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Old 07-01-2013, 04:08 PM   #1
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2.5 or 4.0 swap?

Hi, forum. It finally happened, maybe a little too soon, but the lil four banger finally went caput . I need to pull the motor and my options are rebuild, straight swap or 4.0 swap. Budget and time wise logicaly, straight swap is the way to go but the crazy little mechanic in my head says be bold and go for the 4.0. All of this is based on the overall condition of the origional motor. I know I broke a piston rod I just don't know the damage to the cylinder wall since I haven't had the time to pull it apart yet. What do you guys think?

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Old 07-01-2013, 08:47 PM   #2
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If I understand correctly the 4.0 swap is a major change because nothing works, e.g. engine mounts, bell housing, etc.

A replacement 2.5 liter should be pretty cheap and easy to find given the number of them being pulled to do conversions.

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Old 07-02-2013, 12:20 AM   #3
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Quote:
Originally Posted by WICruiser View Post
If I understand correctly the 4.0 swap is a major change because nothing works, e.g. engine mounts, bell housing, etc.

A replacement 2.5 liter should be pretty cheap and easy to find given the number of them being pulled to do conversions.
Well, the idea of the 4.0 swap was find a donor vehicle and remove the whole drive train do some cutting and welding and install it. However I do see your point. I'm just scared to find another 2.5 and end up with the same problem a few months from now.
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Old 07-02-2013, 12:30 AM   #4
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It's not as bad as they say just did this to mine. You must use your 2.5 wiring harness and wire in injectors 5 & 6 it not bad at all and add some wire to your oil sending plug and coil plug. You can use the wires from the 4.0 harness and you will need the 4.0 ECM you will use that. The map sensor plug will reach when or if you take the tape and wiring cover off. I think the hardest parts was squaring the engine for the new motor mounts
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Old 07-02-2013, 12:35 AM   #5
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Old 07-02-2013, 12:57 AM   #6
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It's not as bad as they say just did this to mine. You must use your 2.5 wiring harness and wire in injectors 5 & 6 it not bad at all and add some wire to your oil sending plug and coil plug. You can use the wires from the 4.0 harness and you will need the 4.0 ECM you will use that. The map sensor plug will reach when or if you take the tape and wiring cover off. I think the hardest parts was squaring the engine for the new motor mounts
Thanks for the info Maverick. Still got some time before I make a decision. Just gathering info before deciding. Is there a lot of welding involved? I need a new welder and have to factor that into the cost.
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Old 07-02-2013, 01:05 AM   #7
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Just the motor mounts. You may have to have drive shafts made up depends on what axles you have in it. I used my 2.5 shafts and had them cut down to fit. If I would have known that I was to use the 2.5 wiring harness I would have left it in but I didn't and pulled it all out it wasn't to bad but the fuel pump wirer wasn't funny at all so I would just leave it all in if you can
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Old 07-02-2013, 01:16 AM   #8
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Just the motor mounts. You may have to have drive shafts made up depends on what axles you have in it. I used my 2.5 shafts and had them cut down to fit. If I would have known that I was to use the 2.5 wiring harness I would have left it in but I didn't and pulled it all out it wasn't to bad but the fuel pump wirer wasn't funny at all so I would just leave it all in if you can
OK, this is great info I will decide in a few weeks on what to do after I pull apart the motor. I'm sure I'll have to swap the tranny too. Am I right?
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Old 07-02-2013, 02:35 AM   #9
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If you go with the 4.0 then yes and the transfer case as well
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Old 07-02-2013, 02:46 AM   #10
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Oh. By the way you will need to switch fuel line the 2.5 are to short. On my 93 it had the plastic clip that held it on take them off and the 4.0 line will clip wright on. There just below the driver set on the frame. Easy to do I freaked out at first
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Old 07-13-2013, 10:00 AM   #11
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Hey guys, sorry to intrude on this thread but that is exactly the swap I started over a year ago I am in dire need of a wiring harness (brain and all) from a 92, 93, 94, jeep wrangler that came out factory 4.0 mine will not start it keeps throwing a ignition code and I've replaced the coil, ignition coil, cam shaft sensor, and crank shaft sensor, it's not firing from the coil to the plugs any ideas ,,?
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Old 07-13-2013, 10:53 AM   #12
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How many miles you get out of the 2.5 and how much wheeling where you doing. Getting a 95 with 2.5 with 160K but not planning on keeping the 2.5 but for the next 2-3 yrs or so I will be keeping it in. Buying from my cousin and she has had it for about 10 years and didn't wheel it.
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Old 07-13-2013, 10:51 PM   #13
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Check to see if you got voltage to the coil if not could be a bad wire or you can add a wire from the battery to see if that get it got just to see if that the problem. If that work replace the coil wire don't leave it hook to the battery it will burn up the coil when the jeep not running
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Old 07-13-2013, 10:55 PM   #14
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I got 126000 on the 2.5 I pulled and it was still going strong just wanted more hwy speed. The 2.5 will do fine on off roadn never had any problem never really did any crazy sh@t like some people do fun to watch lol
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Old 08-06-2013, 03:05 PM   #15
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Ok, so I finally got around to breaking down the motor and found the bottom end to be just fine. I checked for worn rings and scored cylinder walls and they looked to be in really good shape. I even put fluid in each of the cylinders and waited 5-10 min and none of them leaked. So the problem is actually in the head. This was confirmed by my local machine shop who told me the cylinder head was cracked in half causing the low psi in the #2 cylinder. He said he can get a remanufactured replacement here in a day for around $600. He also said thant the majority of the time someone brings one of these heads to him it's the same story. Is this a fair praice for a reman head or shoud I take my chances at a junk yard?
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Old 08-06-2013, 07:26 PM   #16
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600 seems way to much, heck you can get a reman 4.0 head for around three. Check on ebay there are several places, they send you the reman part and you send them your old one as a core. Some of them clearly state in their ad that it doesnt matter if the core is cracked, busted or warped. That and a gasket set, new fluids and a tune up you'll be done for under 600. Don't forget NEW HEADBOLTS.
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Old 09-10-2013, 01:53 PM   #17
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Well, guys. I ended up buying a reman. cylinder head with no luck on fixing the true problem. So I decided on a full bottom end rebuild and here is where i am now.
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Old 09-10-2013, 02:00 PM   #18
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I love the design of these jeeps, mainly this little four banger. It is so simple. I had the engine pulled and broken down to the bare block in about 4.5 hours.
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Old 09-10-2013, 02:03 PM   #19
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It wasn't till I did this that I found what I believe to be the true causes of my problems.
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Old 09-10-2013, 02:05 PM   #20
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What you are looking at is a broken piston ring on the #2 piston and a crack on piston#3.
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Old 09-10-2013, 02:14 PM   #21
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After the motor went to the machine shop i decided to clean up the engine bay here's some before and afters. It is amazing what a wire brush, an angle grinder, sandpaper, and a little paint can do.
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Old 09-10-2013, 02:17 PM   #22
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And after a little bit of elbow grease.
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Old 09-10-2013, 02:30 PM   #23
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The idea is a mini budget rebuild/refurb of the vehicle. Planning on a paint job and black wheels with 31" tires keeping the hight it has. It will be a dd for my wife. Tranny is perfect and there are no leaks so a general clean up is what I am after to make it look good.
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Old 09-14-2013, 01:08 AM   #24
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Looking good under the hood.
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Old 09-14-2013, 04:41 AM   #25
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That's a sexy engine bay. Wish mine looked that good. Good to know when I finally pull my 2.5.
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Old 09-19-2013, 05:52 PM   #26
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Ok, I got my engine back from the machine shop along with my Master rebuild kit from northernautoparts.com. I ended up spending the better part of the last two days cleaning, degreasing, scrubbing, sanding, and painting almost every part of the engine here's how they came out.tobucket.com/albums/q611/walkiemandu/20130918_163715_zps0a4f9d9f.jpg[/IMG]
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Old 09-19-2013, 05:55 PM   #27
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Old 09-19-2013, 05:58 PM   #28
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In case noone noticed. Yes, my wife is a Green Bay Packer fan. I thought it would be cool to suprise her with her favorite team's colors under the hood.
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Old 09-19-2013, 09:21 PM   #29
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I think I just feel in love with your motor..."or wife's".... I thought you were going with John Deere instead of green bay but still bad ass
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Old 09-20-2013, 05:50 AM   #30
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Looks great - what did the project cost so far? For the machine shop, rebuild kit, etc

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