1996 4runner 6cyl auto. Whining noise when put into reverse or drive. Does not happen in park or neutral. As you accelerate, you hear the whine as it goes through the gears and seems to quiet down some once up to speed but doesn't go away completely. It does not seem to effect performance, the truck runs fine. Issue seems to be getting louder as time goes on. Any suggestions? Thanks.

 

I had an whine that sounded like an electric motor on my 4Runner and it turned out to be my alternator. I got the alternator replaced and now the noise is gone.

 

Is the whine with rpm or wheel speed? If it's wheel speed, it could be a wheel bearing or your driveline needs some grease.

 

The whine is with RPM but only when driving. If you rev it in park or neutral, there is no whine.

 

the noise seems to be coming from low in the engine bay near the firewall.

 

Transmission maybe? I've not heard of that whine before. Check your tranny fluid level and make sure it doesn't smell burnt. Someone else might be able to help.

 

Took it to the dealer and they wanted to replace the transmission at the small price of $3200. Figured I should get a second opinion from a transmission specialist. Tranny guy replaced filter and fluid hoping it would resolve the issue but it didn't. Inspection showed very little debris in pan so he was leaning toward a bad torque converter, but wasn't positive. Wanted $1600 to replace torque converter with the chance it still may not be fixed. Since the truck is reaching 13 years old and 214k miles, I would hate to put that kind of money in it. Anybody have any thoughts or suggestions ?

 

My 2000 runner 3RZ has a similar symptom, and the alternator is my #1 suspect...

 

Whats the best trouble shooting method to determine if it's the alternator or not? Take the belt off?