What is causing the whining sound in my car engine?
April 27, 2009 10:05 AM   Subscribe

What is causing the whining sound in my car engine?

2001 Honda CRV with about 68,000 miles on it. I purchased the car about 6 months ago, and a few months after that noticed a slight whining noise coming from the engine. It sounds similar to a remote control car or small electric motor, and the pitch raises up when the engine speeds up. It doesn't happen all of the time, but seems to be louder when going up hill.

A few days ago I was driving on the freeway for about 20 minutes, and once off of the freeway was driving on hilly side streets. For the first time the noise started to be very noticeable, and got progressively louder and louder. I shut off the car, went away for about an hour, and when I started driving again the noise was gone.

Any suggestions as to what the problem might be? I plan on taking it to a mechanic soon, but I'm pretty handy and have a fairly well stocked toolbox, so if it is something I can do myself I would prefer to go that route.

posted by markblasco to Travel & Transportation (12 answers total)
Response by poster: Oh, I just had the belts replaced (they were looking old and in need of replacement), and the noise was happening before this, so I don't believe it to be a belt problem.
posted by markblasco at 10:06 AM on April 27, 2009

Since the pitch varies with engine speed, I would think of things that are driven by the engine: power steering pump (check the power steering fluid), AC compressor, water pump, and so on.
posted by TedW at 10:10 AM on April 27, 2009

My jeep's power steering pump made this kind of noise for about a year before it went kaput.
posted by M.C. Lo-Carb! at 10:11 AM on April 27, 2009

Did you check all the fluids? Power steering can whine when fluid levels get low.
posted by Big_B at 10:11 AM on April 27, 2009

Is it a stick? My transmission whined awhile before it commuted seppuku all over I-80. On your behalf I will hope that power steering fluid is the solution to your whine, because a new transmission cost me $1300.
posted by small_ruminant at 10:34 AM on April 27, 2009

Response by poster: It is an automatic. I hadn't thought of the power steering, since the noise doesn't change when turning the car, but I will check the fluid when I get home.
posted by markblasco at 10:48 AM on April 27, 2009

Are you sure it is coming from the engine, or could it be front wheel bearing noise?
To check, see if the noise happens when the car is parked and you rev the engine in neutral.

The wheel bearing noise will only happen when the car is moving, of course.

If you have a friend do the revving while you listen under the hood, you will be better able to pin point it.
posted by artdrectr at 11:00 AM on April 27, 2009

Check out the belt tensioner; make sure it's not too tight, and that the pulley is properly lubricated.

If that doesn't fix it, ask your mechanic about timing belt issues (fairly soon).
posted by jamjam at 11:04 AM on April 27, 2009

Given that the whining was there, then the belts were replaced, quite possibly increasing the load sustained by all the pulleys; and given that it is engine-speed-related, my first check would be the alternator. If you have good access to it when the hood is open, have someone change engine speeds while you listen to the alternator. You can isolate under-hood sounds by resting the tip of a screwdriver on a non-moving part of the device of interest, and putting your ear on the other end of the screwdriver.
posted by jet_silver at 12:12 PM on April 27, 2009

I'm pretty sure that this isn't it, but I once had a fairly minute twig caught someplace around the engine and it took me a lot of searching to get rid of the noise: whining, changing when the engine speeds up, and sometimes inexplicably louder or gone, and back again...just a thought.
posted by Namlit at 12:15 PM on April 27, 2009

You can use a piece of tubing up to your ear to localize the sound. Use extreme care around the fan and belts while doing this.
posted by fritley at 12:27 PM on April 27, 2009

The serpentine belt. The belt no one ever thinks to replace.
posted by Zambrano at 1:38 PM on April 27, 2009

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