Howling / whining transfer case

[TerryD]

My LJR has 189k on the clock. At highway speeds under light load it really sings. I'm pretty sure it's the transfercase rear output. Tonight, while doing 65 on the interstate, I noticed if you leaned forward till you were at the steering wheel, you couldn't hear the whine.

My oldest daughter who was riding with me verified I am not crazy and the sound did mostly go away when you leaned forward.

Does this sound at all reasonable?

 

[hear]

When was the last time you checked the fluid?

 

[TerryD]

When was the last time you checked the fluid?

Changed it last year when I bought it and it's been bone dry but it's worth a look I guess.

 

[TerryD]

Fluid level was about 3/16 below the fill hole with the nose tipped down in my driveway.

Rear output sounds OK. I didn't hear anything in spinning it in neutral with the drive shaft off that makes me suspect of it.

I topped it off with Lucas to see if the heavier oil would change the tone or anything but it didn't. Now I'm suspect of the transmission output.

It whines in all the forward gear and only at light throttle. Full coast or full throttle, the whine lessens or goes away.

 

[Chris]

Fluid level was about 3/16 below the fill hole with the nose tipped down in my driveway.

Rear output sounds OK. I didn't hear anything in spinning it in neutral with the drive shaft off that makes me suspect of it.

I topped it off with Lucas to see if the heavier oil would change the tone or anything but it didn't. Now I'm suspect of the transmission output.

It whines in all the forward gear and only at light throttle. Full coast or full throttle, the whine lessens or goes away.

Given that the noise is present during light throttle and diminishes at full throttle or coasting, it could very well be related to either the transfer case or the transmission output.

Since you mentioned that the transfer case rear output sounded fine when you spun it in neutral, it's worth closely examining the transmission output as the next step. Sounds like it could potentially be a bad bearing.

 

[TJuser]

Disconnect your rear driveshaft and drive in 4wd. What you're describing to me sounded like my diff before it went. Under throttle, couldn't tell. Light load in 4th or 5th gear, it howled like a mofo. It sounded like it was coming from the transmission but the sound travels thru the driveshaft.

 

[TerryD]

Disconnect your rear driveshaft and drive in 4wd. What you're describing to me sounded like my diff before it went. Under throttle, couldn't tell. Light load in 4th or 5th gear, it howled like a mofo. It sounded like it was coming from the transmission but the sound travels thru the driveshaft.

I'm going to check that tonight but I regeared it less than a year ago. It's possible the pinion preload was too tight I guess....

 

[TJuser]

I'm going to check that tonight but I regeared it less than a year ago. It's possible the pinion preload was too tight I guess....

Yeah ok. I just figure it's worth it to do that before digging into anything else too deep

 

[TerryD]

Replaced the pinion bearings and set the gear set up better and no change in the howling.

It's really got to be the t-case rear output under load, right?