I've got a minor noise and I'm wondering if it's "normal" or "something to be concerned about."

It's on my 2002 4Runner (auto tranny). When I go into 4WD, I get a whirring sort of noise. The noise only shows up when I apply the throttle and stops when I coast. It's not very loud, but it's there. I changed the transfer case and front differential fluid just this past fall.

If I listen very closely I think I can hear the whirring when I'm in 2WD, but it's very very faint. I'm thinking that in 4WD I'm just hearing the same sound, but amplified by the 4WD mating up driveline parts and transmitting the noise. If I had to guess I'd say it's coming from the forward part of the driveline, so maybe it's gear noise from the front differential.

Any insight is appreciated.

MadCityRich
'02 4Runner

 

get a stethoscope. Put the truck on jackstands. Don't touch any moving bits! Listen to the front diff, xfer, and rear diff with the vehicle running in gear.

 

Mine "whirrs" in 4WD... always has. Matter of face, besides the 01 F150 I had once, all of my 4WD vehicles have made more noise in 4WD. Same with all of my buddies.

Unless it is a noise that is loud enough to warrant worrying, then don't sweat it brother. It is the added spinning of the gears in your transfer case I think.

My .02

James

 

My 04 Tacoma (basically the same drivetrain, including the autobox) makes the same noise. Some gear noise or something that only comes up when in 4WD.

 

I deveolped a whine in my front end. Got louder when in 4wd. Turns out I had gotten water in there from a low water crossing. Drained it and refilled the front diff and it has been smooth and quiet since.

 

something else that can cause a whir from the vehicle. power steering fluid getting thickerer over time

power steering fluid, when old, can cause the pump to whir. I found this out as I popped my lines to do some other work, then put new ATF fluid in the power steering to fill it back up. a whirr that I was hearing now and then went away.