luckycamper

Hey man welcome to the club. I’m a little over a year into owning my own ‘86 w/ the 2.5 so I’ll drop my 2¢. I’ve owned a few 4.0 xjs in the past so naturally I planned on doing that swap but after extensive research I scratched that idea immediately. It is not just a simple swap. A couple main reasons being 1)86 is the odd year so one effect of that is smaller engine bay—you’d have to beat the firewall in to accommodate the larger block, 2) the stock trans won’t hold up so you’d effectively have to replace the whole driveline, 3) new radiator mounts have to be fabricated to accommodate the 4.0 radiator. I could go on and on but unless you personally have the space, time, desire, and capacity to do it yourself, it’ll be costly. If you do the research and are still interested I’d say the way to go about it is to score a donor xj w the drivetrain you want. Personally if I really wanted an mj w the 4.0 Id just save up and get one. I chose to stay w the 2.5, at least for now. It’s not a race truck by any means but riding around town and in the mountains it’s fine. Keep in mind if you lift it and throw big tires on it, you’re going to lose a little speed and power. Check out the other 2.5 builds on the site and see what they’ve done.

Challenging but not impossible...if I lived in a city, I would've already done that. Over the past 8 months I've called around and haven't found a shop that was able or willing to do it. Good idea. Hmm, I'll look into this and what all I'd need to replace, besides the engine, to make it happen. Would just have to find one locally that I could verify that it runs.

I'll give them a call though the issue is still that I don't have the space to do any big work myself. So unless I can confirm it is in good running order, it's too big of a risk. I may still try to see if I can find another running engine with some life left in it...

What would one need in order to fit a later 2.5 into a remix comanche? I'm assuming you'd need the harness and ecu. What else would change/what else would one need? Would the sensors be the same? I'm curious about doing this and it would be a huge help to hear from someone who's done it.

Yes it definitely is more money then I’d prefer to spend but I don’t see another option besides outright selling my truck. I don’t have the space to do any major work so I’m quite limited in that capacity. I’ve researched swapping in a 4.0, as that was my original plan, but there’s a lot more to it than banging away at the firewall.

Hey Eagle, just to clarify, since I’m planning on swapping out my instrument cluster too. -What is the reason to replace temp/oil pressure sensor? Is it bc we’d have to get an XJ temp and oil pressure sensor? -and do you mean we’d have to get an XJ speedometer cable too?

Hey @cruiser54 That was one of my initial ideas but I don’t have the space right now to necessarily take that on. I can get away with doing a little work over the wknd but nothing too big. If I had a garage it’d be a different story.

Hey comanche club, last year my 2.5 went kaput. After weighing my options, I've decided the most straight forward move is to swap in a remanned. So I have some questions for you 2.5 guys. First, this is the engine I'm planning on going with: https://www.jegs.com/i/ATK-Engines/059/DA27/10002/-1?year=1986&make=JEEP&model=COMANCHE&submodel=CUSTOM&engine=L4+(+2.5L+%2F+150+)# My questions are: 1) What other parts would yall suggest to replace when I do the swap? -I'm thinking oil/filter, belts, hoses, possibly aluminum valve cover if I can get my hands on one. -Any gaskets?(https://www.quadratec.com/products/51100_04.htm) Sensors? Really just talk to me like a noob because I haven't done an engine swap before and I'm not sure what other parts should accompany the swap beyond what I mentioned (*I'll be helping my mechanic friend with the work). 2) Any tips or things to be aware of that might hang things up? -I have all the manuals and it seems straight forward, but of course there's always a few fun little surprises! 3) Does anyone know the exact size of the ISA screw (the screw that plugs into the isa and controls the idle)? 4) Is there anything else to consider? Does this seem like the best option?

Meant to add my truck to the registry long ago! 2.5, 5speed, sitting on dana 30/35. Bought last September here in Montana; currently residing in Missoula. Garaged atm until I get around to bringing engine back to life.

so there is a god. Anyone have a good hypothesis on where they’d actually be sold online? carparts?

I think I will. I found a spot to park it for the winter so she will live. In regards to your project, I’ve seem a few comanches pop up on cL and fb marketplace that would surely suit your needs. I’d peek around if you haven’t already. This is a good idea, I’ll be looking into it.

My response was more to the guys that have been helping me out to trouble shoot my rig, etc. As of right now, I’m not keen on selling…prob going to try and wait out winter and continue with a planned motor swap, now that I have a place to store the truck. But I will keep you updated if things change if you’d like?

Final update. Have determined at least two burnt valves so pretty much dead in the water rn. I live in apts at the moment so I can’t necessarily store it forever. Undecided what my nxt step will be. Would like to hold onto it until I can figure what to do with it but not sure how feasible that may be. Thank you all for the assistance to this post and the contributions to this vast source of information. It has helped me immensely.

update: Took a few days to finally get to the bottom of this. No compression on cylinders 2 and 4. Only 50 on the other two. Not good news but closer to figuring this out. Tomorrow me and my buddy are going to open it up a bit more, chk the timing chain etc. Saying my prayers tonight.

interesting i will give that a look!

@eaglescout526 thx man, these pix are a big help. There is def some discrepancies in comparison to my truck. I’ll thoroughly go through the lines again and cross reference these pix tomorrow but right off the bat; the pvc valve doesn’t go directly to my airbox, there is a canister thing on the pvc air in, the two ports on the head of the tbi cover are open, the airbox has no hoses beside whats pictured inside/out, the hose I’m holding in the last picture was just sitting loose in my airbox when I first popped it open…

will do thanks!

Thoughts so far: -The day before the engine suddenly went mad, I did an oil change regular ol’ 10w30 and added some 4cylinder Restore additive (which I’ve used on i6’s before w good results). A little research uncovered that sometimes, albeit rare, it can mess w the sensors. It’s a shot in the dark for sure but I have extra oil so I’ll prob do a change tomorrow. -I’ve been leaning toward mechanical failure over vacuum leak bc of the abrupt change in performance but even though I went through pulling hoses, spraying around joint fittings and cluttered areas, etc., I do not have access to the correct tools to properly address this possibility. I assume there are leaks, due to the evidence of the previous owners work, I just don’t know if something small I missed would potentially be enough to cause such drastic effects. -It’s loud like an exhaust leak so I fear a leak in the exhaust manifold bc it seems like hell to replace. I tightened down the bolts on top but the rest seem inaccessible w/o tearing the whole intake, throttle body apart. -No blue smoke. No grey smoke. Coolant is good. -Can smell it’s running rich. -Only starts if I continuously pump the gas and keep it at high idle once started. It shakes violently and erratically. And stalls if it’s not getting gas. Though once warmed up it will idle low for a min before eventually stalling. -The screw to the isa was missing but I found one of the correct thread. The screw does not seem to affect the current performance of the engine in it’s current state. If anyone has any recommendation on what nxt step makes the most sense I’m all ears. Rn I am leaning toward a fuel/air situation causing misfire, etc. with the symptoms I’ve described. Could be a sensor issue. Could be vacuum. Kind of at a loss rn. Might get to borrow a fuel pressure gage soon so I could officially rule that out…hope to get it running soon bc it’s cold and rainy where I am and it’s not my favorite bike ride to work lol.

I checked out the positives and everything looks fine (unless there is something I missed). I’ve gone through the vacuum lines and nothing seems to be causing such a dramatic effect. I have not checked the canister, possibly I can get to it tomorrow. With that said, the diagram on my truck doesn’t exactly seem to match what I’m looking at. Idk if po did a bunch of deletes or just forgot to reattach hoses. It would be immense help if I had a few pictures of a clean detailed picture of the 2.5 engine bay to cross reference.

pipe is broken off right after the muffler and its hollowed out. I also thought maybe the cat is toast though I knock on it and don’t hear anything rattling around. Still a possibility…I might pull it out and take a look but it’s so rusted i’m afraid it’ll fall apart. (wasn’t planning on addressing it until i do an engine swap nxt spring)

hey guys, thanks for the tips. Just got home from work and will try some things in the morning. I don’t have a way to legit test vacuum rn but maybe I could get my hands on something or squirt some carb cleaner around. I’ll try to do a more thorough check tomorrow of the vacuum lines tomorrow but truth be told, there are things just hanging disconnected since I bought it and even w the diagram it’s not easy to make sense of. I’ll also try to go through more of the electrical and see what turns up. the smoke coming up from under the manifold still concerns me but I’ll try to hunt down any vacuum leaks over the nxt couple days and report back

There’s smoke coming out from below the manifold so a leaky gasket or cracked manifold has entered into the realm of possibilities. Is there a way to verify this before I tear everything apart? -coolant and oil seem fine will do

have not cleaned the positive cables yet but i plan too.

wow, I can’t believe it’s been running w/o that screw the whole time! I wish I had a couple pictures of what the engine bay is supposed to look like, to compare. Battery light has been on for over a month. I’ve been refreshing the grounds to try and get to the bottom of it but so far no change. Has still been driving fine and the alternator and battery are putting out just fine when I test. Any idea what size screw that is? or how to find out? Perhaps i could pick it up at a hardware store

After I got home, I popped the hood and there was a little smoke coming from the exhaust manifold. Idk yet if this is a cause of my troubles or just an effect of something else and driving it the 15min back home. My experience driving it home was that it would want to die as soon as i lifted off the gas/felt like it was about to lose all power. To keep it from stalling I’d crush the pedal all the way down and it would slowly catch up, low idle speed.