Transfer Case Fluid Change Tips

[rbattelle]

This evening I changed the transfer case fluid on my truck for the first time and thought I'd post my advice (take it or leave it) in case someone else out there might benefit from it.



You will need the following items to do the job:

-A 10mm hex driver socket or 10mm allen wrench.

-A large-diameter drain pan... one of those Wedco 5-gallon pans will work.

-Some rags.

-3 quarts of ATF+4 (or your favorite t-case fluid).

-A suction gun.



There are only 2 plugs on the back of the transfer case: the lower one is for draining and the upper is for filling. Torque spec on them is 30-40 lb-ft. Fluid capacity is listed in the service manual as 4 pints (2 quarts).



1. Clean the area around the drain and fill plugs. Remove the drain plug. If you have the skid plate under the transfer case the fluid will exit the drain, flow onto the skid plate, and pour over the edges of the plate in 6-10 different places in a roughly 1-ft circle (hence the need for a large diameter drain pan). This is if you're on level ground. You can certainly catch it all, just be prepared for it!



2. Remove the fill plug and re-install the drain plug after all the old fluid has drained.



3. Using the suction gun, suck fluid out of one of the ATF+4 containers, then insert the gun tube into the fill hole and squeeze out the fluid. My suction gun takes in about 1 pint per suck. During this procedure it's important to bear in mind that the transfer case has no filtration and hence no ability to remove contaminants from the fluid (there is a magnet, but you have to crack open the case to get to it). That means you've got to be careful to keep the suction gun hose from contacting dirty underbody components on its way into the fill hole.



4. Re-install the fill plug.



I used no thread sealant on either plug. Although the factory spec is 2 quarts, mine took just about 3 full quarts to fill to the bottom of the fill hole, so you should buy at least 3 quarts of whatever fluid you intend to use.



My mileage is 39100 and the fluid that came out looked, smelled, and felt like good clean ATF. Factory recommended change interval is 45000 miles, and it appears that's quite reasonable.



Attached is a pic showing the plug locations. This procedure was done on a manual shift unit (NV271), but the procedure is identical for the NV273 (electric shift).



-Ryan

 

[Briman]

Nice job Ryan. I always take out the fill plug first. My point being: if you can't get the fill plug out, don't take out the drain plug. A pump works as well as a suction gun too.

 

[klenger]

I'll try to add your comments to my website.



Thanks

 

[rbattelle]

I'll try to add your comments to my website.

I figured you'd jump on the torque specs for your database.



Briman - excellent point. So simple it never occurred to me. Ironic that you point that out, because when I was under there and I removed the drain first it dawned on me that if I broke the fill plug getting it out I'd be in trouble. For some reason the fill plug was torqued much tighter than the drain from the factory. Oh, and one of those fluid transfer pumps also works nicely (maybe even more convenient than the suction gun)... I should invest in one.



-Ryan

 

[mberry]

Thanks Ryan! I am going to do this as soon as weather permits.

 

[04 Diesel Power]

Thanks, I am getting ready to change mine. I have 24,000 miles on mine.

 

[mfrost]

It would seem that DC would positions that skid plate so that nice big hole it could be used to drain the oil instead of totally giving it a bath in ATF.



Put two guarts in as the book said then read the book again after driving it for 2 days. Had bad thoughts about it not being to the bottom of the fill hole, so under I went again and sure enough I added a half quart more. Just happened to have half a quart since I overfilled the transmission by that much. That newly installed drain plug sure came in handy.

 

[miller_wb]

Nice write up. FWIW, my truck has a skid plate. I removed the skid plate first. I also needed to clean off pipe seal that was on both plugs. Just an interesting observation, my 2003 owners manual under schedule B shows a transfer case fluid change at 45K, 60K, and 120K.

 

[BNH4221]

Perhaps I might add a little trick to reduce the skid plate mess?



I took a used Rotella T jug (gallon size) and cut away the front (face) side of it. Just the face, not the sides or bottom. I left the bottom on but shaved the edge down. This made the jug into a sort of mini drain pan.



I slid the jug between the T case and the skid plate so that the bottom edge just fit under the T case. This left the spout extended over the edge of the skid plate and poised nicely over the drain pan.



It saved me much mess. Oh, I still spilled, but not as much. And it beat the heck out of taking the skid plate off.



One caveat. This was on my '98. Haven't looked under the '04 yet, but I assume it is pretty much the same.



Best,

Steve

 

[MLimpert]

Just a helpful hint to avoid a mess:



The last time I did one I used a gallon jug with a funnel in the top of it. I removed the skid plate and pulled the plug. I accidentally dropped the plug into the funnel, and I found out quickly the plug is just the right size to cover the opening in the bottom of the funnel! Needless to say I had a large mess...

 

[rbattelle]

I accidentally dropped the plug into the funnel, and I found out quickly the plug is just the right size to cover the opening in the bottom of the funnel! Needless to say I had a large mess...

Sorry, Matt, but that's really funny. Reminds me of the kind of bafoonery I'm usually subjected to! :-laf



-Ryan

 

[MLimpert]

Yeah, I was pretty hot when it happened! Thank goodness for kitty litter. The thing that bothers me the most is that was probably the 3rd time I'd used that method with no previous problems.

 

[ThomasLawrence]

How about the dummy (that would be me, by the way) that stands behind (DIRECTLY behind) the transfer case - drain positioned under the T-case, and removes the drain plug... neglecting the laws of gravity and the properties of fluid under pressure (said pressure created by said gravity acting on said fluid) - all of which combine to propel the fluid in a well-defined parabolic arc, who's path happens to intersect with the aforementioned dummy's chin.



ATF+4 not only smells bad - it also tastes bad. Not quite the pungency of 90W gear oil, but it's in the ballpark.



-Tom

 

[Bill Stockard]

How about the dummy (that would be me, by the way) that stands behind (DIRECTLY behind) the transfer case - drain positioned under the T-case, and removes the drain plug... neglecting the laws of gravity and the properties of fluid under pressure (said pressure created by said gravity acting on said fluid) - all of which combine to propel the fluid in a well-defined parabolic arc, who's path happens to intersect with the aforementioned dummy's chin.



ATF+4 not only smells bad - it also tastes bad. Not quite the pungency of 90W gear oil, but it's in the ballpark.



-Tom

:-laf :-laf :-laf

What are us 4x2 owners missing!!



Bill

 

[klenger]

I have posted Ryan's instructions on my website at http://www.klenger.net/dodge/general-reference/xfer-case-fluid-change/index.html

 

[rbattelle]

I have posted Ryan's instructions on my website at http://www.klenger.net/dodge/general-reference/xfer-case-fluid-change/index.html

WOW! I'm famous! Oo. Thanks for crediting me with that, Klenger!



My name in print. Things are going to start happening to me now! Woo Hoo!



-Ryan

 

[Tony T.]

Thanks Ryan for the info, now I wonder if the wife will miss her turkey baster. :-laf that will make a good suction pump.



Tony

 

[rbattelle]

Thanks Ryan for the info, now I wonder if the wife will miss her turkey baster. :-laf that will make a good suction pump.



Tony

And an interesting Thanksgiving in 2005!!

 

[Anders]

NV271 drain/fill plug torque discrepancy

The 2006 factory service manual (part# 81-370-06059) has a discrepancy on the torque settings for the drain/fill plugs on the NV271 transfer case. On page 1649 "STANDARD PROCEDURE - FLUID DRAIN AND REFILL" it says the torque setting is 30-40 ft. lbs. On page 1645 "SPECIFICATIONS - TRANSFER CASE - NV271" it says the torque setting is 15-25 ft. lbs. That's quite a difference.



Since I was doing a fluid change I read the "STANDARD PROCEDURE - FLUID DRAIN AND REFILL" first. I set my torque wrench to 35 ft. lbs. , in the middle of the 30-40 range, and started tightening the drain plug. After a good number of turns, it seemed like the plug was going in way too far and not getting any tighter and I had not reached 35 ft. lbs. yet. I got nervous and started crawling through the manual. I found the "SPECIFICATIONS - TRANSFER CASE - NV271" page, where it said the torque setting was 15-25 ft. lbs. Well, it turns out I had reached 25 ft. lbs. on the drain plug, so I left the cheap little steel drain plug where it was, buried a good 1/8" inch deep in that expensive aluminum casting.



When it was time to tighten the fill plug, I set the torque wrench to 20 ft. lbs. , the middle of the 15-25 range, and I reached the torque setting much sooner. Not all the threads of the fill plug were engaged. I went up to 25 ft. lbs. , and the fill plug set itself in the transfer case nice and flush.



In conclusion, when torquing the drain/fill plugs on the NV271 transfer case, I would advise going with the the 15-25 ft. lbs. as specified on the "SPECIFICATIONS - TRANSFER CASE - NV271" page of the factory service manual and not the 30-40 ft. lbs. as specified on the "STANDARD PROCEDURE - FLUID DRAIN AND REFILL" page.

 

[rbattelle]

Anders - wise advice. Thank you for pointing out the discrepancy.

On plugs like this, I use the 'ol mental torque wrench, but there's certainly something to be said for doing it by the factory specification.

Ryan