Hey guys,

My truck makes a horrific screeching sound when it's loaded or pulling a small trailer (2000lbs) up hill. I discovered last night while I had it in drive, if I hold the brake and give it a little gas (like if you were trying to do a burnout) it will make the screeching noise as well. It won't break the rear wheels loose either, which makes me think it's down on power or the transmission is slipping.

My first thought is the transmission, but some searches on this forum describe U-joints or the carrier bearing as possibilities. The previous owner told me he replaced a U-joint just before I bought it, so I'm not ruling that out at all. Any ideas?

My truck specs:
1995 351 E40D 4x4 (manual transfer case & hubs), extended cab eddie bauer. 158k.

 

Not the ujoints.

If it were the bearing, that bearing would be HOT right after you hear the screech.

I think this could be the torque converter clutch or something else internal.

Start saving up.

 

If you get the screech when the truck is not moving, it's not the carrier bearing or u-joints etc.

Can you have someone stand next to the truck when you duplicate this, if the sound is from the front maybe it's a belt tensioner or idler pulley (not uncommon) or even A/C clutch (is the air on?).

Good luck,
- Jeff

 

I usually drive around with the air off, and it does have at least one idler pulley squealing when it's cold.

I'm pretty sure this is something transmission related. I guess I'll pull the codes on it and see if anything is there.

 

I took the liberty of checking both harnesses that run to the transmission. The one on the passenger side had oil in it. I cleaned off the connector on the harness and on the trans with electronic cleaner, then put on a bit of dielectric grease. I also did the same for the connector on the MLPS (or neutral safety switch as some call it).

I go for a test drive, and I've lost first and OD. Damnit!

This appears to be classic MLPS going bad symptoms, so I picked up a new one from napa. Installed it, and the truck has never ran better! First and OD is back, plus my original problem with the squealing seems to be better, it has more power and it will lay some rubber now in first gear. Rock!

I'll update this thread if anything else crops up or the issues return.