4-Cylinder XJ Engine Swap

So I threw a rod on my 92 4-cylinder XJ, and she's been out of commission for the better part of two months now...I really miss having my Jeep.

It dawned upon me the other night, that a quick solution would be to grab a new 4-cylinder motor out of an XJ at PNP and swap it in. It'll hopefully run well enough to pass SMOG...damn CA!!! Then I'll have two years to plan something crazy like a LSX swap with a 6-speed, 4wd and a dana 44 rear axle.

I'm a bit newer to the Jeep scene, so I thought I'd ask for some tips when searching for a replacement used engine. Anything to lookout for in terms of compatibility, or are all the 2.5L 4-cylinder engines the same? I'm trying to make this as direct and trouble free as possible.

Finding 2.5Ls is tough at the scrapyard, at least around here - I only really see them in Wranglers (guess you could pull one from one of those, you'd have to swap more accessories and stuff.) You could swap a 6cyl in pretty easily though. You'll need the engine, engine mounts, transmission, transmission mounts, TCU, manifolds/exhaust/accessories, engine bay wiring harness, radiator, etc.

As for what to look for - make sure it isn't seized, check the mileage on the odometer, check how disgusting the oil is, make sure there aren't any cracks or holes in the block, check compression if you can. Compatibility, I believe any 91 through ~99 will work, not sure on the later end of that year range, I saw a '90-down YJ at the yard today (it had TBI) and a 99 TJ as well (which had a newer, more curved seeming intake, similar to the 99 intake manifold for 6cyls.) My bet would be 91 through 98.

I'd really love a 4.0L, and even thought about making the hassle more worth my while and doing that, but for the parts involved and considering JY prices here, it'd be more worth my time to find another car or a donor car that has everything I want; 4wd, 5-speed manual and the 4.0L engine. I think, given my circumstances, the direct 2.5L swap will be ideal, for now.

I'm down to do something big and exciting down the road; I'm thinking now, in terms of having a running XJ or not. I can pull a motor for $180, after core at the JY, and just drop it in and go. I bought the car in February off Lein sale, and it's now past registration and hasn't been SMOG-ed. I just gotta get it running and registered.

Motor swaps in CA are kind of a bitch, just meaning I have to do everything right and have it critiqued by the state before I get the okay...so that'll be an extended project for when I have nothing but a spacious garage and time...for now this thing is static, parked on my street.

So any 2.5L will work? If the accessories are the only difference, is it safe to assume all my accessories on my existing 2.5L will swap right over? Any tips for picking an engine out of a JY? Don't know if I'll be able to crank the motor before I pull it, because they are on the lot without batteries and, I think, without fluids.

kastein said:

Finding 2.5Ls is tough at the scrapyard, at least around here - I only really see them in Wranglers (guess you could pull one from one of those, you'd have to swap more accessories and stuff.) You could swap a 6cyl in pretty easily though. You'll need the engine, engine mounts, transmission, transmission mounts, TCU, manifolds/exhaust/accessories, engine bay wiring harness, radiator, etc.

As for what to look for - make sure it isn't seized, check the mileage on the odometer, check how disgusting the oil is, make sure there aren't any cracks or holes in the block, check compression if you can. Compatibility, I believe any 91 through ~99 will work, not sure on the later end of that year range, I saw a '90-down YJ at the yard today (it had TBI) and a 99 TJ as well (which had a newer, more curved seeming intake, similar to the 99 intake manifold for 6cyls.) My bet would be 91 through 98.

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I think you should be able to crank it over if you bring a battery and some fluids - assuming they put the drain plug back in, just top it off with oil, disconnect all the electrical stuff and ignition and fuel lines, then you can just wire the starter up (big wire from positive to starter) and battery ground, then short the small terminal (green wire on a 90 RENIX 4cyl, not sure on later years) on the starter to the large terminal and it'll crank. I have one cranking quite healthily off a large-ish lawn tractor right now.

Not sure about accessories, YJ accessories (at least some years) are going to be different but I'm 99% sure it should all bolt up. Just stay within the OBD-I and earlier OBD-II years and you should be good... really what you want to avoid is issues with head port changes i.e. make sure your manifold's ports will match up and bolt on correctly. If you can get it for the same price with or without the accessories (depends on how much the junkyard cares, and how careful they are pricing it) grab it with everything still attached and either keep the accessories as spares or sell them off after you have determined what you can and cannot use.

Completely forgot about smogging and how goofy CA is about all that stuff :doh:

kastein said:

Completely forgot about smogging and how goofy CA is about all that stuff :doh:

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Yup; it's kind of a bitch, but if you're thorough, it shouldn't be too much work. I've got other projects going on between my '79 Volvo 242 and my '90 Mazda MX-5, so it'd be nice to find a quick and cheap solution to getting my parts carrier back, running.

I'll inquire about the JY's policy's. I'll assume just look for the one with the lowest miles and least amount of oil build-up? If XJ's are anything like Volvo 200/700's there'll be a shit load of clean ones from the Cash for Clunkers deal.

Basically, I just want to find a motor for under $200 that I know I can just drop in and go...not trying to make a project out of this. hahaha. any idea what the year and model ranges for cars that are obd-i vs obd-ii? that seems like an important fact that shouldn't be overlooked.

RENIX - 87-90. You want to avoid these, the 2.5L RENIX engines were TBI at least toward the end of the run. I'm not sure if the manifold ports will match up with your 92.
OBD-I - 91-95. These should all fit AFAIK.
OBD-II - 96-later. You should compare port shapes against yours before using 99 and up from TJs and probably 99 and up from XJs too. Not sure about 98 matching, 96 and probably 97 will match most likely.

You'll want to swap all sensors that look different or have different connectors, as well - the closer to your year you get, the more likely it is that you won't have to swap things, but the further away from your year you get, the better the engine will probably be mileage and maintenance wise.

The basic block adn heads on the 86-96 are the same. The accessorys and the intakes are different. Bolt in will be 91-95 xj or yj. The yj had some different accessory locations though. I had an 84 2.5L before the current 94 4.0L. Did a lot of work over the years to it so feel free to ask away. Oh yea the 84 had a 94 yj drivetrain that I swapped in. Found it on ebay for $75.

so no worries about my exhaust manifold bolting right up, between 86-96?
different accessory locations...just a change of brackets, or blocks are differently drilled, studded? damn, maybe i can find a guy parting one out locally...i feel like a 4-cyl would be easy to find in a jy tho.

Ghost said:

The basic block adn heads on the 86-96 are the same. The accessorys and the intakes are different. Bolt in will be 91-95 xj or yj. The yj had some different accessory locations though. I had an 84 2.5L before the current 94 4.0L. Did a lot of work over the years to it so feel free to ask away. Oh yea the 84 had a 94 yj drivetrain that I swapped in. Found it on ebay for $75.

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oh, and a noob quetion for sure...what is tbi?

Mylesofsmyles said:

so no worries about my exhaust manifold bolting right up, between 86-96?
different accessory locations...just a change of brackets, or blocks are differently drilled, studded? damn, maybe i can find a guy parting one out locally...i feel like a 4-cyl would be easy to find in a jy tho.





oh, and a noob quetion for sure...what is tbi?

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Throttle body injection--TBI--one or more injectors mounted in the throttle body.

Multi-port injection--MPI--multiple injectors located in the intake.

AS far as I know there are no differences in bolt placement or anything other then different accessaries and the way they are mounted. the block and head are all the same. I know of 2 people that I helped on here convert an 84-90 xj to the mpi system. Your bassick long block is the same. I think that is the right term.

gotcha...and i can only assume the wiring harnesses and ecu's are different from tbi to mpi?

sounds like if i find another 2.5L mpi, i'll have everything between that engine and mine to get this thing running again...thanks guys!

Mylesofsmyles said:

gotcha...and i can only assume the wiring harnesses and ecu's are different from tbi to mpi?

sounds like if i find another 2.5L mpi, i'll have everything between that engine and mine to get this thing running again...thanks guys!

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If you find a yj or xj 2.5L from 91-96 it will go the easyest. Like I said I put a 94yj engine tranny and tcase in my 84 xj. I had to change both my wiring for body and engine but that was bc of the huge age difference.

Mylesofsmyles said:

Yup; it's kind of a bitch, but if you're thorough, it shouldn't be too much work. I've got other projects going on between my '79 Volvo 242 and my '90 Mazda MX-5, so it'd be nice to find a quick and cheap solution to getting my parts carrier back, running.

I'll inquire about the JY's policy's. I'll assume just look for the one with the lowest miles and least amount of oil build-up? If XJ's are anything like Volvo 200/700's there'll be a shit load of clean ones from the Cash for Clunkers deal.

Basically, I just want to find a motor for under $200 that I know I can just drop in and go...not trying to make a project out of this. hahaha. any idea what the year and model ranges for cars that are obd-i vs obd-ii? that seems like an important fact that shouldn't be overlooked.

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FYI they destroyed the motors in cash for clunkers cars

http://www.youtube.com/watch?v=OLdwnb_S32s

Ghost said:

If you find a yj or xj 2.5L from 91-96 it will go the easyest. Like I said I put a 94yj engine tranny and tcase in my 84 xj. I had to change both my wiring for body and engine but that was bc of the huge age difference.

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yep, so just trying to understand clearer when the cutoffs were from one engine type to the next...or is it not as cut and dry as other make cars? sounds like my question has been answered...91-96 is the same as mine.

just got my chilton's guides and hanes guide in the mail today!

i know these must sound like dumb questions, but this is my first jeep, and my first time working on a jeep...dunno anything yet!

I live in Cali, but thankfully my XJ is registered in a county that does not require smog (=
makes swaps that much easier.

Johnnie Walker said:

I live in Cali, but thankfully my XJ is registered in a county that does not require smog (=
makes swaps that much easier.

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what type of counties are these? i'll need property there.

so i didn't realize at first just how difficult it might be to find a 2.5L 4-cylinder jeep engine...still hunting.

this may have been answered before, but should I find a tbi 2.5l, is it as easy as switching out the intake to run my mpi?

damn, watched those videos about CFC...that's really annoying.

founda 2.5L for $200...leaks a bit of oil, was rebuilt a 100k and has 80k on it since...TBI tho...just swap my mpi intake and stuff...will this PNP?

Mylesofsmyles said:

founda 2.5L for $200...leaks a bit of oil, was rebuilt a 100k and has 80k on it since...TBI tho...just swap my mpi intake and stuff...will this PNP?

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If it is out of a jeep from 86-90 then its the same basic block. Add your stuff adn go.

'84-85 2.5L cylinder head: 8350 0675 or 8350 1411 (not sure which is which)
'86-90 2.5L cylinder head: Injected (#2403) 8350 2487 Carbed (#2405) 8350 2488
-- the TB injected head was superceded by 3300 7115 (same as '91-98 MPI) while the carbed head was superceded by 5302 0183 (same as '91-98 Carbed)
'91-98 2.5L cylinder head: Injected (unknown casting number) 3300 7115 Carbed (unknown casting number, only used on US vehicles till 93 and export till 96) 5302 0183
'99 2.5L cylinder head: Injected (unknown casting number) 3300 7115AB which indicates that it's just a revised version of the earlier 3300 7115 head

What year did the donor motor come from? Based off what I just found you should be A-OK as long as it's in the 86-99 range, I can't find any cross ref or superceded numbers for the 84-85 heads but you probably aren't looking at an engine that old anyways. There apparently weren't any 2.5L 00s or 01s so that's no concern.

EDIT - The only thing I would worry about is sensors - I know on a '90 4cyl there is no knock sensor, while on 89 (?) and earlier there is and it's mounted near the front, and I'm pretty sure 91 and later there is no knock sensor. If the hole for the knock sensor goes through the block into an oil gallery or something you should simply get the sensor with the engine and leave it disconnected as a dummy plug to fill the hole. You may also want to transfer your valve cover since the 90 and maybe later valve covers were plastic, I think the 92 was metal but I'm not sure. Also the RMS on a 2.5 is a one-piece so you should likely replace it before you install the engine just to keep from having to drop the tranny later.