Transfer case swapped and leaking... - North American Grand Cherokee Association

TheSharkster · 02-07-2010, 02:21 PM

Hey guys.... I did a TC swap from an NP249 to an NP231 in my 1995 GC Laredo with the 5.2. Before I installed it, I put new seals in. I took it for a drive, and it worked like a charm. I backed up my drive which has about a 5 degree angle, and parked it. I looked under to find fluid dripping out the front of the TC. I then turned the jeep around, thinking it would at least slow the leak until I take the tc out, and it was actually pumping fluid out more facing uphill. I mean it was pumping out the fluid.

Any ideas out there? I don't think the 231 is supposed to build up pressure inside, right? Just gears and a drive chain inside, right?

I love how the 231 works. I was so surprised how much more power my jeep seems to have now. Especially just pushing 2 wheels and not 4. And the fact I still have 4X4.

Sorry so long winded. I didn't want to leave anything out.

Thanks guys.....

JayH · 02-08-2010, 02:20 PM

Right, no pressure inside the case. The seal that's leaking is in the tail cone of the transmission and the tcase input shaft slides into and through it. You did match the tcase input shaft lengths from case to case, right???

TheSharkster · 02-08-2010, 03:05 PM

Quote:

Originally Posted by JayH

Right, no pressure inside the case. The seal that's leaking is in the tail cone of the transmission and the tcase input shaft slides into and through it. You did match the tcase input shaft lengths from case to case, right???

No I didn't. Very mechanically inclined, but a newbie in this area. Can I swap the input shaft from the 249 to the 231? It would be great if they would interchange. Wish I had done my homework on the different sized input shafts. Wouldn't have had to be laying on the cold ground reinstalling the 249 again today. I did do my homework on how to remove the input shaft so if the shafts can be swapped, I am prepared.

Adventure Bob · 02-08-2010, 04:04 PM

The fact that it bolted up and drives tells us that the length is right. The indication of wrong length would be a gap between the case and tranny (long t case input on a long tranny output) or it wouldnt drive under its own power (short tranny and short t case).
Leaking tells us that you either dinged the tranny seal or its pretty worn. Dorp the case and replace the tranny seal.

GreenMachine · 02-08-2010, 04:15 PM

Sounds like jay's on the money to me. you could have damaged or opened up that seal a bit upon removal/installation too. if it has leaked a bunch, you should see it on your tranny dipstick, or notice some slipping pretty soon. the seal was kinda tricky for me to replace, be patient with it...
my t-case also leaked a bit around the speedo plug after i re-installed it, but i think i just had it a tad over full because it has stopped leaking now, and the fluid is right at the top of the filler plug.
good luck

TheSharkster · 02-08-2010, 06:25 PM

Sounds logical to me also... but... why doesn't the tranny seal leak with the 249 installed? That's what gets me... I put the 231 in yesterday and it leaked like hell... put the 249 back in and it didnt leak... what do you think guys? Could the seal be that bad as to not leak on the 249? That's what gets me...

Could the input shafts be at different thickness? I do not have a micrometer to check this...

You guys are great... keep the info flowin...

JayH · 02-08-2010, 10:23 PM

The case input shafts are the same diameter and same number of splines. The 231 shaft is probably a half inch (or thereabouts) shorter. Not so short that you don't get spline engagement but short enough so that there are splines in the seal rather than seal surface in the seal.

TheSharkster · 02-09-2010, 01:37 AM

So the 231 input shaft is just a tad short, I understand. Do you think that I can use the 249 input shaft to replace the one in the 231?
I had just read a writeup on this subject on another sight(posted 2008) where a guy used an input shaft out of a 242 for his 231. I am hoping that I can use the one I already have.

JayH · 02-09-2010, 05:54 AM

You may be able to do that. The only way to know for sure is to crack open the cases and try.

Hmmm, actually my above scenario doesn't make sense as the tcase input shaft is female splines... it may still apply that its too short but it would just mean that the input shaft isn't fully engaged in the seal.

Pull the two cases and measue the length of the shaft protruing from the cases and go from there. Atbthe least, replace that seal (again).

ZJMAN · 02-09-2010, 09:12 AM

Quote:

Originally Posted by JayH

You may be able to do that. The only way to know for sure is to crack open the cases and try.

Hmmm, actually my above scenario doesn't make sense as the tcase input shaft is female splines... it may still apply that its too short but it would just mean that the input shaft isn't fully engaged in the seal.

Pull the two cases and measue the length of the shaft protruing from the cases and go from there. Atbthe least, replace that seal (again).

I think you've hit the nail on the head. The shaft is engaged but not enough to seal. Also could be rust/burrs/grooves on the OD of the t-case input shaft not allowing the seal to work.

02-07-2010, 02:21 PM	#1
TheSharkster Junior Member Grand Rookie Join Date: Sep 2009 Location: Pennsylvania Posts: 17	Transfer case swapped and leaking... Hey guys.... I did a TC swap from an NP249 to an NP231 in my 1995 GC Laredo with the 5.2. Before I installed it, I put new seals in. I took it for a drive, and it worked like a charm. I backed up my drive which has about a 5 degree angle, and parked it. I looked under to find fluid dripping out the front of the TC. I then turned the jeep around, thinking it would at least slow the leak until I take the tc out, and it was actually pumping fluid out more facing uphill. I mean it was pumping out the fluid. Any ideas out there? I don't think the 231 is supposed to build up pressure inside, right? Just gears and a drive chain inside, right? I love how the 231 works. I was so surprised how much more power my jeep seems to have now. Especially just pushing 2 wheels and not 4. And the fact I still have 4X4. Sorry so long winded. I didn't want to leave anything out. Thanks guys.....

02-08-2010, 02:20 PM	#2
JayH Super Moderator Grand Master Join Date: Jan 2002 Location: Maple Valley, WA Posts: 2,488	Right, no pressure inside the case. The seal that's leaking is in the tail cone of the transmission and the tcase input shaft slides into and through it. You did match the tcase input shaft lengths from case to case, right??? __________________ '95 Orvis - mostly... "If 10,000 people say a foolish thing, it is still a foolish thing."

02-08-2010, 04:15 PM	#5
GreenMachine Senior Member Grand Master Join Date: Feb 2007 Location: Central Washington Posts: 1,240	Sounds like jay's on the money to me. you could have damaged or opened up that seal a bit upon removal/installation too. if it has leaked a bunch, you should see it on your tranny dipstick, or notice some slipping pretty soon. the seal was kinda tricky for me to replace, be patient with it... my t-case also leaked a bit around the speedo plug after i re-installed it, but i think i just had it a tad over full because it has stopped leaking now, and the fluid is right at the top of the filler plug. good luck __________________ 95 4.0, family trail rig 01 4.7, pavement pounder

02-08-2010, 10:23 PM	#7
JayH Super Moderator Grand Master Join Date: Jan 2002 Location: Maple Valley, WA Posts: 2,488	The case input shafts are the same diameter and same number of splines. The 231 shaft is probably a half inch (or thereabouts) shorter. Not so short that you don't get spline engagement but short enough so that there are splines in the seal rather than seal surface in the seal. __________________ '95 Orvis - mostly... "If 10,000 people say a foolish thing, it is still a foolish thing."

02-09-2010, 05:54 AM	#9
JayH Super Moderator Grand Master Join Date: Jan 2002 Location: Maple Valley, WA Posts: 2,488	You may be able to do that. The only way to know for sure is to crack open the cases and try. Hmmm, actually my above scenario doesn't make sense as the tcase input shaft is female splines... it may still apply that its too short but it would just mean that the input shaft isn't fully engaged in the seal. Pull the two cases and measue the length of the shaft protruing from the cases and go from there. Atbthe least, replace that seal (again). __________________ '95 Orvis - mostly... "If 10,000 people say a foolish thing, it is still a foolish thing."

02-08-2010, 04:04 PM	#4
Adventure Bob Senior Member Grand Junkie Join Date: Feb 2009 Posts: 351	The fact that it bolted up and drives tells us that the length is right. The indication of wrong length would be a gap between the case and tranny (long t case input on a long tranny output) or it wouldnt drive under its own power (short tranny and short t case). Leaking tells us that you either dinged the tranny seal or its pretty worn. Dorp the case and replace the tranny seal.

02-08-2010, 06:25 PM	#6
TheSharkster Junior Member Grand Rookie Join Date: Sep 2009 Location: Pennsylvania Posts: 17	Sounds logical to me also... but... why doesn't the tranny seal leak with the 249 installed? That's what gets me... I put the 231 in yesterday and it leaked like hell... put the 249 back in and it didnt leak... what do you think guys? Could the seal be that bad as to not leak on the 249? That's what gets me... Could the input shafts be at different thickness? I do not have a micrometer to check this... You guys are great... keep the info flowin...

02-09-2010, 01:37 AM	#8
TheSharkster Junior Member Grand Rookie Join Date: Sep 2009 Location: Pennsylvania Posts: 17	So the 231 input shaft is just a tad short, I understand. Do you think that I can use the 249 input shaft to replace the one in the 231? I had just read a writeup on this subject on another sight(posted 2008) where a guy used an input shaft out of a 242 for his 231. I am hoping that I can use the one I already have.

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