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242 cooler??

nochance9

nochance9

NAXJA Forum User
Location
ogden ut
Hey, my 242 is shot and i just picked one up from the junk yard along with a stock tranny cooler. I was hoping that there might be a way for me to make it into a transfer case cooler. Has anyone done this before? Or is it even possible? i was thinking of just taping it inline with the line that goes from the transfercase to the transmission, but i don't know how much fluid gets pumped through there or if it's at a high enough pressure to pump fluid through a cooler.

Any input is very welcome thanks.
 
The 242-AMG used in the military HMMV and the H1 Hummer has a cooler, but it just shares fluid with the transmission. I don't know how the pump works internally, if there even is one (it may use the tranny cooler pump for pressure and vacuum). You might want to read up on that for some ideas.
 
there's no need. The pump in the 242 simply pumps fluid for lubrication, it's a mechanical transfer case, so it doesn't generate heat like an automatic transmission that relies on the fluid to do work.

The most useful mod that you might do is add two fittings top and bottom with some clear hose in between, a sight glass for your T-case fluid level.
 
The only line coming from the transfer case is the vent.
 
I doubt you are going to have much luck with it. The itty-bitty little pump in the 242/231, how would you even plumb into the case, and if you did add it somehow to the transmission cooler line the temperature might in fact be increased.

Not saying it can't be accomplished, and it would make one hell of a write up if you did it.

You might be able to drill out and install a fitting on the drain plug and rig up something for a little extra fluid capacity.
 
87manche said:
there's no need. The pump in the 242 simply pumps fluid for lubrication, it's a mechanical transfer case, so it doesn't generate heat like an automatic transmission that relies on the fluid to do work.

The most useful mod that you might do is add two fittings top and bottom with some clear hose in between, a sight glass for your T-case fluid level.
Click to expand...

That's a good idea for the fluid level thing, i always hate pulling that big plug to check it, and it might be an easier way to fill it up too. Which is also a pain to do.

ehall said:
The 242-AMG used in the military HMMV and the H1 Hummer has a cooler, but it just shares fluid with the transmission. I don't know how the pump works internally, if there even is one (it may use the tranny cooler pump for pressure and vacuum). You might want to read up on that for some ideas.
Click to expand...

Yeah, i know the hummer ones have them only cause i really wanted one for a replacement, only problem is getting your hands on one.

But there is an internal pump in the 242, i just don't know if i could possibly use it for this.

RCP Phx said:
The only line coming from the transfer case is the vent.
Click to expand...

And it vents into the transmission??

joe_peters said:
I doubt you are going to have much luck with it. The itty-bitty little pump in the 242/231, how would you even plumb into the case, and if you did add it somehow to the transmission cooler line the temperature might in fact be increased.

Not saying it can't be accomplished, and it would make one hell of a write up if you did it.

You might be able to drill out and install a fitting on the drain plug and rig up something for a little extra fluid capacity.
Click to expand...

I was always planning on running two coolers, but one of them i was thinking might be able to go in the line that runns between the tcase and the tranny. You're probably right about the tranny fluid making the transfercase fluid hotter, so if i did get this to work somehow i would want to keep the two completely separate... Which complicates things quite a bit i would think. I'm going to tear into it this week and i'll scope it out on the inside, see if there's any way to tap into it somewhere. I guess i could use an external pump that just pulls it from the bottom of the case and pumps it into the top with a cooler in line somewhere, but that could get expensive...

Thanks for all the input! Keep it coming. :D
 
I'm sure you could do it, but it'll take a significant amount of work (since you're working on putting a Supra motor into an XJ, I don't think that'll dissuade you :spin1:) and I'm not sure it will help much. The only things I would worry about are (a) is the pump strong enough to handle the extra resistance? and (b) the extra fluid volume required. You'd have to keep the cooler at or below the level of the fill plug or you will have to find a way to "overfill" the case above the fill plug to have the case not run low on fluid.
 
I'd be tempted to just install a couple of barb fittings and then extend the tranny cooler return through the 242--let the tranny pump push and pull the fluids. OTOH there is no real benefit to the 242 from cooling the fluid, and there is measurable risk from starving the AW4, so I wouldn't do it unless I could prove that it would always work right. I'd also add an inline filter to the line between the 242 and AW4 if I could
 
Begster said:
Nope, it vents into the atmosphere, just like your axles do.
Click to expand...

Then what is the line going from the top of the t case to the tranny?

kastein said:
I'm sure you could do it, but it'll take a significant amount of work (since you're working on putting a Supra motor into an XJ, I don't think that'll dissuade you :spin1:.
Click to expand...

I'm not the one working on the Supra engine swap... But if anyone wants to install one for me i'm down! haha 2jz in an xj would be BA!


ehall said:
I'd be tempted to just install a couple of barb fittings and then extend the tranny cooler return through the 242--let the tranny pump push and pull the fluids. OTOH there is no real benefit to the 242 from cooling the fluid, and there is measurable risk from starving the AW4, so I wouldn't do it unless I could prove that it would always work right. I'd also add an inline filter to the line between the 242 and AW4 if I could
Click to expand...

Yeah, i really wouldn't want to combine or integrate the the tranny and tcase fluids. For the heat or because i wouldn't want to risk running either of them dry. This is looking less and less possible the more i think about it. I looked for external oil pumps but unless i want to run one off my fan belt i'm SOL.
 
The pump in the NP242 is simply a small gearotor job, meant to "lift" the fluid to the top of the case. The internals are splash lubricated from the pump discharge (no pressure.)

If you want to cool the thing, you'll probably have to add a pump to circulate it through the cooler - I'm sure the small gearotor job won't do it for you. You don't need pressure so much as volume - the pump will just need to move fluid about (say, 1-3gpm or so @ 5psig?) You can go with a bit higher volume flow, but I'd put in a rheostat to allow it to be reduced (I'd probably put in the rheostate anyhow, and monitor the temperature. The rheostat would allow for the fluid flow to be increased or decreased PRN.)

How to get into the fluid? I'd probably get a spare set of transfer case plugs to drill and tap, or measure them to have bushings made to accept a 1/4" NPT to -4AN or -4SAE adapter. Pull from the bottom, discharge at the top, just like you'd expect. Then, make sure the lines are kept well up out of the way. Have them follow the trasnmission cooler lines going forward, for simplicity.
 
nochance9 said:
Then what is the line going from the top of the t case to the tranny?
Click to expand...
That's probably the vent line, it doesn't connect to anything, just keeps the transfer case from being pressurized or pulling a vacuum due to temp/air pressure changes.



nochance9 said:
I'm not the one working on the Supra engine swap... But if anyone wants to install one for me i'm down! haha 2jz in an xj would be BA!
Click to expand...
oh, my bad, that's child9. Sorry, got the usernames confused :dunce:
 
For what its worth, the cooler in the M998/A1 thru M1114 HMMV is pretty much a 3/8 line that runs around the inside of the transfer case and is covered in fins about 1 inch square. The fluid in the line comes from the transmission and goes thru a combination engine oil cooler/transmission cooler mounted on top/in front of the radiator. We've long speculated if it was to help cool the transmission or heat up the transfer case fluid. Interestingly, the Uparmor M1152/M1165 series has a rear differential cooler that power steering fluid moves thru. Wrap your mind around that one.:wierd:
 
Can't find a pic real quick, but sprint cup cars use an external oil pump, driven off the drive shaft, to pump gear oil through a cooler. Maybe something like that mounted on the back of the transfer case would get you going.

edit; Still can't find the one I'm thinking of(belt driven pump), but a a Yahoo search for Differential Cooler Kits turned up these electric pump kits: (2nd - 6th results)
http://search.yahoo.com/search;_ylt...=Differential+Cooler+Kits&fr2=sb-top&fr=moz35
 
Last edited:
kastein said:
That's probably the vent line, it doesn't connect to anything, just keeps the transfer case from being pressurized or pulling a vacuum due to temp/air pressure changes.
Click to expand...
yep, you'll find that line is t'd into the vent line that travels up the bellhousing and to the firewall.
 
Sorry guy's, the best option i see is using a stand alone electric pump to suck fluid from the bottom and spray it in the top. But i can't seem to find an external electric oil pump that would do what i need. Also, with luck i'll be in moab in less than a week so the time crunch is on to get my tcase rebuilt. I think i'll have to put this idea on the back burner for a while. But maybe i sparked an idea in one of you more capable guys out there, I'll keep an eye out in the mod tech. :)
 
I wonder if DEX VI would stand up better to any heat in the transfer case?
 
Dex/Merc III. Dex VI is supposed to be backward compatible, but I don't have a definite answer.
 
nochance9 said:
My manual says to use merc. it's okay to use Dex VI?
Click to expand...

No reason why not:

1) Dexron specs are supposed to be reverse compatible. They seem to be, from experience. Haven't gotten any negative reports from the field on using Dexron VI in the AW4.
2) There aren't any clutches in the transfer case, unless it's AWD. The NP242 is merely differentiated 4WD, which is what gives you the "full time" option. Ergo, no trouble with friction modifiers - the ATF is used because it is thin and easy to distribute (little power required for the pump, a small gerotor is sufficient.)
3) It's there primarily for lubrication and cooling - you could use any 10-vis lubricating oil for it (some hydraulic fluids would work neatly as well, Type F ATF, Dexron II/IIE/III/VI, +3/+4, MerconV, and overseas OEMs...) The problem you hear about is when people dump +3/+4 into the AW4 and the clutches start to slip and chatter - because the +3/+4 fluid is Chrysler-spec, and the AW4 isn't a Chrysler box!)
 
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