Whine at 70mph....

[project_x]

2 days ago, I noticed a loud whine while under load at 70mph @2200rpm. If I let off the gas, it quiets down.
I may have also had a slip in my transmission... Very minor.

It sounds like it is coming from the front... But that is just a guess (last week I had a dragging caliper, that we thought was in the front and it was actually in the rear). I checked front diff fluid, trans fluid,...will check the belts and pulleys.

I leaning towards the transmission... But should I look somewhere elsefirst?

Also, this is a new to me Suburban, I've put on 10-15k miles... It has about 170k mikes and I don't know what has been done with the transmission (but the fluid looks ok).

Would it be worth doing a fluid change, drop the pan and filter change? I was planning on getting to this in the spring.

 

[Marky Dissod]

People generally don't change their ATF often enough, so even if it turns out to not be the transmission, yes it'd be worth it, so change it sooner rather than later.

What year is your bubba? Is it RWD or 4WD or AWD?

I'd also check wheel bearings, axle bearings, and axle / axles.

You said if you let off the gas it quiets down.
What happens if you gas it more, enough to call for a downshift? Change the ATF first though.

 

[project_x]

2005 Suburban 4x4 LT with 5.3L and 4L60E


I agree that changing the transmission fluid is worth doing often (which most neglect)... I was more thinking would dirty fluid/clogged filter produce a whine? or is it more likely to be a bad trans pump or something else in the transmission.

 

[S33k3r]

How many miles do you have on your rig?

 

[Joseph Garcia]

Get the truck up on a lift at a local shop, raise the wheels off the lift base, and set it in drive with the wheels turning. Then, with a stethoscope, search for the whine.

This is what I did in this situation, and the issue was a failing front differential. Swapped in a low mileage used one, and the whine went away.

 

[Marky Dissod]

I agree that changing the transmission fluid is worth doing often (which most neglect).
I was more thinking would dirty fluid / clogged filter produce a whine?
Or is it more likely to be a bad trans pump or something else in the transmission.

Glad we agree on changing ATF more often than GM says.
Don't know if dirty fluid / clogged filter would produce a whine, but if it did ...
As for a bad trans pump or something else in the transmission, if either has not gone irrevocably bad yet, changing the ATF might still be of some help.

All that said, I am afraid Joe may be right - might be your front differential.

 

[project_x]

I poked around with the front end in the air yesterday,...pretty cold. It looks like everything is spinning without drag.

What would you see if the front differential actuator was stuck engaged?