Help ID Engine Bay Whistle (not a whistletip!)

[Joshs]

I started up my car the other day to go to work, and there was a strange whistle sound which seems to come from the engine bay. It only sounds at idle, as once I give it a little gas it rises slightly in pitch then goes away.

My CCU is currently removed as it's being refurbed by BrianK, but I wouldn't expect that to be related..

Here's a video, you can hear it quite clearly:

http://www.youtube.com/watch?v=wRpw1szhNbo

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Any ideas?

-Josh


Reminds me of the Whistle-Tips video from a few years back: http://www.youtube.com/watch?v=ccgXjA2BLEY

 

[KooLaid]

Did you change the air filter or air intake?

The other sounds seems to be like a belt or fuel pump prime like. Weird. Never heard that before. Both are abnormal. Almost sounds like the car has a supercharger.

Have your tried removing the accessory belt to help isolate the problem?

 

[Dtrigg]

Sounds like gremlins or a tea pot to me.:biggrin:

 

[Joshs]

Did you change the air filter or air intake?

The other sounds seems to be like a belt or fuel pump prime like.

There's a DF intake scoop which has been there for 4+ years, and am currently running an OEM air filter. The only other mods are Comptech Headers, MagnaFlow exhaust, and a Comptech Powergrip 2 clutch.

-Josh

 

[Joshs]

Did you change the air filter or air intake?

The other sounds seems to be like a belt or fuel pump prime like. Weird. Never heard that before. Both are abnormal. Almost sounds like the car has a supercharger.

Have your tried removing the accessory belt to help isolate the problem?

I haven't tried anything yet other than driving around the block once to see if it magically disappeared.. It didn't. :wink:

After getting some ideas from the community I will try a few things if they're simple enough.

-Josh

 

[swerve2007]

check your belts for barbs/burrs/cuts- i've seen those producing similar whistling sounds.

 

[davidf]

DF scoop has been out 4 years?

 

[Joshs]

DF scoop has been out 4 years?

I ordered the scoop in August, 2005.. So closer to 3 and a half years.. I just meant that the scoop has been installed for a long time so it's not a new addition and unlikely to be related to my whistle problem (especially since the car isn't even moving).

-Josh

 

[AdvansCPAP]

I have the same noise and it stops after a few minutes of driving..I have no idea what it is. Try taking off the AC belt to see if it makes a difference.

 

[ChopsJazz]

I have never heard anything like that before. Does the car still run and idle smoothly? Are there any symptoms you can feel as well as hear?

It almost sounds like some kind of vacuum hose, but if one were disconnected you would surely feel its effects.

Perhaps you may have something in common with this thread?

 

[MANIACura]

I have the same noise and it stops after a few minutes of driving..I have no idea what it is. Try taking off the AC belt to see if it makes a difference.

+1. Taking off the A/C belt will help isolate or eliminate a few things. I've heard bad idler pulleys make all kinds of different annoying tones/whines. This will also eliminate the A/C compressor, clutch and belt.

 

[swerve2007]

since the noise goes away then it must be influenced by either temperature, pressure or lubrication. that would leave ac compressor, water pump and alternator and any possible failing bearings in the idlers. (i had a squeeling alternator before- bearing.)

 

[stevieray122854]

My money would be on an idler pulley bearing going bad. Had one on a Legend that made a very similar sound.

 

[Eclipsed]

There's a DF intake scoop which has been there for 4+ years, and am currently running an OEM air filter. The only other mods are Comptech Headers, MagnaFlow exhaust, and a Comptech Powergrip 2 clutch.

-Josh

You have pretty much the exact same setup as me. I had this same noise pop up last summer, turned out to be the tensioner pulley for the AC compressor(bearing was almost completely shot, would barely turn). I just cut the belt off since i don't use the ac anyhow. Cleared right up.

 

[KooLaid]

Removed the belt yet?

 

[Accel Junky]

I have the same sound. Almost sounds like straight cut gears but airy in nature. I really only get it in first gear. I have a stubby little HKS intake.

 

[Joshs]

Thanks for all the ideas!

I haven't noticed any performance changes since hearing the sound, but I only drove it slowly around the block once after first hearing it.

I just finished checking each vacuum interface and hose listed in the fuel and emissions section of the repair manual. The connections into the control box felt firm but I didn't pop the cover off and inspect further. All hoses feel nice and flexible and I don't see any signs of wear.

The A/C system isn't pressurized so the clutch shouldn't engage, but it seems possible that it could be the un-energized pulley.. the sound does seem to very slightly increase in pitch then disappear after even a slight rpm increase, as if whatever is causing it is duty cycled, but I still wouldn't rule out a friction problem.

Seems like the next thing to do would be to remove the belt around the idler pulley as you guys suggest. The A/C system is installed but has a leak somewhere, so cutting out the belt doesn't sound too bad. I'm not sure what the proper removal technique is, and I don't have a lift. I'll check the manual to see if it's possible to remove it non-destructively.

I'm pretty sure I'm familiar with the ABS chirp - or at least some chirping sound after startup sometimes which I attribute to the ABS pump. In my experience, that sound only happens shortly after startup or after an emergency stop, so I don't think that's it. I'll try to post a recording of that sound at some point in the future for reference.

The sound is quite loud, easily audible from inside the cabin. I think it only sounds at idle and not in gear, since when it gets any gas it rises in pitch slightly and goes away. I will have to doublecheck whether it sounds at minimal rpm in 1st.

Thanks again!

-Josh

 

[Joshs]

I just cut off the belt, and the noise is gone now! Yay! Although I guess that means I need a new pulley..

Thanks for the help - I was getting tired of taking the train to work! :wink:

-Josh

 

[AdvansCPAP]

No need to buy a new pulley for $80.00.

I fixed the problem the other day and it cost me $7.00 for a new AC tensioner pulley bearing from a local bearing shop.

NTN part number 6203LLBC3/2AS. If the shop doesn't have NTN, ask if they have an equivalent. The one I used wasn't NTN and worked fine. I got the info from the original poster below.

http://www.nsxprime.com/forums/showpost.php?p=580050&postcount=14

 

[KooLaid]

I just cut off the belt, and the noise is gone now! Yay! Although I guess that means I need a new pulley..

Thanks for the help - I was getting tired of taking the train to work! :wink:

-Josh

Or it could still be the alternator, pulley, or AC compressor. Or the belt is just acting funky.

It just means we're on the right track. That helps cut out alot of variables though.