engine swap help TJ 97 - 03 4.0 litre

Estonian

Member
Joined
Oct 25, 2008
Location
Raleigh/Garner
ok, so my 97 TJ 2.5 4 cyl engine AND tranny are trying to retire after many many hard miles on it. I just purchased a rolled over 03 wrangler with the 4.0 5-speed with only 27xxx miles on it for a low price and want to swap the 4.0 into my 97 TJ. I have the WHOLE donor jeep and it still runs fine just the cosmetics of the jeep are real bad :) now the question is that does the 03 wiring harness differ from the 97 ? meaning that is it a plug and play under the dashboard? i know i have to swap over everything engine,tranny,tcase,ecu,harness and all which is not a problem but i just wanted to make sure it was not too much work to make the guages work under the dash without toooooo much headaches. i know some of you will tell me to just sell the 97 tj and buy a new one with the 4.0 already in it but the reason i want to do the swap is because my 97 is in perfect condition inside and out with ALOT of work already done to it (axles,gear,lift, etc,...) and if anyone knows of any curveballs i will be running into with the difference in the two jeeps. (97 2.5 current - 03 donor 4.0 ) would be greatly appreciated. thanks
 
i also have the SYE kit in the t-case on the 4 cyl. Can i take that out and put it in the 4.0 t-case? or is it a different spline count on the SYE part it self. i know the 2.5 is 21 and 4.0 is 23 but that shouldn't matter on the SYE kit right?
 
1997 is not compatible with 2003. If your 97 were a 4.0L from the factory it would be no problem. You'll need to, at the very least, swap over the engine bay harness and computer from the 2003 to the 1997. 1996-newer runs OBDII, 2000-newer runs OBDII series II, which is basically a distributorless igniton. I doubt anything in the 1997 dash is going to be plug and play with the 2003 electronics.

I wouldn't consider this swap but there are two "easy" routes to take as I see it.

1.) Swap over all of the 2003's under-dash and engine bay wiring and electronics over to the 1997 along with the drivetrain.

2.) Swap over your 1997 tub and associated body parts over to the 2003 rolling chassis.

Not sure on the S.Y.E. Contact the manufacturer and ask them. Since they made the product, they should be a good source for information on their product.

Chris
 
ok, i actually ended up selling the 03 rolled wrangler, and purchased a 97 wrangler 4.0 ax15, sport model for cheaper than i sold the 03 jeep for. so the swap starts this weekend. I talked to a guy at 4wheel drive on Glenwood ave. here in Raleigh and he sayd that the SYE was interchangeable between the 4 cyl and 5 cyl t-cases??? does anyone actually know this?
 
Yes the sye is interchangable between the two cases, the only difference is the 4 cylinder has a 21 spline input while the 6 cylinder has a 23 spline input, but you can swap the sye between the two cases
 
Great, thanks for the info Lee, thats one less thing i have to worry about. Also i have heard that the driveshafts will not fit anymore after the swap, since the rear will get shorter and the front will get longer? am i correct here? i just got a CV tom woods shaft and do not wish to purchase another one.
 
you will also have to relocate the engine frame mounts about 4 inches forward since the 4bangers are not in the right place. i am also doing the same swap,mine will be finished this weekend...good luck!
 
BallsDeepJeep said:
you will also have to relocate the engine frame mounts about 4 inches forward since the 4bangers are not in the right place. i am also doing the same swap,mine will be finished this weekend...good luck!
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i pulled the motor with tranny and t-case together, then i put bolted the tranny skid plate up to it and then to the frame, lowered the engine between the framerail and where ever it seemed good to me, i welded up the motor mounts i plasmad off the 4.0 frame. It sits nice and sturdy. I also welded some triangle plates on to the motor mounts to the frame. Plus i have a WHOLE donor TJ to pull off whatever i need to make things work. Did your driveshafts end up different lenghts? front longer and rear shorter????
 
Also if anybody reading this knows... what is the main differences between 97 and 06 TJ wiring under the dash, ECU, driveline, etc... i know that in 2000 it switched to distributor less system but is that the only difference? i have a chance to get a WHOLE donor 06 x-model TJ for super cheap with 30,xxx miles (rolled over BAD), and want to do this swap again in my friends 98 TJ.
 
congrats!!!! im just waiting on the welding up of the engine mounts,for my swap...glad to hear everything is going great! I read somewhere that the rear driveshaft will be shorter by a inch or so and there front longer by a inch.
 
BallsDeepJeep said:
congrats!!!! im just waiting on the welding up of the engine mounts,for my swap...glad to hear everything is going great! I read somewhere that the rear driveshaft will be shorter by a inch or so and there front longer by a inch.
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i saw your welding thread, good luck... Is the ax15 tranny shorter than the ax5? or why would the driveshafts be longer/shorter b/c the tranny mounting skid plate is still in the factory location on the frame rail and the 231J t-case is all the same lenght??? i know the motor is longer by 2 cylinders but that doesn't make the driveshafts longer... feel free to educate me b/c im very curious and dont want to buy another CV rear driveshaft now. grr
 
Well come to think of it, it was on a swap for a yj. So that could be why. what you said about it being the same makes sense to me. Have you tried bolting your drive shafts back up yet?
 
BallsDeepJeep said:
Well come to think of it, it was on a swap for a yj. So that could be why. what you said about it being the same makes sense to me. Have you tried bolting your drive shafts back up yet?
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Havent bolted the D-shaft up yet, im doing the wiring and all first. I want to get the engine to fire up and run before i go do anything else. Are you using NEW engine frame brackets or did you cut off your old ones and re-weld for your motor swap?
 
i cut them off of a 4.0l frame.. my wiring is done so all i need is to get welded up, and if that happens by tommorow i will bolt up the drive shafts and let you know about the lengths.
 
adam greene said:
would it have not been easer to justt swap ur body onto the jeep
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Yes, i was going to do that but then found out that the frame of the donor jeep was no good and bent, would have cost $1600 to stretch it back out on a frame bench, plus then you have to swap your lift over and everyother thing.
 
did you mount the tranny to the engine and then to the skid plate then lower the engine down onto the frame and weld it up? what order did you do it in cause i need to get it right the first time.
 
BallsDeepJeep said:
did you mount the tranny to the engine and then to the skid plate then lower the engine down onto the frame and weld it up? what order did you do it in cause i need to get it right the first time.
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i had the engine, tranny, t-case all hooked up as one peace hanging from my engine hoist with the 4.0 mounts on it too, then i lowered the assembly into the jeep and hooked up the skid plate to the t-case, then i bolted the skid plate onto the jeeps frame and lowered the assembly from the hoist. Now as soon as the assembly was lowered all the way down till the motor mount were hitting the frame i wiggled it around till it was in the "center ish" then i measured that it was in the center and welded up the mounts to the frame. That was it.
 
thats the same game plan i was going with too. i will wait to hook up the t- case untill after the engine is welded up because im working with a six inch lift already on the jeep and the engine tranny combo gets rather heavy. What points did you use to hoist the engine?
 
BallsDeepJeep said:
thats the same game plan i was going with too. i will wait to hook up the t- case untill after the engine is welded up because im working with a six inch lift already on the jeep and the engine tranny combo gets rather heavy. What points did you use to hoist the engine?
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i actually used a *ghetto* method to do it haha... with a chain which the end links were attached to the front manifold stud and a random bolt i bolted to the back of the block, THEN i used a ratchet strap to even out the straightness of the engine, tranny combo because it had the *lean* to it :) the engine and tranny with the t-case were heavy enough to make it sit at a perfect angle to set it all in, i also have a big lift on mine that made the whole process easyer and then harder at other times to work on.
 
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