches of vacuum to the reservoir. Cycle the steering wheel from full lock to lock every 30 seconds for about five minutes. Be sure to maintain 15 inches of vacuum during the operation.
Shut the engine off, release vacuum and remove the vacuum tool. Top off the fluid and reinstall the reservoir cap/dipstick. Re-start the engine and cycle the steering wheel, checking for leaks at all hose/line connections. It may be necessary to repeat this process several times in the case of a stubborn air pocket.
Don’t automatically assume that a noise is caused by the power steering pump. A noise that seems to be coming from the power steering pump might not be a pump issue, as it might be created by another source. According to Cardone, examples are 1992-1993 Chevy and GMC trucks and Oldsmobile Bravada vehicles equipped with a 4.3L, 5.0L or 5.7L engine. A whining noise may appear to be at the pump, when the noise may actually be the result of a failed bearing in the alternator.
1. Isolate the power steering pump from the alternator by removing the existing drive belt and installing a belt part numbered for a 1993-1994 Camaro or Firebird (this allows you to remove the power steering pump from the drive system).
2. Run the engine (do not drive the vehicle) and listen for the noise. If the noise is gone, then the problem points at the power steering pump. If the noise remains, proceed to diagnose the remaining driven components including the alternator.
3. Once the faulty component has been replaced, install the correct drive belt and confirm the repair.
GM rack and pinion noise
As noted by Cardone, complaints related to a clunking noise during low speed turns have been noted on 2004-2010 Chevy Malibu, Pontiac G6 and Saturn Aura models. The manual rack and pinion is part of the EPS (electronic power steering system). EPS systems provide assist only when needed, so the driver feels when the motor engages/disengages for assist-on/assist-off driving. The different torque characteristics of this system are not typical of a hydraulic system. The noise complaint is most likely due to three possible conditions:
– Intermediate shaft sticking or slipping.
– Interference between the intermediate shaft clamp and the steering gear input shaft.
– Strut mount or anti-sway bar link condition.
There is also a precise mounting bolt torque specification that must be followed to ensure that the rack is properly mounted to the frame.
If this specification is not followed, vibration can lead to a misdiagnosed noise. The rack mounting bolts must be tightened to 53 ft.-lbs., plus an additional 90 degrees of rotation (torque-plus-angle method).
A GUIDE TO PROBLEMS AND CAUSES
Steering system cold-start noise
Power steering fluid blockage caused by contamination in the reservoir and/or lines.
Some noise during an extremely cold start (-10 degrees F) is normal and should improve as the system warms.
Also, air in the power steering system can cause the same issue. Check for leaks and purge air from the system.
Steering grunt or shudder when turning the wheels at low speed.
This may be caused by air in the power steering fluid circuit, deteriorating system hoses or steering gear wear.
Power steering pump moan/humming sound when the steering wheel is turned to a stop position.
Consider low power steering fluid level, air in the PS system, insufficient PS fluid flow due to reservoir or screen blockage, power steering line or hose grounded to the chassis, or steering gear isolator damage.
Steering gear clunk noise when driving over a bump.
Steering gear wear or steering gear mounting is loose.
Belt squeal or chirping when turning the steering wheel lock-to-lock.
Belt tension, belt glazing, belt misalignment, pulley damage or pulley alignment, worn belt tensioner
Power steering hiss or whistle noise.
Steering column shaft or coupling bind or misalignment. Also check for a grounded or loose steering column bracket, damaged or worn steering gear input shaft and valve wear, or restricted power steering lines/hoses. This could also be caused by a noisy valve in the power steering gear.
Rattle or clunk noise.
Check for loose column brackets and fasteners, worn, loose or dry column bearings, worn or damaged steering shaft insulators, or a compressed or extended steering column shaft/coupling. Also check for a loose power steering gear, loose front suspension crossmember mounting fasteners, loose inner/outer tie rods, loose strut assembly mounting, power steering fluid pressure hose contacting the body, or a damaged power steering gear.
Squeak or rubbing noise.
Incorrect power steering fluid for the vehicle (for example, using ATF instead of power steering fluid). Also check for bad steering gear seals. Another culprit may be a bent or improperly positioned steering shaft stone shield. Also check for steering column shaft rubbing.
Steering column squeaking/grinding.
Dry steering shaft bushings, loose or misaligned column shrouds, upper or lower bearing sleeves out of position.
Noisy power steering pump relief with fluid temperature below 130 degrees F.
Power steering fluid flow into the bypass valve in the pump valve housing. Normal condition.
Power steering pump whine or growl noise.
Low power steering fluid level, aerated power steering fluid. Check for fluid leaks and purge system. Worn power steering pump.
Sucking air sound.
Check for lower fluid level, a missing or damaged O-ring on the power steering hose connection or a loose clamp on the fluid return line. An air leak between the fluid reservoir and pump may also be a culprit.
Steering gear contacting adjacent components, worn steering gear internal stops.
Electric power steering (EPS)
Some vehicles feature electric power steering systems. For details concerning EPS, refer to the September/October 2015 issue of Auto Service Professional (available on www.autoserviceprofessional.com) for an overview article by contributor Jacques Gordon. ■