Anyone have suggestions on what would cause a whining noise from a 4L80E in all forward gears and only when moving ? Once you hit 10mph it gets pretty loud, almost like an alternator whine coming from the speakers. I have checked trans and tcase fluid, disconnected radio and speakers, I can't seem to figure it out.

When driving I can put it in Neutral and the whine goes away instantly, once back in any forward gears it starts whining again.

 

Pump whine. How many miles on your transmission? Neutral takes the hydraulic load off of the pump eliminating the whine. My guess is that when your transmission is taken apart, clutch fiber material or worse will be found in the major hydraulic areas.

Rick

 

that's what I suspected. I rebuilt the trans a couple years ago, maybe 10k on it. I do remember the pump in this core was bad so I reused my original one, guess ill pull Trans when I pull tcase and inspect the pump.

 

Forgot to mention that I have a pressure gauge hooked up and it seemed to have good pressure still. Forget the readings but I don't recall seeing it drop below 120psi.

 

I thought that whine from the pump will be there in any position, PRND321.

 

Mine only whines in forward gears, it doesn't change pitch regardless of speed/rpm.

 

add 2 qts fluid and the noise may very well go away.
Yes, there is a load on the pump more in gear than in p/n
also, at speed, fluid is behaving similarly to how it would in an engine. Not all of it stays in the pan.

If adding doesn't fix, then the filter is likely stopped up