When my truck (4.6) is idleing, on the outside I can hear a really high pitch whistle coming from under the hood somewhere. Does anyone have any ideas?

 

My 4.6 does the same thing. I think its the air intake. There is a duct that runs through the fender. I think its just tunnel noise.

 

Is there a way to get rid of it? Do you have a K&N filter?

 

Hey 97 - sometimes this high pitch sound is caused by a vaccuum leak. You can raise the hood with engine running and probably locate the leak. If it is a leak it will be in one of the hoses or lines somewhere. You can run your hand along each hose and perhaps find it. Or you can get a spray of water and spray each hose and you might see bubbles or hear the sound change.

You can wiggle the hoses and that might make the noise change pitch.

Let us know what you find.

 

Id leave it alone!!! If it sounds like ya got a blower under da hood, you'll intimidate your fellow motorists!!

 

I dont have a K&N, but im gettin' one on Monday. We'll see what happens...

 

I agree. I have k&n fipk and it makes that noise. I plan on getting a s/c someday then it won't sound like I have one, I will have one! It might be a vacuum leak.

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1997 XLT Teal 4.6L Flareside 4x4 ORP. Automatic, Reg. cab, 3.55LS, tinted windows, bug deflector, Dual exhaust, K&N Generation 2 air filter, BullDog keyless entry/remote start, Modern 16" wheels, bedliner, Covercraft tonneau cover, White faced gauges, electronic shift on the fly, Clarion ADX5655z Double Din Cassette & CD, 4 Pioneer TS-A6865 speakers and superchip.

Future mods: Supercharger, headers, NOS, tranny upgrade(heavy duty gears, clutch packs, etc.), performance torque converter, composite driveshaft, bore cylinders 30 over, new pistons, crank, and rods, get performance heads or port the ones I have, gauges for the a-pillar, new L if they still make them and I like the way it looks, and a Z06 Vette or BMW Z3.




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Which vaccum lines do I check? I can't really tell which ones are vaccum lines. Also - It seems to have just started. At first I thought it was from the K&N (which I just got) but it isn't

 

I also have a high pitched whistle...but it makes more of a whirring sound than a whistle. The pitch increases as the rpms increase. Seems like its coming from the back of the engine. I have no idea what it might be. Just hoping its not a bad bearing deep inside the engine or transmission.

Any thoughs on the matter?