Why Is My Car Making a Whining Noise When Turning?

A whining noise when turning the steering wheel is most often low power steering fluid, or air drawn into the system because the fluid is low. The pump is built to move fluid, not air, and when it pulls in air it whines or moans in time with engine speed. The sound is loudest at full lock, because that is when the pump works hardest, and it is usually worst on a cold start and quieter once the car warms up. Check the fluid level first. It is the cause in most cars that come in with this complaint.

Low Fluid Or Air In The System

A hydraulic power steering system is sealed. It does not consume fluid. If the reservoir is low, fluid is getting out somewhere and air is getting in to take its place.

Air is what makes the noise. Aerated fluid does not behave like solid fluid, so the pump cavitates and whines. The fluid in the reservoir often looks foamy or milky.

Common leak points are the pressure hose, the return hose, the pump shaft seal, and the rack seals. A rack leak usually shows as fluid soaking the boots at the ends of the rack. Road salt is hard on the crimped fittings on steering lines, and a line that looked fine in the fall can weep by spring.

How To Check Power Steering Fluid

• Engine off. If it has been running, let it cool. The fluid gets hot and the reservoir sits near the belt.
• Find the reservoir. The cap is usually marked with a steering wheel symbol. Some have a dipstick in the cap, some are translucent with MIN and MAX lines, and many have separate hot and cold marks. Read the level against the mark matching engine temperature.
• Look at the fluid. New fluid is clear, red, or amber depending on type. Dark brown or black fluid that smells burnt is worn out. Foamy means air.
• If you top it off, use exactly what the owner's manual specifies. Some vehicles take automatic transmission fluid, others a specific power steering fluid, and the wrong one can swell or shrink seals.

If you are topping it off again a month later, stop and find the leak. Running a pump low on fluid is what turns a hose repair into a pump repair.

Other Causes Of A Whine When Turning

If the fluid is full and clean and the whine persists, work down this list.

• Failing power steering pump. Worn vanes or bearings whine even with a full reservoir. The noise is there at idle and gets louder as you turn. Steering may feel heavier than it used to at parking-lot speed.
• Slipping or glazed serpentine belt. The belt drives the pump. Turning the wheel spikes the pump load, and a worn, glazed, or loose belt slips on the pulley. That is usually a squeal or chirp rather than a true whine, but it gets described as whining often enough to check. A failing tensioner does the same.
• Restricted return line or clogged filter. Some systems have a screen in the reservoir or an inline filter, and debris from a wearing pump or rack can plug it. A kinked or collapsed return hose does the same. Either one starves the pump.
• Worn steering rack. Internal wear lets fluid bypass the piston. The whine is often worse turning one direction than the other, and steering can feel loose on center.

Electric Power Steering Is A Different Problem

Many newer vehicles use electric power steering. There is no pump, no belt, and no fluid, so topping anything off will not help.

On those cars a failing assist motor or a worn column coupling makes a different sound: an electric whirr, a buzz, or a fine grinding that tracks how fast you move the wheel rather than engine RPM. That is the key difference. A hydraulic whine follows the engine. An electric steering noise follows your hands. The fix there is diagnosis of the assist unit, not fluid.

Whining, Grinding, And Clicking Point To Different Parts

The word you would use narrows the search a lot.

• Whining or moaning that rises with engine speed and peaks at full lock: power steering.
• Grinding that rises with road speed and changes as you lean into a curve is usually a wheel bearing. Grinding or creaking from the top of the strut in slow turns is a strut mount.
• Clicking or popping in a tight turn, often under light acceleration, is a worn outer CV joint. It tracks wheel rotation, not engine RPM.

Why This Shows Up On Cold Mornings

Cold thickens power steering fluid. On a Minnesota winter morning the pump moves fluid far heavier than it was in August, and that strain makes a marginal system speak up. A whine that shows up on cold starts and fades as the car warms usually means the fluid is low or broken down. Better to hear it now than lose assist in a parking lot in February.

When To Get It Looked At

• Right away: whining plus steering that feels heavy, grabby, or intermittent. That is assist on its way out.
• Right away: fluid dripping under the front of the car, or a reservoir that empties in days.
• Soon: a steady whine with a full reservoir, or dark burnt fluid.
• Soon: a whine that only shows up cold. Early is the cheap end of this repair.

Avoid holding the wheel hard against the stop while you sort this out. Full lock is maximum load on the pump and the fastest way to finish off one that is already struggling.

If your car whines when you turn and you would rather know whether it is a hose, the fluid, or the pump, we can pressure test the system and find the leak. Stellar Autoworks is in Plymouth, serves the west metro, and warranties qualifying repairs for 24 months or 24,000 miles. schedule service and we will take a look.