Troubleshooting a Whirring Sound Under the Hood

man under hood
DIY owners are always inspecting and troubleshooting their vehicles. Getty

You drive your car or truck every day. Whether you’re commuting to work or taking some precious kid cargo to and from their endless string of activities. With so much seat time, you get to know your vehicle pretty well. That’s why you should always trust your instincts when things start to feel, or sound, wrong. 

What’s That Whirring Sound Under the Hood? 

Your engine is a finely tuned machine. It makes noise under the hood, but the noise you hear is usually predictable and relatively quiet.

You press the accelerator pedal, the engine runs faster, you release, it slows down to a smooth idle. When things aren’t right, you know it. A whirring sound that rises and falls with engine RPM can be a sign of a minor adjustment need or a serious repair on the horizon. 

Symptom: Low, Growling Sound When Turning the Steering Wheel

Possible Causes: If you are experiencing a low, cyclical growling sound when you turn the steering wheel, the first question is whether it happens when the car is not moving. If you hear a whining, growling sound when the car is sitting still, it’s coming from your power steering. You might just be low on power steering fluid, which is an easy fix. You also might have a problem with your power steering pump, or the steering rack. These are much tougher repairs. Take a look at the ground to see if you have any leaks, and what they might be.

Symptom: Excessive Noise at Engine Pulleys

Possible Causes: Any time you hear a cyclical sound from the front of your engine, where the belts are, you should check it out.

If it sounds much louder than usual, you may have a bad bearing or pulley on one of your belt driven parts — the alternator, power steering pump, water pump, AC compressor or supercharger could all be the culprit. The closer you can pinpoint the sound, the better, but never try to put your ear in the engine compartment to listen!

Hair, clothing, or even fingers can get caught in the turning pulley and moving belts, with catastrophic results. 

Symptom: Loud Whirring or Clicking

Possible Causes: If you have a loud whirring or clicking sound that changes with engine speed, your radiator fan could be the culprit. If one of your radiator fan blades gets even a little out of whack, it can start to vibrate, or even contact the fan shroud around it. This is a very noisy condition, but usually not an expensive fix. Replace the fan or bend the shroud back out of the way. If your loud whirring or clicking does now get louder when the engine is revved higher, it may be an electric fan. Open the hood while you can hear the noise and see if your fan is on. If it’s making noise, it may need to be tightened or straightened. 

WARNING: An electric fan can come on at ANY time, even if the car is off. Never work on an electric fan without first disconnecting the battery!

Remember, it’s always wiser to spend more time diagnosing and less time fixing. The shotgun approach to car part replacement is almost always a waste of time and money. If you aren’t sure what the problem is, sometimes it’s a smarter choice to take the car or truck in to a professional to pinpoint the problem.