Rebuilt my motor, motor's running great but I'm hearing a light grinding sound from the Torque converter area. Initially thought it was from the gasket between the transmission and engine rubbing on the TC, but pulled off the cover and it is not touching, no rub marks either. The noise is constant with RPM's, and goes away under load. I can always hear it when coasting or idling, but disappears completely when accelerating. Before I installed the TC I spilled a bit of fluid, maybe ~10 mL, could this be it? ATF level is fine as well. Any ideas to what this could be?

 

Interested in this one -- I've been hearing the same kind of noise.

Only when coasting really. Do you here it just sitting or when you are moving?

I haven't done anything to my engine -- does it sound kind of lug a chugging-grinding noise?

I would also check pulleys -- anything that normally moves... I haven't checked mine yet. I know how some noises can bounce up off the pavement and sound like they are coming from somewhere else, though.

 

I can hear it when it is in park or neutral sitting still as well as coasting.
Sounds almost like metal on metal rubbing.
all my pulleys spun well when the motor was pulled, same as the crank. Only one tough to spin was the alternator, how hard should they be to spin? I had to try quite hard to move the alternator at all by hand. It does work fine tho far as I know

 

the alternator is hard to spin because of the brushes making friction....its wound up pretty tight!

and I dunno on the TC problem, OldirtyJohn is the transmission expert on this board

 

As long as the alternator spins quietly you are good.

If it makes any noise at all I would be concerned.

Sounds like there is another problem here, though, than pulleys.

 

Have you gotten under the truck while it is running and actually verified thats where the sound is coming from or are you relying on echos from under the truck and engine bay?

 

I got under the truck with the structural cover removed

 

If the alternater was hard to turn i would guess that is the source of your noise. pull the belt and fire up the engine to see if the noise is still there or not.

 

Might get a stethescope (available at WalGreens) and use it to try to pinpoint the source of the noise. I'd start with the alternator just because it was a little hard to turn. Could be normal brush friction, or a bearing going.

Don't get the tube from the 'scope caught in the belt!

 

When you re-built your engine did you replace the bearings? If your hearing metal on metal sound around that area I would be listening close to the oil pan area.