Howl In Drive Train When Foot Is Off The Gas

[0luke1]

There's a couple of threads on similar problems with no real solutions.

I hear a howl if take my foot off the accelerator between 45 and 55 MPH. You can hear it over the noise of the radio.

The howl goes away if you re-apply the accelerator and get torque back on the drivetrain.

My truck has less than 300 miles on it, 4.10 gears, auto, z71, no cladding.

Anyone figure this one out?

 

[endeavorc]

It's the rear diff gears. Depending on the wear pattern on the gears (won't know until you do a diff service or you have the dealer open the diff and have them checked) it is considered normal. Mine went in at just under 12K with the noise, the gear wear pattern is in the center of the gears which is good. If you have a wear pattern on the outside or inside edge you need to get them replaced.

PS. At 300 miles they might just be setting in to a wear pattern. I would still let the dealer know though.

 

[0luke1]

I've owned a lot of four wheel drive vehicles over the last 10 years, a 86 CJ 7 (with over 100K and 31" tires, a great truck that I drove until it was too rusty to be safe), 99 Cherokee, 95 Grand Cherokee (not a great truck), 92 Jimmy, 99 Ford F350 (V 10 - a great motor) and an 01 Ford F150 (not a great truck).

None of them had a gear howl like this.

It's distracting when you drive.

 

[midlifecrisis]

I hear a noise when I let off the accelerator, but it is not gear howl. It seems to be coming from the engine compartment, and it is higher pitched, almost like air going through tube or something. The instant I tap the gas pedal again, it disappears.

 

[spyder63]

There's a new drive shaft out that has a harmonic balancer on the aft end. the balancer looks like the one that is on the engine crank shaft. My dealer has one on order for me now. This is suppose to take care of the whine/howl in the rearends.