2001 2.5L 5-speed manual.

My truck has started squealing, in the mornings and after work (on days below 50°F), when I depress the clutch pedal to shift gears. It sounds sort of like a loose belt. Engine oil level is good, but the pressure switch/sensor only works after the truck has warmed up. I'm not sure what else to troubleshoot as this is my first manual transmission that I've needed to service.

Any thoughts on what to check?

 

Like this?

 

No, nothing like that. Honestly it sounds like a squealing fan belt. It's going to be hard to get a recording of it, as it only happens while I'm shifting gears.

 

Whelp... engine rpms are up between shifts and pullys and belts usually squeal at higher rpm, I'd say that when the belts are under the forces of acceleration the tensioner holds tight and the squeal quits. Possibly the rapid loss of tension between shifts is allowing the belt enough time to come loose until the tensioner catches back up.

check the retraction rate and spring strength on your belt tensioner, does it snap back fast or is it slow?

if it's good then

spray each pully (on the center bearing) 1 by 1 with WD40 and drive it, listen for the squeal, when you don't get a squeal, the last pully you sprayed is your bad pully.

as for your pressure switch, it's on the side of the block on the drivers side, right at the back near the corner. Just about directly next to the last intake manifold hole. There is a wire on it, go ahead and make sure it's attached well. Metal expands under heat and is probably only contacting after its hot.