Transfer case stupid question thread

Sunbelt56 said:

I recently just purchased this truck (94 K3500 4wd) and put it up on 4 jack stands so all 4 tires cleared the floor. With the #7 fuse out, I can put the floor shifter into 4H and just the back tires spin. So I put the fuse back in and shift it from 2H to 4H and I hear a gosh-awful grinding noise. So am I correct in assuming the transfer case is ok and the front differential has a broken chain or something?

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No chain in the front end. I can't think of anything that would grind if the truck is stationary and in neutral when you put it in 4hi. I've never known a bad actuator to make noise, but that's where I'd start.

Just unscrew it from the housing and check it's function while it's out. Should extend in 4x4. Perhaps it could be making the mystery noise.

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It makes a grinding noise when I put it in Drive and 4H. I haven't checked it with the key on and the engine off in Drive and 4H yet.

I still am having T-case problems, changed the push button switch in the dash, shift motor on T-case, and the front differential locking switch or what ever it is, and now I need to know if my early 99 Chevy Tahoe has a transfer case control module in the dash behind the head light switch like the book shows, it's in the middle of the body change year and I'm finding out some of the stuff is the older style and some is the newer style, begining to hate this vehicle.

Ok I have a stupid question.

What is the approved fluid I can run in my shift on the floor NP241c

I keep hearing you're not supposed to use dextron vi in an older tcase and should run dexron III from companies that still make it for older vehicles.

I have some Maxlife ATF... Can I use that without issues?

luconi said:

Ok I have a stupid question.

What is the approved fluid I can run in my shift on the floor NP241c

I keep hearing you're not supposed to use dextron vi in an older tcase and should run dexron III from companies that still make it for older vehicles.

I have some Maxlife ATF... Can I use that without issues?

Click to expand...

I'm curious where you read/heard not to use Dex 6 in older transfer cases... I've been running Dex 6 in the NP243 in my '97 Suburban for the past few years with no issues. As far as I'm aware that's the current fluid recommended by GM.

GM specifically said not to in a bulletin. That's why they kept "Manual transmission and transfer case fluid" which was Dexron III under a different name. Technically they couldn't call it Dexron III because they stopped certifying that spec but its the same.

Edit: the bulletin is #04-07-30-037D. The notes about manual transfer cases are towards the bottom of the first page:
"The content of this bulletin does not apply to manual transmissions or transfer cases. Any
vehicle that previously required DEXRON®-III for a manual transmission or transfer case
should now use P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case
Fluid. Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid."

MIHELA said:

GM specifically said not to in a bulletin. That's why they kept "Manual transmission and transfer case fluid" which was Dexron III under a different name. Technically they couldn't call it Dexron III because they stopped certifying that spec but its the same.

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I saw that bulletin posted somewhere on the internet (yeah, I know--the internet). It said do not use synthetic ATF in the older T-cases. IIRC, it mentioned the NP241 and NP243 specifically. At the time I had synthetic in one of my T-cases, so I drained it and put good 'ol DEX III back in......

And I do keep the fluid in my transfer cases bright red, too......

alpinecrick said:

I saw that bulletin posted somewhere on the internet (yeah, I know--the internet). It said do not use synthetic ATF in the older T-cases. IIRC, it mentioned the NP241 and NP243 specifically. At the time I had synthetic in one of my T-cases, so I drained it and put good 'ol DEX III back in......

And I do keep the fluid in my transfer cases bright red, too......

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Here's a link to the PDF of the TSB.

https://www.bimmerfest.com/forums/attachment.php?attachmentid=307128&d=1325712075

No specific mention of the NP241 or NP243, although they do fall under the specified year range. I'm not doubting the TSB but I find it odd that there's no mention of why this is the case. I see people in various threads saying seal incompatibilities, but I can't find any hard info from GM.

luconi said:

Ok I have a stupid question.

What is the approved fluid I can run in my shift on the floor NP241c

I keep hearing you're not supposed to use dextron vi in an older tcase and should run dexron III from companies that still make it for older vehicles.

I have some Maxlife ATF... Can I use that without issues?

Click to expand...

To answer your question, it looks like the correct GM recommended fluid for an NP241 would be GM 88861800 Manual Transmission and Transfer Case Fluid.

https://www.amazon.com/Genuine-Fluid-88861800-Manual-Transmission/dp/B00BK7M1EK

Looks like I'll be buying some for my NP243 as well.

df,
That bulletin is different than the one I saw, although the one I saw posted might be older and has been superseded by the one you posted.