Let's see if someone has heard this before. I have a constant whistling sound that corresponds in volume to the RPM's of the engine. I have poked around looking for a vacuum leak, but I haven't found one. Does anybody have an idea?

 

Check the belt tensioner pulley. Mine makes a squeal from time to time and my dad's truck does it too.

 

This is definitely not the tensioner pulley. It sounds more like a real whistle. It is a real smooth sound. It's driving me nuts. I kept thinking it must be a vacuum leak except that the truck idles perfectly. Maybe it's a leak in a vaccum line after a valve. That might keep the idle normal? It gets louder as the rpms go up. I 'm going to get a piece of hose and search for the source today.

 

Let us know what you find out....I'm curious as to what exactly it is.

 

Hope the hose "stethoscope" told ya what it was. Good trick, and use it myself. Only way to localize what you're hearing under there. I found my squeal/whistle to be a leaking shaft seal on the EGR. A tomato soup can flattened out, cut, and placed strategically between the EGR and the plenum fixed that noise for the time being.

 

I have a 96 F-150 with the 302 and the same problem. The only difference
is that the only time I notice the whistle is in the winter when it is cold. Mine
will start when you are at a constant speed, increase as the RPMS go up, but
only to a certain point and then stop. I have tried everything to find it, but
no luck yet.

 

Check around the throttle body. My buddy had a thorttle body spacer that whistled like a turbocharger.

 

I think I have a ghost in the engine. I can't figure out where it's coming from. My mileage has gone back up, but the sound is still there. I think the increase came after my first full tank of gas after a fuel injector flush. I have a feeling it could even be something like the smog pump or a funny sound from the alternator. I guess I 'll just wait until it gets worse or something fails. I the meantime I'll keep tracking it and post something when I find it.

PS I'm going to check the throttle body. Could be, who knows?