My 1994 V6 4.0 2wd Ford Ranger has a transmission whine. I had left it parked for about 6months without driving it or even starting it. Im terrible, i know. Before it was parked, the transmission shifted and sounded perfect. It still shifts ok but now there is a whine. The first thing i did was check the fluid. The fluid level was fine but i drained it and refilled it with fresh fluid. The whine is still there. Its louder in the lower gears than the higher ones but it can still be heard. From what i've researched i've gathered that its most likely the input shaft bearing. Should i go ahead and pull the transmission? How hard is the bearing to replace?

 

Welcome to the forum

Manual or Automatic transmission?

If you coast down hill in Neutral does the whinning change as engine RPMs go down or stay the same i.e. wheel speed/differential RPMs

M5OD-R1(M5R1) was manual trans used from 1990 to 2012 in Rangers with 4.0l engines
It could have input bearing issues, not common but one of the things that could go wrong.
The whine should lessen in 4th gear if its an input bearing issue as 4th is not really a "gear" its 1:1 ratio just links input and output shafts, no counter shaft to drive

In Neutral, clutch pedal up, the input shaft speed will follow engine RPMs, so whine should change when coasting at same speed but with lower engine RPMs, and if you REV engine at that time then whine would change as well

Check differential fluid level