what could be wrong when a belt squeaks (most likely a timing belt) after i start up and when sometimes i downshift?

my car is a 1994 Honda Civic DX it has a 165xxx miles.

 

Typically when a belt squeaks it is the belt slipping on the pulley. The most common cause of this is a glaze on the belt. Over time the belt will become glazed or if it is loose it will do so at a much faster rate. Simple replacing the belt should fix this problem. A timing belt has teeth that lock the belt and timing gear which would make it very unlikely to be your culprit. I would look closely at you’re A/C belt then the ALT belt.

 

It is deffinately not your timming belt. If your timming belt slips you will know it and not by squeks. It will run badly if only maybe one or two teeth. Much more than that your engine will be screwed. You will be replacing much more than a belt.

 

possible water pump wear

 

ahh it's almost certainly your alternator belt....your timing belt can't possibly squeek it has teeth on it and if it slips then yer car don't work.... yer alternator has 2 bolts on it, one to hold it onto the engine and one for adjustment (it is on a long slider...) loosen the bolt on the slider, use a pry bar and put some torque on the alternator... push it away from the motor, so the belt pulls tighter... tighten it and squeak no more.

 

Your adjustment bolt has a lock screw on it to keep it from moving so make sure you loosen that first.

 

Timing belts dont squeak...They slip and all goes to hell so its not that...Check your alternator belt...Ill put money on that one...Or if you cant tell put a voltage gauge in your car and if the needle jumps back and forth when it squeaks that is defenitly your problem...good luck