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Revving noise under hood like weed eater, which stops when step on gas

this just happened to my 1997 explorer: I heard a revving noise under the hood while traveling over 30 or 40 mph. The noise sounds like what a weed eater makes. The noise would continue even if the speed drops to below 30 mph. The noise would stop if I step on gas, and will return when I let off. The noise stops when car comes to stop. While car is stopped, I can rev the engine all I want and the noise will not occur.

What could be the problem? Fix?

Is this a electric weed eater under your hood or a 2 stroke weed eater?

This comparing car noises to other mechanical devices must stop.

Power steering pumps can make a whining noise when low on fluid and cavatating,best I have.

In 35+ years fixing cars and listening to customers I never had them comparing their cars to airplanes,helicopters,weed eaters and I was able to get the point. before.

It would be a electric weed eater. Sorry for using the comparing, but it was the best way I could think of describing a sound.

One more observation: While the noise was present, the engine rmp did not show it was higher. It appears the noise did not come from engine revving.

I will check to see if the power steering fluid level is low. Thanks.

This is a followup on the suggestion about checking the power steering fluid level. The fluid level is right below the MAX mark.

Does anyone have thought about why the noise stopped when stepped on the gas pedal, and returned when let go? The noise happens only when driving.

Is this revving sound at a steady pitch or is there a ‘wind up’ when it begins?

It could be a vacuum leak. Manifold vacuum drops [and the noise goes away] when you step on the gas. Also, if the vacuum line goes through a control valve it might only reach the part with the leak when cruising. Check the evap emissions system.

I actually Googled my 2013 Malibu sounds like a weed eater running under it and found this discussion so I would have to say he was spot-on for describing the noise and actually you knew what he was talking about to I think describing a comparable noise is a lot better than going Chiddy Chiddy Bang Bang Chitty Chitty Bang Bang

I would guess that you have a bad bearing in one of the devices that are driven by the serpentine belt.

The thing to do would be to loosen the serpentine belt and spin each pulley by hand, listening for any grinding noise
or feeling any wobble or roughness.


I wonder what it turned out to be? I was thinking it might be a wheel problem, even just loose lug nuts, or differential problem.

I hear you George! We might have to keep on wondering, George.
After 8 years @chungping either got it resolved or got accustomed to the sound. :slight_smile:

Sometimes it’s better to let sleeping dogs lie. :wink:

Who brings up this old crap.

I never noticed how old that post was.

They need to alloy people to read these old posts for information on their current problem, but these old posts should not be able to be brought up after a few months.


Old threads from forums show up on google type searches. They also show the date so why would someone even think a years old thread by unknown person was still relevant. Also why reply or ask a question of someone who has not been on this site for years, it isn’t like they have been sitting in front of their screen all that time.

People don’t pay attention to details; they don’t listen.
There was a recent segment on PBS with someone saying we aren’t evolved to listen.
I don’t remember the details of that segment. :roll_eyes:
Shows why pilots have checklists; why the soldiers in the missile silos go through strict regimens.

I suppose these people that find these threads are so eager to voice their opinions that they don’t even see how old the posting was or that the persons problem had been solved.


Recalling a time when posters were chastised for not looking up old threads. GET OVER IT. I get caught every once in a while for worthless dredgings of old posts, but others do have salient info, not a one box fits all.

The person that diagnosed this as a “VACUUM EVAP PROBLEM” is the only real mechanic. That was smart cuz the exact same thing happened when I messed up re-doing my EVAP system.