Which Transfer Case fluid for 2004 Diesel 2500HD 4 wheel drive

[k_graham]

GM manual states Manual Transfer Case - Dexron 3 Automatic Transmission fluid.

Automatic Transfer Case - Auto-Trak 2 Fluid

 

This particular unit requires pushing a button to change between 2 and 4 wheel drive - my thought is that is still a Manual Transfer case but I would like confirmation.

 

Thanks.

Ken

Edited October 14, 2021 by k_graham
Clarity, readability

[CamGTP]

A manual transfer case would have a lever on the floor. Push button is an automatic transfer case.

So you need the Auto-Trak 2 fluid.

[Black02Silverado]

Yes, Auto-Trak 2 or you can use AMSOIL's ATL fluid.  That  is what I put in my 2002 Silverado's Auto transfer case.

[davester]

It's my understanding that the "manual" transfercase description is for both the stick shift AND the electric shift setup, and you should use a DexIII fluid in them (and DexIII is preferred over DexIV as some people have found the seals would leak when they used DexVI).

 

The "automatic" transfercase is for the 1500's that included the AWD setting (which the 2500s/3500s of that era never had).

[David89GMC]

If you have pushbuttons, you have an automatic transfer case. If you have a floor shifter, you have a manual transfer case. The two transfer cases are quite a bit different. 

There is an option with pushbutton transfer cases to shift into 4wd when in Auto mode according to the traction control option. 

The other poster is incorrect, he may not have the user's manual in front of him, because it shows the following diagram.

You are correct about the two fluids for the manual and automatic (electronic) transfer cases.

 

The tag on the back of the transfer case will indicate the model you have.

 

149 is mechanical

The others are electronic (automatic)

 

[jake111]

davester is correct.  ALL of the diesels in 2004 (and similar years at least) with 4wd have a MANUAL transfer case.  They came with 2 shifting styles (1) manual shift on the floor, and (2) push button shift (but NOT with an automatic or AWD button).  The push button electric shift simply does the same thing as the manual floor shift (you can look at the transfer case).

 

Dex-III is the proper fluid.  Since that is officially no longer available, you should be able to find something labeled "for GM 2005 or older" or Dex/Merc ATF.  GM "retired" Dex-III and at first claimed Dex-VI was fully compatible, but it isn't, and should NOT be used.  The manual transfer case is simple enough that just about any oil will do (some even use engine oil).  The expensive auto-trak fluid won't hurt it either, but isn't needed at all.

 

The bigger issue with these transfer cases is "pump rub".  The pump is suppose to rub against a hard steel clip in the magnesium tail shaft.  Eventually, the steel clip breaks or slip out of position and the pump wears a pinhole in the case.  The fluid leaks out over a period of months so it isn't noticed . . . until the transfer case runs dry . . . 

 

[added after-thought]  There are several "pump rub" kits available to avoid this problem.  There are also aluminum tailshafts available.

Edited October 14, 2021 by jake111

[davester]

2 hours ago, David89GMC said:

If you have pushbuttons, you have an automatic transfer case. If you have a floor shifter, you have a manual transfer case. The two transfer cases are quite a bit different. 

There is an option with pushbutton transfer cases to shift into 4wd when in Auto mode according to the traction control option. 

The other poster is incorrect, he may not have the user's manual in front of him, because it shows the following diagram.

You are correct about the two fluids for the manual and automatic (electronic) transfer cases.

 

The tag on the back of the transfer case will indicate the model you have.

 

149 is mechanical

The others are electronic (automatic)

 

 

This is only partially correct:

The NVG 149 and 246 transfer cases are AWD, and they need AutoTrak fluid.

The NVG 261 & 263 transfer cases are not, and they need (or rather, are spec'ed) DexIII.

 

The 261 and 263 transfer cases are almost identical internally and share most of their parts, the primary difference between them is manual shift vs electric shift (which is a motor moving the shift fork instead of a lever).

 

The 263 does not need Autotrak fluid, even though it has electric shift, is because it doesn't have the AWD clutch packs that the 149/246 TC's have.

 

The 2500/3500 GMT800 series trucks (which the o.p. has) never came with, and don't have an AWD option.  His TC takes DexIII.

 

Edited October 14, 2021 by davester

[Z45]

10 hours ago, CamGTP said:

A manual transfer case would have a lever on the floor. Push button is an automatic transfer case.

So you need the Auto-Trak 2 fluid.

The electric is similar but without the AUTO button.

 

Quote

This information applies to 2007 and prior GM passenger cars and trucks.

Dexron III is being phased out as a product name. It is being renamed Manual Transmission Fluid and carries p/n 88861800 U.S. (88861801 Canada).

If fluid p/n 88861800 U.S. (88861801 Canada) is not yet available when servicing a manual transmission or transfer case, Dexron III can be used in its place.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Unavailability of manual transmission fluid part number 88861800 U.S. (88861801 Canada).

Recommendation/Instructions:
If fluid part number 88861800 U.S. (88861801 Canada) is unavailable when servicing a manual transmission or transfer case, Dexron III can be used in it's place. DO NOT use Dexron VI in place of the manual transmission fluid in any manual transmissions or transfer cases as a failure may result.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

 

Edited October 14, 2021 by elcamino

[k_graham]

9 hours ago, jake111 said:

 

The bigger issue with these transfer cases is "pump rub".  The pump is suppose to rub against a hard steel clip in the magnesium tail shaft.  Eventually, the steel clip breaks or slip out of position and the pump wears a pinhole in the case.  The fluid leaks out over a period of months so it isn't noticed . . . until the transfer case runs dry . . . 

 

[added after-thought]  There are several "pump rub" kits available to avoid this problem.  There are also aluminum tailshafts available.

Thank you for this information Jake. May I ask your preference in a kit or aluminum tailshaft preference?

Is it a simple preventative maintenance or requires removal and disassembly of the entire unit?

[davester]

To install a pump rub fix, you need to take out/disassemble the transfer case.

 

Fixes range from:

-pressed metal plate that is placed on the existing oil pump

-replacement billet oil pump

-replacement tail housing made of a different metal

 

They all work and take basically the same amount of time and effort to install, I would just go with the cheapest option (the pressed metal plate).  It's what I used 6 years ago when I upgraded my truck to 4wd.

[jake111]

Yep, there are several options as davester listed above.  I went with what I think was the first solution, from Merchant Auto which is on the expensive side, but that's what it was 10-ish years ago.  Other cheaper pump plates with wide ears are available now.

 

Unfortunately, you have to take the transfer case out and apart to install any of these solutions.  And there are some tricks you have to learn to get it apart.  (My brother knew the tricks and already had a jig to hold the transfer case, so I don't know details.)

 

The red-neck solution is just to find the pinhole, clean it up, and JB Weld it.  Of course, you have to wait for the pinhole!!  Or guess where it will be.

Edited October 15, 2021 by jake111

[newdude]

On 10/13/2021 at 8:57 PM, k_graham said:

GM manual states Manual Transfer Case - Dexron 3 Automatic Transmission fluid.

Automatic Transfer Case - Auto-Trak 2 Fluid

 

This particular unit requires pushing a button to change between 2 and 4 wheel drive - my thought is that is still a Manual Transfer case but I would like confirmation.

 

Thanks.

Ken

 

On 10/13/2021 at 9:24 PM, CamGTP said:

A manual transfer case would have a lever on the floor. Push button is an automatic transfer case.

So you need the Auto-Trak 2 fluid.

 

 

No.  See further below.  Push button cases in the HDs are still a manual transfer case as they do not posses the AUTO function.

 

 

On 10/14/2021 at 1:19 AM, David89GMC said:

If you have pushbuttons, you have an automatic transfer case. If you have a floor shifter, you have a manual transfer case. The two transfer cases are quite a bit different. 

There is an option with pushbutton transfer cases to shift into 4wd when in Auto mode according to the traction control option. 

The other poster is incorrect, he may not have the user's manual in front of him, because it shows the following diagram.

 

You are correct about the two fluids for the manual and automatic (electronic) transfer cases.

 

The tag on the back of the transfer case will indicate the model you have.

 

149 is mechanical

The others are electronic (automatic)

 

 

 

 

 

2500HD is really easy.

 

- BOTH the floor shift AND the push button shift 2001-2010 are called MANUAL transfer cases.  The only difference between the two is how they are shifted.  They are NOT AUTO transfer cases because they do not possess the AUTO button/AUTO TRAK transfer case.

 

- AutoTrakII fluid is NOT the correct fluid for a 2500hd/3500hd transfer case.  The correct fluid 2001-2007 classic is GM Manual Transmission and Transfer Case fluid, GM # 88861800.  OR, if you can't find that at your dealer or local ACDelco store, you can use any Dexron III fluid.  

 

- Do NOT use Dexron 6 in these transfer cases.  Fluid is not compatible with the seals.  

Edited October 15, 2021 by newdude