Hi all,
My 2001 F250 5.4 has started to make a screeching sound. It only happens when it is in gear (auto) moving forwards or in reverse, and increases in pitch relative to engine speed rather than road speed, and is much more noticeable under mild to moderate acceleration.
Maybe I actually mean transmission input speed?
When simply maintaining road speed, it is almost silent. Anyway, if I drop it into neutral while driving, the sound stops, and starts again when I put it back into gear.
From the drivers seat and with the windows closed, it sounds as though it is coming from the engine bay at steering column height, although this is really tough to gauge while actually looking where I am going With windows open, it comes from both sides of the vehicle.

1st thought is tranny......
2nd thought is a water pump bearing, although there are no apparent cooling problems or leaks.
3rd thought is the alternator bearing, although there are no charging problems.
I say alternator because I recently changed the serpentine belt and noticed that the alternator made a very faint screech-like sound when spun without the belt on it. The main screech was there before I changed the belt. Maybe it gets really loud under load?

So I'm kinda scratching my bean and wondering what expensive piece of mechanics I'm going to shell out for next. If it's #2 or #3, I can do those myself, but if it's #1.... it likely means more money than I have to spare.

I did wonder about removing the serpentine belt and driving a very short distance (end of the driveway and back) to see if I can remove the pulleys, tensioner or other belt driven parts from the equation. Maybe this is not such a smart idea.

Does anyone have any ideas please? I'm somewhat at a loss right now.

Many thanks
Onesprint

 

You could try removing your serpentine belt and drive it just a little distance. See if the sound goes away. That might eliminate a long list of possibilities.

 

I think it MUST be a coincidence, but I implemented the fix in this post from Mark Kovalsky since I was also having trouble engaging the correct gear, and now the screech is gone.

https://www.ford-trucks.com/forums/1...l#post13199300

Is it possible that this was somehow holding up the shift mechanism and/or transmission and making the screech?

Pahhhhh!