Humming noise from drive train

[RVN DAVE]

I noticied that when I get my truck up to speed
it will start making a humming noise. It does not
do it when you are speeding up or slowing down.
if you're driving at 50mph it will make the humming
if you let off the gas slightly it will stop and when
you press the gas again it will start again...

It's a sound similar to that which a truck with oversized
tires makes when driving down on pavement...

Any ideas?

2002 S-10 crew cab, 4.3 V6 4x4

[troy1]

humm if its like my dodge its the rear end just the gear pattern wear making noise. This should not be very loud if it is you might have worse problems

[RVN DAVE]

Originally Posted by troy1

humm if its like my dodge its the rear end just the gear pattern wear making noise. This should not be very loud if it is you might have worse problems

Correct, It's not a loud noise at all...It really only seems to do it at an idle speed of 40-50mph...I wish I could say where the sound is coming from but there is really no indication of any particular side of the truck or if it's the front or the back....there is NO clunking, vibrating or hard shifting. Could
i possibly just need to flush the transmission? I'm a little worried/nervous
because I tow a trailer that weighs in the upwards of 78% of my trucks towing
capibility.

[mrmikey]

2001 S-10, 110K, 2WD 4.3 Auto
Other than what was said re the differental
Don't know what would be different on a 4WD other than the obvious of course.
Right after I bought mine the u-joint's went south. After installing new joints as well as cups the vibration was unreal. Eneded up getting both shafts balanced but still wasn't right ( the cursed double u-joint setup). I don't think I would call it a vibration tho, more like a thrumming sound.
On the advise of the driveline shop I got them to make a shaft with single joints which cured the vibration.....Mike

[eti engineer]

Do you have the driveshaft with the double cardan joints (look like double u-joints)? If you do, then most likely the ball and socket assembly has worn and is allowing the u-joints to whip and be out of alignment. If you don't have a lot of upper arm strength, a vice with a 6" opening, a source of heat to melt the plastic retainers for the factory installed u-joints, and a lot of patience and mechanical inclination, I would not attempt this.

Do what I did after I replaced my first one and the second one went a year later. Go to a driveline shop with both pieces of your driveshaft and have them build you a new rear section and balance the pieces as a whole. 300 dollars and I elminated one of Chevy's big mistakes on the S-10.

Let me know if this is it. The u-joints will feel fine on inspection. It is the ball and socket assembly that keeps them in line that goes bad. Does it sound like a prop airplane at certain speeds?? If so, I am sure this is it.

later...

eti engineer