292 f-100 3 on tree. Got this high pitched whine. Already eliminated the alt, and water pump as a source. Also checked the dist. Sound seems to be comming from the back of the engine. This is my daily driver and she still runs and drives ok,, but this sound started about 3 weeks ago and its driving me crazy. Any ideas?

 

Does it sound the same with the clutch dis-engaged, the trans in gear, and the vehicle not moving? Does the sound change character or loudness with increases of engine rpm?

Even if the sound is "metallic", you could have a vacuum leak whistle. Use a hardwood stick about two feet long to transmit the sound from the source to your ear. I press one end of the stick against a suspect component (generator) and the other end against my skull behind my ear. Another improvised stethescope is to use a two-foot length of hose - it will be better for looking for whistles.

 

fogot to add the part about the trans, makes no difference with clutch in or out or with trans in gear or out. does seem to change along with engine RPM.

 

Going down the road at a fixed speed, does the sound change with throttle position? If it does, the odds are it is in the intake system (vacuum leak, carb noises, . . .).

 

im leaning towards vacuum as well

 

I had a starter bendix go bad and make a sound like that. You can check it by droping your clutch cover (engine off wheels blocked) and look at the starter bendix to see if the bendix gear is still engaged into the fly wheel. It should be kicked back and not touching the flywheel.

 

It's probably the neighbors' cat.