F- 150 rearend hum from towing ?

[Mark Gross]

O.K.My 1997 F-150 4x4 ext. cab 8 ft. bed has a problem that is driving me banana's. I think it happened several weeks ago ,I was pulling the boat out of the water and had the emergency brake on (something I otherwise never use)and yes I forgot to release it. I drove a couple of miles like that until I realized it was on.I didn't think much about it until a couple of days later when I started to hear a high pitch yum from the rear Iif I let up on the gas just a little bit it goes away.already had the rear brakes checked out there fine.A ny idea's on what might be wrong? anyone ever have a simular experiance.

 

[Rob LaMoy]

Bearings maybe, or perhaps the differential. If it's happening with gas and not without then it's associated to torque. When the pressure is off it stops so it could be the gears. One thing is for sure, if you were able to drive away with the e brake on, it wasn't working in the first place. Do you have posi in the rear end. My Dodge did that, it was the clutch in the posi, needed to add friction additive.

 

[Rob LaMoy]

NO! Don't put it in if you don't have posi! It's only for posi, so the clutch can grab even though it's submersed in gear oil. Have you checked the lube though to be sure you don't have any water in there. I had to reseal mine once because the cover had rusted enough that it allowed water in while backing the trailer in. But be sure that's where it's coming from first. Could be as simple as a u-joint on the drive shaft has dried up. They're only about $10 and take a few minutes to replace, unless you have a carrier bearing, dumbest design I have ever seen! Anyway, keep looking and positively diagnose the problem first before making any corrections that may not be needed.

 

[Jason _G]

I would check the gear oil... Sounds like a whining gear case to me...

 

[JEFF WHITE]

we had a expedition with the wining/vibration deal from 1,200 miles on.1st thing to do is check the gear oil,ig it has never been changed,pull the cover and change it.use synthetic 85w90,or whatever the book calls for.while your in there check the bearings and seals.pull the drums and check the wheel seals and bearings.with no drums on the hubs spin them and feel for roughness,if there is,then its a wheel bearing going south.to change them you have to pull the rear cover to get to the c clip to pull the axles.change both sides with the seals.check the u jo9ints also,check for dryness,rust streaks round the caps,visible look at the inside by the cross if they look questionable,change them,they are cheap,less than $10/piece.get the greasable type.



when you refill the rear,tip the axle away from the fill plug slightly to get that little extra fluid in them. ford 9" rears were noted for blowing pinion bearings out due to lack of oil,also the extra will make sure the wheel bearings are well lubed.the rear in your truck is based on the 9",so the extra oil wont hurt it.if it is a posi,add the 2 oz or whatever they call for of the friction modifier.

 

[Brian Allen]

You need to service the rear diff, and see how much metal is in the oil, The noise you describe is common when the pinion bearings fail.Have you had any work done to vehicle prior to this noise I.E pinion seal replaced?

Brian Allen ( ford tech )

 

[Mark Gross]

The only thing I've had done is the oil changed in the rear-end.

Rob I didn't do anything to it yet,But thanks for telling me.

I think I 'll go ahead and change out the oil and see whats there first.

When I had it up on the rack having the brakes checked out there seemed to be a lot of play when you turned the wheel and the drive shaft movement.

 

[scott lewis]

My 150 's hum came from the outer axle bearings.

I have been told they will leak when backing trailers into the water. Allowing water in check diff oil for water / milk shake looking oil.