oparatior Posted August 8, 2007 Share Posted August 8, 2007 Ok I think I'm going to swap my 2.5L 4 cyl for a 4.0L 6 cyl on my '86 Comanche how hard is it to do that? what will I need to do it? other than the 4.0L? can I use my existing transmission? any links or info on this would be great Link to comment Share on other sites More sharing options...
LEAD_NOT_FOLLOW Posted August 8, 2007 Share Posted August 8, 2007 Since your is an '86 your not going to get a 4.0L into it without modifications to the firewall. Link to comment Share on other sites More sharing options...
M2 CARBINE Posted August 9, 2007 Share Posted August 9, 2007 I just put a 4.0 in my 86 Xls with no problems i had to use the 4.0 motor mounts but other than that she went right in. Link to comment Share on other sites More sharing options...
Scott86mj Posted August 9, 2007 Share Posted August 9, 2007 Since your is an '86 your not going to get a 4.0L into it without modifications to the firewall. I did this conversion and had to do nothing to the firewall. Had to completely replace the header panel and radiator support, trim the area behind the headlights and replace the hood. Had to move the cross member back and shorten the drive shaft. You must have a complete parts vehicle to do this. I used a 94 xj. Not to complicated just time consuming. Motor mounts just bolt in in place of the 2.5l ones. You cannot use you exist tranny go for an aw4 if auto or ax15 if a manual. If you have any more questions just ask. Link to comment Share on other sites More sharing options...
LEAD_NOT_FOLLOW Posted August 9, 2007 Share Posted August 9, 2007 Ok call me stupid than, cause I tried to put the 4.0L into my '86 MJ and I needed a good 2-3" more clearance at the firewall for it to fit. Ended up ditching that project and put a 3.4L in instead. And trust me I know my way around doing engine swaps as I work for a world known engine tuner/builder. What exactly are you guys doing to get it to fit in? I know they changed the firewalls in '87, wonder if your guy's were late '86 builds where the firewall already changed? Link to comment Share on other sites More sharing options...
Scott86mj Posted August 9, 2007 Share Posted August 9, 2007 Yes, mine was built in oct 1986 Link to comment Share on other sites More sharing options...
JeepcoMJ Posted August 9, 2007 Share Posted August 9, 2007 some early 86 firewalls were the same ad the 85's and would not work. but a hammer solves that [rpb;e, easo;u/ Link to comment Share on other sites More sharing options...
M2 CARBINE Posted August 9, 2007 Share Posted August 9, 2007 Not to hijack your thread but Scott how did you fix that 3 inc gap between the hood and the grill panel? thanks Link to comment Share on other sites More sharing options...
JeepcoMJ Posted August 9, 2007 Share Posted August 9, 2007 Not to hijack your thread but Scott how did you fix that 3 inc gap between the hood and the grill panel? thanks what gap everything is the same. Link to comment Share on other sites More sharing options...
FxRacing282 Posted August 14, 2007 Share Posted August 14, 2007 hey I'm new to jeeps and I'm purchasing an 87 with a 2.5 and a 4spd on the floor next week and I'm wondoring EXACTLY what needs to be done to put in a 4.0. ive done engine swaps in chevys but its a little diff obviously and I'm wondoring if what components i can use that are stock. id like to keep the 4sp cause it has 4.10s and i plan on eventually running 35's (yes i know the axles won't last long) is is possible do i have to modify the tcase in anyway? Link to comment Share on other sites More sharing options...
JeepcoMJ Posted August 14, 2007 Share Posted August 14, 2007 hey I'm new to jeeps and I'm purchasing an 87 with a 2.5 and a 4spd on the floor next week and I'm wondoring EXACTLY what needs to be done to put in a 4.0. ive done engine swaps in chevys but its a little diff obviously and I'm wondoring if what components i can use that are stock. id like to keep the 4sp cause it has 4.10s and i plan on eventually running 35's (yes i know the axles won't last long) is is possible do i have to modify the tcase in anyway? you can't keep the 4 speed. it won't bolt up to the 4.0 you need a donor vehicle, it's header panel so you can fit the 4.0 engine in, and all the wiring for the 4.0. that's inside and out of the cab. then drop the 4.0 and the entire 4.0 drivetrain in the truck. Link to comment Share on other sites More sharing options...
FxRacing282 Posted August 14, 2007 Share Posted August 14, 2007 no tcase problems? would an 94 xj work? Link to comment Share on other sites More sharing options...
JeepcoMJ Posted August 14, 2007 Share Posted August 14, 2007 no tcase problems? would an 94 xj work? 94xj would work. you need to use the t-case FROM the 4.0 so that will throw out the np205 you have... the 94 is a High output so you're makin a good bargain on power with that swap :D only thing you will need to have custom made may be the rear driveshaft...but you can probably find one or yours may work. I'm not sure how different the tranny lengths are. Link to comment Share on other sites More sharing options...
FxRacing282 Posted August 14, 2007 Share Posted August 14, 2007 thanks Link to comment Share on other sites More sharing options...
JeepcoMJ Posted August 14, 2007 Share Posted August 14, 2007 welcome. don't forget you need the shift linkages for the np231 t-case from that 94 xj, you will have to pull the dash out to swap that wiring, and splice the rear tail lights back into the xj interior wiring. and you'd need to lay the 4.0 wiring down in the engine compartment before putting the engine in. it's not as hard as it sounds...it will require some drilling/welding on the header panel to put the 4.0 one in, but then after a few beers the rest of the project goes pretty smoothly...not a 1 weekend project, but can be done in a few weekends. you will also need either an inline fuel pump that puts out the correct psi for the HO 4.0 or you will need a tank off a 91 or 92 comanche (those wer high output) and the sending unit for that...the 2.5 one won't work and the cherokee one doesn't fit. Link to comment Share on other sites More sharing options...
FxRacing282 Posted August 14, 2007 Share Posted August 14, 2007 almost seems not worth it. me and a professional mechanic would take how many full days you htink? (i am pretty good with stuff like this) Link to comment Share on other sites More sharing options...
JeepcoMJ Posted August 14, 2007 Share Posted August 14, 2007 almost seems not worth it. me and a professional mechanic would take how many full days you htink? (i am pretty good with stuff like this) I've never done that swap so I can't say. I can tell you it took me approximately 16 days to stuff a camaro 3800 engine in my comanche with little help from others...and that included custom exhaust, motor mounts, AND putting in a 4.0 radiator and lower support. you're not customizing anything. so I'd say less than 2 weeks of full days. I'd say a good 4 weekends at most plus one for troubleshooting. trust me, it's worth it. Link to comment Share on other sites More sharing options...
FxRacing282 Posted August 14, 2007 Share Posted August 14, 2007 yeah well this engine ahs 260,000 on it. can i do the fuel system off the 4.0 on the 2.5 or to much pressure for the 2.5 to handle? Link to comment Share on other sites More sharing options...
JeepcoMJ Posted August 14, 2007 Share Posted August 14, 2007 yeah well this engine ahs 260,000 on it. can i do the fuel system off the 4.0 on the 2.5 or to much pressure for the 2.5 to handle? the 2.5 is tbi so no why would you even want to? Link to comment Share on other sites More sharing options...
CEThomas Posted August 14, 2007 Share Posted August 14, 2007 If you have everything you can do it in a weekend. But how much do you have to pay your professional mechanic ? If you have to pay him / her very much you may want to look into something else. Link to comment Share on other sites More sharing options...
FxRacing282 Posted August 14, 2007 Share Posted August 14, 2007 don't pay nothing he is one of the pastors at my church and we go wheelin all the time and he can help me with whatever. one weekend eh? have you done it before? Link to comment Share on other sites More sharing options...
CEThomas Posted August 14, 2007 Share Posted August 14, 2007 Yes, put a 4.0 HO into a 89. The key is to have all the parts that you need when you start and have some help. If you can have 2 helpers is a lot better. One can pull everything out inside while two pulls the 2.5 and drive train. Also helps to have the right tools Link to comment Share on other sites More sharing options...
FxRacing282 Posted August 14, 2007 Share Posted August 14, 2007 dirve train as in the whole sha-bang (axles tcase tranny) or just tranny and engine Link to comment Share on other sites More sharing options...
JeepcoMJ Posted August 14, 2007 Share Posted August 14, 2007 dirve train as in the whole sha-bang (axles tcase tranny) or just tranny and engine you don't need to swap axles. you need the ENTIRE xj chassis so that you can yank things and literally lay them directly into the comanche chassis...otherwise you'd have a mess of parts and you won't know where to put them. a first time swapper should pobably not just acquire all the parts seperately...which you technically could do...but buy a cherokee that runs and drives and has the parts you need. better yet if the cherokee is a collision or rust bucket...then you don't feel half as bad. Link to comment Share on other sites More sharing options...
FxRacing282 Posted August 14, 2007 Share Posted August 14, 2007 yeah i gotcha craigslist seems to have some i wouldnt mind using Link to comment Share on other sites More sharing options...
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