Just how whiny is the NSG370 / 231 transfer case combo?

Geok

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Jun 14, 2022
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South Louisiana
Changed transmission fluid (NSG370) with Redline MTL. Lots of metallic material on the magnetic plug :(. Not sure how much is appropriate. The whole plug was covered on inner surface. It's a 2006 with 65K.

Changed transfer case fluid. Looked like strawberry milkshake. Not sure if it got water somehow (I presume it did), but I've never done any fording - so PO? Tried finding/tracing the vent to see if damaged.. Looks like it terminates under hood somewhere and is zip tied to refrigerant lines?

I was worried about a whine I heard and I had no idea when the last time either were changed (if ever). The "whine" is there while driving and goes away when taken out of gear. I know there is some whine, but I have no other Jeep TJ perspective to know if it's within acceptable limits. I'm hoping there isn't a bearing out/going bad.
 
Changed transmission fluid (NSG370) with Redline MTL. Lots of metallic material on the magnetic plug :(. Not sure how much is appropriate. The whole plug was covered on inner surface. It's a 2006 with 65K.

Changed transfer case fluid. Looked like strawberry milkshake. Not sure if it got water somehow (I presume it did), but I've never done any fording - so PO? Tried finding/tracing the vent to see if damaged.. Looks like it terminates under hood somewhere and is zip tied to refrigerant lines?

I was worried about a whine I heard and I had no idea when the last time either were changed (if ever). The "whine" is there while driving and goes away when taken out of gear. I know there is some whine, but I have no other Jeep TJ perspective to know if it's within acceptable limits. I'm hoping there isn't a bearing out/going bad.

Post a YouTube video and link it here.
 
Done with iPhone while driving in my neighborhood. You can hear for a couple of seconds at the 30 sec mark and later around 1:15 on.
Sorry, not the best sound quality.

My 2.4 had a NV2550. It's very common, even at 61k, that there's a little bit of metallic material on the plug. Mine didn't whine anywhere near like that. It stops in neutral? Does it stop if you let off the throttle and take the load off?

Hopefully someone with the 6 speed can chime in. These transmissions are frequently swapped out for AX-15's in the 4.0's as they're notoriously weak. Strawberry milkshake coming out of your transfer case isn't really good either.
 
My 2.4 had a NV2550. It's very common, even at 61k, that there's a little bit of metallic material on the plug. Mine didn't whine anywhere near like that. It stops in neutral? Does it stop if you let off the throttle and take the load off?

Hopefully someone with the 6 speed can chime in. These transmissions are frequently swapped out for AX-15's in the 4.0's as they're notoriously weak. Strawberry milkshake coming out of your transfer case isn't really good either.

Sound stops out of gear and with clutch in, coasting in gear.
 
My 2.4 had a NV2550. It's very common, even at 61k, that there's a little bit of metallic material on the plug. Mine didn't whine anywhere near like that. It stops in neutral? Does it stop if you let off the throttle and take the load off?

Hopefully someone with the 6 speed can chime in. These transmissions are frequently swapped out for AX-15's in the 4.0's as they're notoriously weak. Strawberry milkshake coming out of your transfer case isn't really good either.

...the fluid looked fine from the tranny otherwise, so I would have suspected a transfer case bearing with the state of that fluid.
 
...the fluid looked fine from the tranny otherwise, so I would have suspected a transfer case bearing with the state of that fluid.

I could see a failing TC bearing quieting up when removing the load on it. I know pinion bearings can do that. The best advice I gave you is to post the sound via YouTube so someone with more experience can help. Beyond that, I'm not much of a gearbox guy and I don't wanna start spewing guesses. Best of luck; you can probably find replacement TC's on car-part.com fairly cheap if you end up having to R/R or if you choose not to rebuild.
 
For the TC, is the breather connected and in-tact?

It appears to be. It's hard to see it where it where it starts with the skid plate in place. I "felt" it on the Tx case housing and traced the tube over the tranny and I can see it (I believe) zip tied to the refrigerant hoses on the passenger side of the engine bay. I'll check again tomorrow.
 
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