My 2.5 to 4.0 TJ swap

[KTM Mike]

I have finally gotten elbow deep in my 2.5 to 4.0 swap in my 97 TJ! This project will certainly drag on for ever knowing how my pace is on such things...and limited time, but I thought I might start a thread here and update occasionally as work progresses.

A bit of back ground:

Recipient: 1997 TJ 2.5 5 speed. About 132,000 miles on it - cylinder #4 decided to take a crap shortly after I told my 17 year old son the Jeep was his to drive. Took us quite a while to decide what to do - but finally decided "no replacement for displacement!"

Engine to go in: From a 98 Grand Cherokee - already pulled. Will need to use various parts from my 92 Cherokee donor to finish it off. A LOT of people told us "go V-8" - but I felt more comfortable with the 4.0 can keep all my stock guages - wont need to worry about busting axles with to much power etc.

ECM - Plan to use the PCM that came with the Grand. Pretty sure it is "non SKIM/SMART Key enabled - so should be safe (UPDATE: ended up finding out the 98 Grand's PCM had a factory alarm system - NOT the SKIM/SMART Key stuff, but a factory alarm that would shut down the engine after a couple seconds. Ended up going with a PCM from a 97 XJ 4.0 I will post more details when I finish this write up)

Wiring Harness - just bought one from a 98 Cherokee - thought that might help as I plan to use an AW4 tranny from a Cherokee. (update - ended up finding one from a 97 4.0 TJ - could not find a TJ harness before. I did determine the XJ harness could be adapted to work though)

Tranny: will use an AW4 from a 92 Cherokee donor I bought for tranny only. Turns out the engine started right up for us (seller said it did not run...) It came without a T-case, but otherwise complete. Plan to part out the rest of the vehicle - though may keep the engine, harness and ECM for future use (I have another son that needs to do a project like this...can you say Stroker?)

Transfer case - got a 23 spline T-case from a TJ sitting in the garage already.

Budget - LIMITED! (VERY)...trying to do all this for under $1,000. I think I just might pull it off, particularly after I net out proceeds from parting out the XJ. So far, so good...

Head Mechanic, and his helper: Me and my 17 yr. old son. I am far from as skilled of a wrench as I am certain 95% of the people on this board are - very limited experience with this sort of work. Last time I did anything like this was (ug...hate to say this) 27 years ago, when I was the same age my son is now, working on a 67 Mustang! I am quite comfy wrenching on motorcycles - can do a crank up rebuild in my sleep practically (I think I did that once actually - an all nighter the night before a race...) - large scale auto stuff - dont do much of.

Our work to date has been pretty limited - got the engine out of the TJ last night, got one motor mount cut out - then decided to get the engine and tranny out of the donor Cherokee - so started on that late this afternoon.

One trouble spot so far was removing the !@#$!!!!! bolts that hold the skid plate on! Had to go buy a hotter torch to get bolts heated up enough we could move them - busted two allen wrenchs before we got the hot torch (MAPP and Oxygen). Next trouble spot was getting the T-case linkages off - I am sure we missed some easy way - ended up removing the linkage bracket - (the one that bolts to side of the tranny tunnel) - but had a hell of a time with that - rust and Michigan corrosion is the enemy of fasteners!

On the tranny donor, at first considered dropping tranny only, then decided we might as well pull the engine - wether we keep it or not, sooner or later it will be coming out - so now is the time. Chances are it will all be out tomorrow night (Saturday 12/29) depending on how much time I have to spend on other projects (like plowing all this stupid snow coming down right now!)

I will post some pics tomorrow - stayed tuned for a bunch of stupid questions once I get further into this project!

[KTM Mike]

Decided to post some pics now...


We took the fenders off to make access a bit easier. Well worth the bit of time it took to do this - you can get to every thing so easily. Oh - in case any one wonders why the valve cover is off to pull an engine...its not..it was off as we had been messing around with leak down tests etc. trying to decide what the deal was with the motor.

http://www.michiganwheelers.com/forums/imagehosting/2384775d68d45b4e.jpg

Here it is with front grill and radiator out - boy that motor looks puny in there!

http://www.michiganwheelers.com/forums/imagehosting/2384775d703dbc10.jpg

Here is the 4 banger emerging from it's home for the last 10 years...

http://www.michiganwheelers.com/forums/imagehosting/2384775d68d758e9.jpg

And at last - the 4 banger is no more!:

http://www.michiganwheelers.com/forums/imagehosting/2384775d749e3c0c.jpg


Engine bay wide open... had the right motor mount cut out in this pic - but set it back in place for the picture. We plan to get things all cleaned up purty like before we are all done...so we can get it muddy.

http://www.michiganwheelers.com/forums/imagehosting/2384775d703f36f7.jpg

Here is the 4.0 we will be putting in. We have not cleaned it up yet, but will do so before it goes in.

http://www.michiganwheelers.com/forums/imagehosting/2384775d703c3d43.jpg


Here is our Tranny donor before shot - (let me know if you need any XJ parts!)

http://www.michiganwheelers.com/forums/imagehosting/2384775d68d5de00.jpg

And here is our tranny donor with the front grill, radiator etc. removed

http://www.michiganwheelers.com/forums/imagehosting/2384775d988ba439.jpg

Hopefully before next year - the engine bay of the XJ will be empty....

[sglide]

good start
i look forward to seeing this progress as im planning to do the same swop:thumbsup:

[Quagmire]

I hate to burst your bubble but you are gonna have some accessory drive clearance issues

[KTM Mike]

I hate to burst your bubble but you are gonna have some accessory drive clearance issues

Ok...burst away....dont just drop a bomb without explaining... :wtf:

FWIW - I am not using the XJ motor - I know the fan is off center on the XJ. I am using a motor out of a 98 Grand which has fan in center - and as I understand it, if I cant use existing brackets, can bolt up TJ brackets. Where specifically are the clearance issues?

After a few hours of snow plowing and other stuff, got back on removing the XJ motor today.

Here it is coming out...

http://www.michiganwheelers.com/forums/imagehosting/2384776e9baf18c2.jpg


And another engineless Jeep is now setting in the driveway. Good thing I dont have any neighbors!

http://www.michiganwheelers.com/forums/imagehosting/2384776e9bb15d1f.jpg

[Grandman]

Looks to me like your doing ok on the wrenching :thumbsup:

[Maverick]

dang i have the same color XJ, i need a passenger side fender and a front clip, radiator also, if you can spare that stuff.

good luck on the swap

[KTM Mike]

Maverick - check your PMs!

[Quagmire]

Ok well first off an Xj motor will work I have one in my TJ The Issue you will run into is the Alternator will not clear the inner fender in its current location.
Hmm after looking at the picture it may clear but I cant see the accessory drive to distinguish if it was the same as the TJ's of that era.

[KTM Mike]

Quag - thanks. What's the fix for the alternator then? TJ Alternator bracket? I am using a ZJ motor though - not sure if the Alternator is located same as XJ or not - off hand I think it is.

[KTM Mike]

It has been a while since I last updated this thread. We have been chipping away at this project, a little bit here and there, and most recently made some big headway. Before I go into this update, I did want to post some links to other write ups online which have been VERY helpful in figuring out how to do all this stuff. Without the info in these links, I know I would not of figured out how to do all this! There is much more info elsewhere that I used – do some searches on the various Jeep forums!

AW4 related:

http://stu-offroad.com/engine/aw4/intro.htm
http://stu-offroad.com/engine/aw-4/aw-4-1.htm
http://www.thebassetts.us/Jeep/AW4/AW4_files/page0001.htm
http://bullsoffroad.forumup.com/about107-bullsoffroad.html
http://bullsoffroad.forumup.com/about108-bullsoffroad.html
http://bullsoffroad.forumup.com/about109-bullsoffroad.html
http://bullsoffroad.forumup.com/about110-bullsoffroad.html

Great pics of a 2.5 to 4.0 swap in a TJ:

http://www.jeepshots.com/shots/projects/4%20Liter%20Swap/


Also, for the benefit of those who might read this, and have not yet done the research on some of the bigger things to watch out for with a 2.5 to 4.0 swap, here are some quick points to keep in mind. Much of this info initially came from the links I posted above, and many hours of searching on various forums. Some of it was learned the hard way as I have been working on this project.


- You will need a 23 spline input transfer case (unless your tranny is from a pre 91 4.0)

- You will need 4.0 motor/frame brackets (the weld on part). Some guys cut the old ones out of a donor TJ. I ended up buying new ones from the Jeep Stealership. The part numbers and prices are as follows:

Right main mount (I will have to come back with part #s later)
Right “reinforcing bracket”
Left main mount
Left “reinforcing bracket”

- You can not use your AX5 tranny with the 4.0. You need to find a tranny originally paired with a 4.0 Or….you can buy adaptors to bolt up other trannys – but they are not cheap!

- You will need the ECM (the “computer”) from a 4.0. If you are doing a TJ, must be an OBDII era ECM. (ie don’t use one from a pre 96 vehicle ) Older units are ODBI – many issues to tie in gauges. Also, the ECM does not necessarily have to be from a TJ. The one I am using is from a ZJ. It would likely be a bit easier to use one from a TJ though. If you get a more recent model ECM (98 or newer), watch out for ones with the “SMART KEY/SKIM module (security system crap) enabled. If yours has this, the recipient vehicle must have the corresponding stuff underdash, and in steering column. I understand there is someway to get it to work in that case. If you don’t have the underdash/steering column stuff associated with the SKIM system – good luck! Best bet – get one without this stuff! Oh, also I understand that somewhere in the more recent years, not sure exactly when…2000 maybe? Other changes in the newer ECM’s evidently are not compatible for the sensors and gauges in slightly older, but still ODBII units. So…keep older with older, newer with newer is what it boils down to I guess.

- You will want the engine compartment wiring from a 4.0. Best if this is from a year as close as possible to your recipient engine and computer, and from a TJ 4.0. If you do this – wiring is pretty much plug and play. Unfortunately, I found it hard to find a TJ 4.0 harness at a decent price. Salvage yards often wanted over $200 for a TJ harness – more than I wanted to spend, and the majority of private sellers of TJ harnesses wanted top dollar as well. By carefully comparing connectors, and pinouts (via ALLDATADIY.com), I did determine I could use one from a XJ 4.0 – but it would take some modifications to do so. Easiest way is to get one from a TJ. Like with ECMs, keep newer with newer, older with older! I did do quite a bit of comparing of the pinouts on the ECM for a 2.5 4 cylinder vs 4.0. Virtually everything does line up the same, of course except for the 2 added cylinders and a few other things. From this I would conclude it is possible to modify a 2.5 engine harness to work. I did read a post on some forum where someone did this. Back to the “plug and play” comment. From comparing the pinouts, it does appear that all that it will take is to plug the one large ECM connector that ties in the underdash stuff that is already on my 2.5 chassis, into the 4.0 ECM, then plug in the two other ECM connectors from the new harness, then connect the other end of this 4.0 harness to all the various sensors etc. on the new engine. Pretty simple. I did eventually find a decently priced TJ 4.0 harness though.


Since the last update we have:

· Finished cutting out both motor mounts
· Finally got the proper mounts ordered from a Jeep dealer – took a few tries for them to get the right parts though.
· Cleaned up and painted the frame in the engine compartment area
· Cleaned up and painted the engine block
· Swapped the valve cover from the 92 XJ onto the motor we will use. The one on it had a dent in it.
· Installed new rear main seal, valve cover gasket, oil pan gasket on the engine.
· Made our own wiring harness to wire up the AW4 transmission.
· Ended up finally buying an actual TJ 4.0 wiring harness. Previously, absolutely could not find one anywhere (for a reasonable price at least). I did spend some time looking over the 98 XJ harness I had and determined I could make it work – but it would take some work. (if anybody wants an XJ harness, I have one to sell!)
· Tracked down a throttle body to fit. Initially I thought I would be able to use the one off the 92 XJ (the motor we plan to use did not come with one). Determined I could not, so bought one from a 98 TJ.
· Cut down the input shaft on the Transfer case to the proper length
· “Re-clocked” the transmission mount holes for the transfer case.
· Got the motor mounts welded onto the frame
· Fabricated a mount for the rear of the transmission

As time allows, I will do a more detailed write up and post some pics of the major items. below is a start at some of the more detailed info.


Transfer Case/Transmission work:

Cutting the input shaft:

I had already purchased a transfer case with a 23 spline input. It had been previously mated to a 3 speed auto tranny – so had the longer input shaft. The transmission I plan to install this on (AW4), requires a shorter input shaft. I pretty much followed the way they did it in the write ups I posted links to above. Prior to marking my cut we double and triple checked the amount to cut off by using the depth guage on my digital caliper. This confirmed the 13/16” amount as I saw referenced elsewhere. A few posts commented about other amounts to cut off, one surprisingly saying they cut the 13/16”, but found it to long, so cut off more. Based on our measurements we cut off 13/16” from the shaft using my drill motor and a cut off wheel. I placed a hose clamp in the shaft to serve as a guide to my cutting. It took a while, but went well. To help make it more likely to get a good cut, I strapped the transfer case to a work bench, and made sure it was level. I could then use the little level bubble on my drill, along with sighting along the edge of the hose clamp to keep an eye on if I was cutting it square. I had my son rotate the shaft back and forth as I kept the drill lined up. Due to the part where the clamp comes together being wider, we could not cut that part, so just worked on the remainder, got it cut, moved the clamp slightly and finished it off. We then beveled the outer edge of the shaft with a grinding stone to help avoid nicking the seal in the rear of the transmission. We were really apprehensive when it came to starting the cut – but once it was done, were pretty happy with the result.

Now was the test – setting the transfer case on the transmission. We greased the splines up, and put it together. At first, I thought we had it, as it seemed to set all the way down like it should. Then I looked closer and noticed the faces of the transmission and transfer case were not quite mating, by about 1/16 to 1/8”. We double checked the length of our shaft – no issue there. We remeasured the transmission – the 13/16” should be fine, with some room to spare. Thinking the tranny shaft might be bottoming out in the input shaft on the transfer case, as well as to verify the output shaft was not bottoming out elsewhere, we spread some red grease on the end of the output shaft, as well as the end of the transmission shaft. Still no clue! Then I noticed that the grease on the splines was pushed all the way to the bottom of the splines on the transmission shaft. The SPLINES themselves were bottoming out! A few minutes with a grinding stone on the dremel, we beveled the splines on the output shaft back a bit, cleaned the splines up with a file then reassembled the transfer case to the transmission. Perfect! The faces mated up just fine. I am glad we corrected this issue this way rather than the hassle of cutting the entire shaft shorter. Plus, I think the bevel helps make it easier to get the two cases together, as the shafts will slide on easier. I suspect the other write up I read where they had to cut off more than expected may have actually been due to the splines bottoming out.

Re-clocking the transmission:

This is another one where it appears much tougher than it actually is. (not to say it isnt nerve wracking and time consuming) More details later - and see links above!


Wiring for the Transmission Control Module (more later...fun with wires!) meanwhile see the links I posted above




Motor Mounts:

As I noted before, the frame side of the motor mounts from a 2.5 will not work with a 4.0. For the sake of clarity, there are 3 components to what is often referred to as “motor mounts”. First, there is the part that welds onto the frame. I refer to these as either “frame side of the mount”, or “frame brackets”. Then there is the part which bolts on top of the frame side of the mounts, has the rubber vibration bushing inside, which I refer to as “motor mounts”, and finally there is the part that bolts to the engine – which I refer to as the engine brackets. In various online discussions of this I have often seen people use the same or conflicting terms for each of these.

Cutting off the old frame brackets is pretty easy – just be careful to not cut to deep into your frame. I simply used a cut off wheel on a drill motor. It would be much easier to use a die grinder or angle grinder – but the drill did the trick. I made sure to grind down the left over bits of weld on the frame as part of the 4.0 mounts overlap this area, plus I wanted my end result to look as factory as possible.

Ok - that is it for now. More details and pics coming later this week with any luck (maybe tonight if i get energetic)

Mike

[KTM Mike]

We are making some progress, slow but sure. Here is a shot taken today:

http://www.dirtrider.net/forums3/attachment.php?attachmentid=14325&stc=1

Anyhow - engine is now in the frame - almost ready to start up. Actually, tried it today, but discovered a wiring snafu - clutch interlock I am hoping... (starter relay in junction box clicks, no juice to starter) Once we make sure we have the 4.0 running, we then tie in the tranny control computer wiring (AW4 uses its own separate control computer, not integrated with the ECM). ( in the attached pic - that maze of blue wires, upper left of the engine compartment - that is the AW4 wiring we have to tie in ) With any luck, tomorrow we sort out the starting issue, and fire it up!, then tackle the AW4 wiring.

It is looking like we will end up doing a SYE, and having some custom shafts made.

Oh, no issues with accessory clearance - the ZJ motor's mounting brackets for alternator etc. all seem to work out just fine.

[Mongo]

Damn that looks clean. Nice work.

[Blackjackbender]

i think you can just bypass the whole clutch thing by putting a fuse in a certin holder. look at the fuse box it should be the auto trans fuse one. not sure if thats ur problem or not.

[KTM Mike]

Thanks. It is coming together nice. I know it wont stay that clean once it is on the road and trail, but that is OK...

Blackjack - yup...I think you are correct. I found mention of it in one of those write ups I posted a link to above, as well as in the ALLDATA diagram I just looked at. Postion #20, based on that write up. tomorrow AM, I will know! Hope that is all it is.

[rodolo]

Great read:thumbsup:


I too have AW4 swap lined up, I need the front half of an xj 231 tcase to mantain the clocking. Also what have you came up with for the trans mount plate?

Are you using Stu's offroad info to help?

[KTM Mike]

Rodolo - Thanks. The clocking issue is not going to be helped with a different T-case - they are all clocked the same. Issue is with the tranny. You have to re-drill the mount holes in the tranny itself. If you look at the rear of the AW4, seems clear they designed it with the idea of the holes going in a different location due to how the casting is done. I will (eventually...) post some pics, and do more of a write up on that topic, but meanwhile, look at the Stu-Offroad write ups. A bunch of great info there, and detailed pics of the re-clocking work. It is not as hard to do as it might seem.

For tranny mount, again, Stu-offroad - or that other link I posted (forget which one...look at all of those I posted above!). Basically 6x10x 3/8" plate of steel. Drill 6 holes, Weld two studs onto it in two of those holes, VIOLA....tranny mount! The Stu-offroad site has dimensions, but actually would not be hard to figure it out on your own. To locate 4 of the holes, I simply bolted the plate to tranny, set tranny in place on skid plate, with stock mount in place on skid, mark outline of the stock mount, drill the last 4 holes accordingly.

[KennyOffroad]

Nice Build.

[KTM Mike]

Kenny - thanks. Wow.. I have been away from Michigan Wheelers for a few weeks now... i still have not went back and filled in some of the blanks in this write up. Someday...meanwhile it is racing season and the bikes are taking up to much time.

The Jeep is running well - seems to me to run a tad on the warm side (210 ish) but then I read other posts which suggest that is normal for a 4.0. that motor sure makes this jeep much more fun to drive! It pulls strong - the tranny , axle (4.10), tires (31's) gearing is great (33s would be fine as well with that gearing) - though on steep downhills and the 1/2 3 OD tranny sometimes results in to tall of a gear - that is where the manual switch modification to the AW4 would be handy.

We had issues with some drive line vibes, planned on doing some adjustable rear control arms to line up the pinion angles better, - but all the Jeep work is now on my son's nickle - so funds dictated he could only afford to do a T-case drop (we had the spacers from when the lift was first put in, but had taken them out hoping for no vibes). that cleared up the vibes through 65 mph, slight vibes start there, tolerable to 70, so we called it good.

Sglide - your help with the welding was much appreciated by the way - and Mitch loves the look with that massive stainless brush guard on it. We do need some coil spacers or something to recover the lost ride height due to weight (the combo of the 4.0 and that brush guard did it in) - but those will wait. Soon though, a rear bumper and hitch is in order so the kid can haul his own dirt bike on the trailer. Sglide - we will be in touch.

Need to get this rig out for some (mild) wheeling with some of you "experts" some time.

[feva4u]

I'll be starting my swap here shortly.........thanks for taking the time to do a writeup :thumb:

[KTM Mike]

feva - no problem. Feel free to email me if you have any questions along the way of your swap. I do need to go back and fill in some more details on our swap. So far the Jeep has been running strong - my son was out wheeling in it last weekend in some mud he found - totally coverd the jeep in muck inside and out!

One issue we have ran into is that it does run hot. For normal road use, it seems fine, and runs at the 210 that it seems most people say the 4.0 likes to run at. (some say they should run lower than that, some say 210 is where it should be) When it is really slow going off road is when it gets hot though - enough for a couple boil overs so far. We have not really worked on that issue yet, but will this winter. I suspect the added cooling load of the AW4 tranny heat is what puts it over the top. A few likely causes may be some rather simply easy fixes - like new thermostat. Or, maybe a new hi flow water pump...or we may do a larger tranny cooler - or maybe the radiator that we used simply is not enough. The TJ had an aftermarket dual core radiator in it - we may swap in a 3 core....or we may do all of the above!

We still have not really addressed the drive line vibes either, but up to 55 it really is not bad at all. Before the kid heads off to college though, some adjustable control arms should fix that. Now he is talking more and more about more lift, bigger tires etc. (you all know how that goes!) - but I am concerned that the driveline angles just may be to steep to keep the vibes down enough for highway use. If it was primarily a trail rig, I suspect it would be fine though.

[Bronco4-Play]

feva - no problem. Feel free to email me if you have any questions along the way of your swap. I do need to go back and fill in some more details on our swap. So far the Jeep has been running strong - my son was out wheeling in it last weekend in some mud he found - totally coverd the jeep in muck inside and out!

One issue we have ran into is that it does run hot. For normal road use, it seems fine, and runs at the 210 that it seems most people say the 4.0 likes to run at. (some say they should run lower than that, some say 210 is where it should be) When it is really slow going off road is when it gets hot though - enough for a couple boil overs so far. We have not really worked on that issue yet, but will this winter. I suspect the added cooling load of the AW4 tranny heat is what puts it over the top. A few likely causes may be some rather simply easy fixes - like new thermostat. Or, maybe a new hi flow water pump...or we may do a larger tranny cooler - or maybe the radiator that we used simply is not enough. The TJ had an aftermarket dual core radiator in it - we may swap in a 3 core....or we may do all of the above!

We still have not really addressed the drive line vibes either, but up to 55 it really is not bad at all. Before the kid heads off to college though, some adjustable control arms should fix that. Now he is talking more and more about more lift, bigger tires etc. (you all know how that goes!) - but I am concerned that the driveline angles just may be to steep to keep the vibes down enough for highway use. If it was primarily a trail rig, I suspect it would be fine though.

This sounds like an air flow issue to me if it stays cool at highway speed and not on trail. Fan clutch / shroud. Just my 2 cents.