Humming coming from under the hood

jaredg16

New Member
Oct 30, 2008
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Found an old posting from a few years ago by a board member but never received a response back from him so I thought I'd repost it because it is the IDENTICAL situation I am having. From what i can tell it only happens when i first start the car after it has been sitting for a while. i start the car and when it comes down to idle (~750rpm) there is a noticible "howling" sound comming from the front of the car. i opened the hood and poked around, but couldnt see anything out of place. sound SEEMS to be comming from the drivers side of the engine near/at the front. does not matter if the lights, radio, or ac is on at the time. also does not go away when i depress the clutch or brake. if i play with the gas it will go away once i get the RPMs passed 1500, then return once it goes below that point. after i run it for a bit it goes away entirely even at idle. if you turn it off and start it back up it is still gone.

this howling sound has seemed to get a bit worse and is now starting to draw my attention more often. the best way to describe the sound is if you take a larger margaritta glass, put lime around the outside, then run your finger around the edge to get that "harmonic vibration" sound. I'm realy lost on this one.... any ideas?

Some have suggested that it MIGHT be the idler pulley getting ready to seize. Another suggestion was that it could be the idle air control valve. Any other suggestions?

Thanks in advance!

Jared

Oh, I have a 2003 V6 'Stang (no engine mods at all - everything stock).
 
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Noises like that can be pretty hard to track down sometimes, especially without bieng able to hear them in person.

Does it change pitch/tone if you turn the steering wheel? Power steering pumps usually whine when they become worn out or when the fluid is low. Same with waterpumps and pretty much everything else on the accessory drive, lol.

What you could do is remove the serpentine belt and spin and wiggle each pully to see if any are loose or require an excessive amount of force to turn.
 
Does it have a fan clutch? When they heat up, they do not make noise. But when it slow spins, it might have a bearing being it still rides in a shaft, so there as to be a bearing taking the load and chit.

Heat related is could be as simple as a the belt. She heats up, she is quiet. She all cracked on the groove side or has over 30K on it?
 
i have had a few fords come in for this problem. a truck and two crown vics with the same motor. all three of them were the idle air control system. take it off and clean it and also clean the passage in the plenum. this SHOULD take care of it. post back with results plz. :nice:
 
Thanks for the replies. I should also mention that it only does this humming once the engine is warm.

I will look into the idle air control and the plenum. I don't believe it'd be the power steering pump, as there's no change in the sound when the wheel is turned.

I'll repost once I can get to it. It may take a few weeks with christmas and all barking at the door. ;-)

J
 
Does it have a fan clutch? When they heat up, they do not make noise. But when it slow spins, it might have a bearing being it still rides in a shaft, so there as to be a bearing taking the load and chit.

Heat related is could be as simple as a the belt. She heats up, she is quiet. She all cracked on the groove side or has over 30K on it?

Nope, no fan clutch. 4.6 motors in Mustang's use an electric fan setup.