Karl O.

Bone stock '01 S2000 with 49,1xx miles. Makes a slight sqealing noise at partial throttle between (approximately) 3000 and 3500 RPM only. Does not produce the noise anywhere else but that RPM range. Lift off the throttle, it stops. I don't hear it when at full throttle, but that could be because the engine is louder at full throttle.
Pretty sure it's coming from the front of the car.

Car works perfectly. No other problems with the engine, ever. The only maintenance that has been done to the engine other than changing the oil and the air filter was the spark plug TSB.

It's been making this noise for at least six months. Very faint at first, even now I can only hear it with the top down and the stereo at low volume.

I originally thought it was the front brake wear indicators, but the dealer checked them in 11/04 and again last week and said the pads were fine. Dealer claims that they can't hear the noise, the car is in "tip top shape" which is true, you could eat off any part of the engine compartment, I even use a shop-vac under the hood. Mechanic said I was hearing "VTEC noises." At 3000 RPM.

My wife hears the noise too so I know I'm not crazy. Well, at least not about THIS particular noise.

The only similar noise problem I've ever had was when the A/C compressor on my '90 Lincoln Town Car croaked. When I turned on the A/C it made the same kind of sound, except 10X louder.

Any suggestions are welcome. My only other current plan is to just wait until the noise gets louder or until something breaks. Not my favorite plan of action.

ImportSport

Does the sound go away when you apply a very slight amount of pressure to the clutch? Very slight just enough to tense the system but not take it out of gear.

Karl O.

Don't know but I will check at lunch. Thanks for your reply.

SIIK2NR

Sounds like belts need to be changed or tightened.

Open the hood and rev the engine a little to see if you can identify which belt it its...

xviper

My first guess would be intake whistle, which this car seems to exhibit on quite a lot of examples. This noise is generally amplified when a CAI like the AEM is installed but many have reported this with the OEM intake. To test this out, take out the filter, put the lid back on and go for a very short drive to try to duplicate the sound. Do this only on a day when there is low dust and debris floating around. Clean out the airbox first so you don't suck any crap into the engine. Go only as high as the rpm that would duplicate this.
It could be that your filter is at a stage where the air goes through it just so to start this noise.

Next, I would suspect those things stuck onto the front of the engine that turn - belt tensioner, alternator pulley, water pump pulley, A/C compressor pulley. Wouldn't hurt to squirt a little silicone spray into the bearing area of each of these.
ps. Serpentine belts generally don't get "lubed".

SIIK2NR

Good point... edited..

Karl O.

Good suggestions, guys, thanks. I may buy a new OEM filter today and try it, it's been 20k miles so I don't mind changing it. I cleaned out the airbox on Sunday and the air filter was looking a little dirty.

I didn't think it was the air filter because I had just about every conceivable sort of aftermarket intake on my old Civic and I'm familiar with annoying intake noises, this is different. Never know, though, S2000 is a strange vehicle.

Think I'll have my wife rev the engine while I check out the engine compartment. If the car refuses to make the noise in neutral, then that would tend to point towards the clutch or trans as ImportSport alluded. Conversely, if the car does make the noise in neutral then it might point to something non-trans related.

I did try playing with the clutch while driving but for some reason the car wasn't making the noise much. Both times I got the car in the right position to check I tapped the clutch pedal a little too hard and the revs shot up past 3500 RPM. This car has one responsive throttle!

ImportSport

It's so hard to play the noise game online but depending on the conditions it could be the throwout bearing. If you can stop the sqeak with a very slight touch of the clutch pedal this may help point you in that direction.

I hope it's just an intake whistle though

Karl O.

Well I changed the air filter and it still makes the noise- which does not rule out intake noise, it just means I have a clean air filter. Think I'm back to taking a short drive around the block without the air filter.

Heh-heh, maybe it does sound like intake noise- all the kids will think I'm a cool guy that has a CAI!

If the throwout bearing was heading downhill, would there be any other symptoms? How long would it make the noise before it croaked? What will happen when it finally gives up the ghost?

If it's just one of the accessories the noise will eventually get loud enough for the dealer to diagnose and I will be left trying to make HondaCare pay for the repair.

Billman250

Sad to say....I know the EXACT noise you are descirbing, but have not found the source as of yet. Sounds like a qiuck air whisle. Never continued noise, right? I have tried swapping airbox lids, and filters, no good. I have a few cars with this noise and will have an answer eventually.....

Here's a test you can do, which I just thought of but have not tried yet.

Drive the car without the serpentine belt installed, to isolate all moving pullies up front. HOWEVER, Make this entire road test no more than one minute long, as the water pump and alternator will not be operating. I'd advise doing it while the engine is cold, this will give you plenty of time out of the danger zone