• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

NP242 case fluid change?????

Ecomike

Ecomike

NAXJA# 2091
NAXJA Member
Location
MilkyWay Galaxy
I am trying to finish swapping my aw4, out, and am having a tough time finding the drain and fill plug locations on my NP242 transfer case, 87 XJ.

There is a bottom plug, and two side plugs, a 1/4" rubber plug up high on the other side and a vent line up top. I pulled the speedometer gear, and it looks like a good fill spot, but it looks like a separate chamber, and looks and smells like it had oil it before, not Tranny fluid. Is it a separate fluid? where is the fill line / limit? the fill location options, and so on???

It is holding up reinstalling the Aw4 and T-case, so I am in a hurry. It looks empty now, but not sure?
 
The drain plug should be on the rear of the case and be about a 1 1/4" hex bolt. The fill plug is identical just above it a bit. Both plugs are right near the round ID tag. ATF is all it needs.
 
yep. the two big hex head bolts on the back under the ID tag. lower one is drain, upper is fill. fill it up until fluid comes out of the fill hole.

that rubber plug on the top near the front is an access hole to remove the roll pin to get the shift selector rail out.

the bottom bolt is not for draining, it is the shift detent ball and spring mechanism.
 
--Picture it mounted up in XJ--
as above post - back side by tag
on a 96-242 - the bottom plug is drain. About (?) 3inches above identical plug is fill.
(older 242 had ? allen sockets ? maybe)
-2.85 Pints Dex lll
fill to lower edge of fill opening.
BE SURE TO GET FILL PLUG OUT FIRST.
 
cruiser54 said:
The drain plug should be on the rear of the case and be about a 1 1/4" hex bolt. The fill plug is identical just above it a bit. Both plugs are right near the round ID tag. ATF is all it needs.
Click to expand...

I found a nice image:

http://www.jeepkj.com/forum/showthread.php?t=30383

The $%#@&^%$ is almost 1-1/4, but not 1-1/4 and not 1-1/8, and all my large sockets are US, not metric, POS nuts! LOL, I used an adjustable, fits all wrench!

Turns out this 24 YO, NP242 has never had anything but motor oil in it. Looked like it had never been changed either!!! It was black, like well used diesel oil, and about the viscosity of gear oil that smelled like a sulfur plant. I put API SL grade 20W50 back in it.

We got it all together, and bolted back on the engine today!!!
 
I would change out the oil for ATF,not sure how the pump would like the 20/50.
 
RCP Phx said:
I would change out the oil for ATF,not sure how the pump would like the 20/50.
Click to expand...
I am afraid ATF would leak and have compatability issues. 20W50 in Houston climate should not be a problem, the remains I drained out was at least that thick, and it never leaked.

Cruser54, not sure what gear oil sounds like (LOL) but it sure smelled like gear oil, LOL!
 
1990JEEPXJ said:
why would ATF leak and not be compatible if that is what it came with from the factory?
Click to expand...

Not sure what this 87 had in it in 87, but it was obvious to me it had oil in it since hell froze over when I opened the drain. It is never good to completely change out fluids using completely different fluids on a drain and fill on old beast like this. Better to stay with what was in there, especially if it has had no prior problems. I bought the rig used in 2004, and this was the first time I drained it. It has 278,xxx miles on it.

Trans fluid is much more likely to leak through old seals than oil.
 
Ecomike said:
Not sure what this 87 had in it in 87, but it was obvious to me it had oil in it since hell froze over when I opened the drain.
Click to expand...

True, but that doesn't mean that a PO didn't replace factory ATF with gear oil at some point. Probably a good 25 to 30% of the junkyard cases I've looked at have had someone make that mistake in the past.

It is never good to completely change out fluids using completely different fluids on a drain and fill on old beast like this. Better to stay with what was in there, especially if it has had no prior problems. I bought the rig used in 2004, and this was the first time I drained it. It has 278,xxx miles on it.

Trans fluid is much more likely to leak through old seals than oil.
Click to expand...

Point taken, but gear oil likely isn't the best thing for the pump to be trying to slosh around either. If it's gone this long on gear oil, replacing it with ATF may not be necessary - but it's a crapshoot. I'd be inclined to change out for ATF simply because that's what it's known to need, inspect for leaks at 100 miles, then change that out for fresh ATF and re-inspect at another 100 miles, but I get where you're coming from. Your call on that one.
 
casm said:
Point taken, but gear oil likely isn't the best thing for the pump to be trying to slosh around either.
Click to expand...

Why not? I have read many posts here where oil was mentioned as an acceptable option for Transfer cases, even by 5-90 IIRC.
 
Ecomike said:
Why not? I have read many posts here where oil was mentioned as an acceptable option for Transfer cases, even by 5-90 IIRC.
Click to expand...

My concerns with it would be the following:

- Mineral oil (gear oil) vs. synthetic (ATF).

- Viscosity and lubricity (see above).

- Long-term reliability, including seals.

Note that I'm not saying it can't be done, or even that it's necessarily harmful in this specific instance - just that I'm not sure that there's a benefit to using something other than what it was intended to have.
 
I don't see any issues with removing the 20/50 and replacing with ATF. Fact is you have no idea what was even in there - you are assuming that it has had motor oil for its whole life (which in fact it hasn't since they came from the factory with ATF) So the 20/50 might be changing from one type of oil to another. Drain, put in some cheap cheap cheap ATF and drive for a few hundred miles to flush it, then drain and refill with something decent. I've got Mobil 1 Synthetic ATF in mine.
 
Last edited:
DieselSJ said:
I don't see any issues with removing the 20/50 and replacing with ATF. Fact is you have no idea what was even in there, so the 20/50 might be changing from one type of oil to another. Drain, put in some cheap cheap cheap ATF and drive for a few hundred miles to flush it, then drain and refill with something decent. I've got Mobil 1 Synthetic ATF in mine.
Click to expand...


This is what I would do. Those t/cases are intended to have a lubricant with the viscosity and film strength of ATF.
 
DieselSJ said:
I don't see any issues with removing the 20/50 and replacing with ATF. Fact is you have no idea what was even in there - you are assuming that it has had motor oil for its whole life (which in fact it hasn't since they came from the factory with ATF) So the 20/50 might be changing from one type of oil to another. Drain, put in some cheap cheap cheap ATF and drive for a few hundred miles to flush it, then drain and refill with something decent. I've got Mobil 1 Synthetic ATF in mine.
Click to expand...

I have Autozone 20W50, API SL grade in mine now. It had a medium viscosity oil in it since 2004, for at least the last 55,000 miles with absolutely no problems. I will be sticking with the 20W50. I have more faith in the oil than ATF.

And Dex II, III was what the OEM fill was claimed to be, not synthetic, Mobil 1, ATF-4 or any other new fangled ATFs. :rolleyes:
 
You must log in or register to reply here.

Similar threads

D
Temp Gauge Reads High With New Senosr
Replies
15
Views
1K
TheDXJ
T
F
Source of Gearbox leak?
Replies
3
Views
1K
cruiser54
C
W
AW4 no forward or reverse
Replies
2
Views
1K
wireman121
W
O
0331 Strikes Again...?
Replies
11
Views
301
Ol Blue
O
O
Brake failure light randomly coming on
Replies
4
Views
2K
RCP Phx
R
Back
Top