Squeak coming from my engine? Crappy Gas Mileage?

I have a '86 Nissan d21 pickup truck. Right now I am hearing a squeaking noise coming from the engine. Recently we had the timing belt changed, water pump, radiator hoses, etc. I also put in an amplifier to power my sub woofer. My dad told me that it is the bearing in the alternator, but I am not to sure. It only squeaks a little bit, like a small sounding squeak when the truck is cold. But when the truck warms up the sound is pretty much gone. It is still there but you can barely hear it over the sound of the engine. I also started to notice that my gas mileage is going to crap. I know that Nissan runs on a lot vacuum, so is it possible that there is a vacuum leak or something else. I also just changed the oil and oil filter. So please tell me what's wrong.
Squeak coming from my engine? Crappy Gas Mileage?
Go to your local autostore and pickup a %26quot;mechanics stethescope%26quot;. It looks like one of those listening things doctors use to hear you breathe. It's like $10. It's a good way to pin point the noise. Also helps locate dry lifters, exhaust leaks, etc.
Squeak coming from my engine? Crappy Gas Mileage?
could be the alternator....maybe the belt to the alternator....if you changed the belts..check the tension on the belts

use acne facial mask

drawing a circle