Odd problem, more annoying than anything. Each winter my 1998 4.0 liter ranger squeeks as the engine heats up in cold weather. During the summer, when the outdoor temperature increases, the squeek goes away. This has occured for the last 3 years. Over the years, I have replaced most equipment on the serpentine belt (alternator, water pump , power steering pump, belt tensioner, idle pully). Not the air conditioner compressor. The frequency of the squeek increases with rpm. Hence, not the trans. The squeek occurs with truck moving or still. Can't pinpoint the source of squeek. May be from the area of the crank shaft pulley. I'm thinking some metal may be contracted in the cold and other metal expanding as the engine heats up, causing a rub. The squeek sometimes goes away after about 30 minutes of travel, perhaps after all the metal heats up. Does anyone have this problem or have a suggestion?

 

Reads like an odd one.

Battery needs quite a charge up after starting in cold weather.
So alternator would be working harder, since you mentioned fan belt.

Fan clutch could be the issue, takes a good 10-15 minutes for rad to heat up and engage the fan clutch when it's cold out.

 

thanks. I did replace the fan clutch, but that did not stop the squeek.

 

When temp gets cold enough again to get a squeaking, before starting engine loosen fan belt and pull it off the crank pulley.
Start engine, see if squeak is there or not there, you can let cold engine run for 2 minutes without water pump.
That may help you ID if it is fan belt parts/pulleys or not.

My '94 doesn't have a Cam synchronizer(in the old distributor hole in the back top of the engine), but some '94 4.0l's did, these were known to start squeaking as bushing inside failed, more common on 3.0l but 4.0l also had that problem.

 

thanks. good idea taking off the belt. Just need a cold morning.