Tranny Whine

[BlazeGM4]

It's been a couple of months now since i had my tranny serviced and since that time i've noticed that i get a whine when i drive highway speeds at little throttle. The sound resonates and gets quite loud but stops right away when i let off the throttle.
The only things that were done were tranny flush and filter, levels are ok.
Any ideas?
Come to think of it the pitch increases and decreases with vehicle speed so it might be somewhere else in the drivetrain too.

[torque454]

I've seen rear axles do that. Might check the oil level in it.

[BlazeGM4]

This isn't sounding good, i know my front diff leaks like a sieve from input and output seals. Haven't checked the level in a while, i put all new seals in the rear diff. and no leaks are seen.

[grancito]

It is most likely diff whine, if it whines at low speed, like 30 mph, look at replacing the pinion bearing. If the whine starts at 50 or 60 mph it is gear noise. You may be able to make it quiet by increasing the gear back-lash. Change the spacers to the outside of the carrier bearings, so that the ring gear moves away from the pinion by about a 1/16 inch.

[BlazeGM4]

The whine starts anywhere between 30mph and 80mph and only dows it when there's load on the drivetrain, once i let off the throttle it stops right away. It's odd that this came about so suddenly, and right after i had the tranny serviced. The sound, to me, seems to be coming from front to mid vehicle. Is it possible it's the front diff? It wouldn't hurt to re-check all fluid levels.

[grancito]

It won't be the front diff unless 4wd is engaged. Check to see if the front drive shart is turning, if so the drive chain whines, but not just with power on, so that is unlikely. Is the torque converter locking, if not and the new filter seal is leaking air, the converter could make the noise. A few things to check.

[962500]

you might want to check your hanger bearing they can produce a whine at the center of the truck.

[BlazeGM4]

Torque converter does lock up and hanger bearing? Is that the same as a steady bearing? If so my truck doesn't have one.

[grancito]

Blazers don't have a hanger bearing because they are short and don't have a split drive shaft. The whine is a mystery to me, check the stearing pump oil level, but they whine when you turn the wheel. Was the tranny filter changed before the whine started, could still be sucking air and therefore pump noise. Just trying to suggest some simple possibilities.

[BlazeGM4]

The tranny filter was changed before the whine started. Also they used a machine with it's own pump to flush the oil. The one thing i noticed right away was the shift points changed and were firmer, this oil was dark and i dont know if it was changed since the factory :/ The whine does seem to come from the tranny area beneith the floorboard. The diff and t-case fluids were changed a few months prior to the tranny, no noises were noticed then, however, i'm being distracted by my loss of power and engine miss at WOT now :( . For once i'd just like to get ahead, 285,000kms, i know all injector nossles and injection pump replacement are overdue. Then there's the occasional code 35 & 36... lol

[BlazeGM4]

Should've updated this a while ago. Turns out when I replaced the rear pinion seal I didn't torque the nut properly and started to wear the bearings. I replaced them and no more whine, while I had everything apart I put in a new Auburn limited slip in (which I picked up an actual locker for the extra $200) The OEM govlock diff grenaded.