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Engine Swap


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Hello I'm new to this Forum and I own a 1987 Jeep Comanche MJ with the 2.5 4 Cylinder 5 speed transmission with 200,000+ miles on it. I was wanting to put a 2.8 V6 in it and keep the 5 speed manual in it, i was just wondering if i could keep the same bell housing for the 2.5 or would i have to find a bell housing to fit the 2.8 V6 

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just because it's free, doesn't mean it automatically a good idea.  the 2.8 may share its transmission pattern, but shares little else with the 2.5.  is it complete with exhaust, accessories, carb, wiring, etc? 

try the classifieds here or try car-part.com for junkyard searches.  the 2.5 has remained pretty much the same for 20 years so there's gotta be a decent head out there for ya. 

 

out of curiosity, what precisely has gone wrong with the 2.5? 

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The head is warped and somebody went and tried to tap one of the valve cover bolts out and they ended up snapping the the tap off inside the head and I tried everything to get it out and can't manage to get it out... And I was going g with the 2.8 cause like I said it was laying around in the garage and I couldn't find a head for the 2.5 for a reasonable price

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If you search enough jeep forums you'll find a cheap complete 2.5 to either swap in or use as a donor. I bought a complete running spare engine for $100 off the classifieds here. There's always someone doing a swap and selling one off. The 2.5 is a much better engine than that 2.8. The 2.8 isn't worth the time and energy its going to take to make it work in your Comanche. Just keep searching for what's needed to fix the 2.5. You'll be much happier in the end.

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If you search enough jeep forums you'll find a cheap complete 2.5 to either swap in or use as a donor. I bought a complete running spare engine for $100 off the classifieds here. There's always someone doing a swap and selling one off. The 2.5 is a much better engine than that 2.8. The 2.8 isn't worth the time and energy its going to take to make it work in your Comanche. Just keep searching for what's needed to fix the 2.5. You'll be much happier in the end.

This.

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any jeep 84-02 (I think, can't remember what the last year was for the 2.5) can donate it's head.  I would post up some wanted ads in the big cherokee/wrangler jeep forums. :thumbsup: Heck, i think some years of dakota can even work. :D

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My '88 Dakota was a 2.2 Dodge motor. After they that used the 2.5l version of that same engine for a few years. Sometime in the mid 90's (96?) the Dakota moved to the jeep 2.5 but switched to the 2.4 after a couple of years. I don't know about the swap potential from a Dakota but make sure it is the later jeep engine and not the earlier Dodge 2.5L

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The AMC 2.5L (Chrysler continued its use but it was an AMC designed motor as was the 4.0L) was used from 84-02.

The only difference of concern was the earlier 84-85 heads used a 7/16" head bolt as opposed to the 86+ 1/2" bolts.

It was the standard motor for the Dakota from 96-02, the MJ/TJ/YJ/XJ from 84-02.

Other that the head bolt change mentioned the engine was more or less unchanged in it's entire production run. The changes made were in fuel delivery which were external and interchangeable to the motor (carb, TBI, MPFI).

There are also a number of parts you can snag from a 4.0L to complete the 2.5 as well as the 4.0L was designed off the 2.5L.

As far as motor compatability goes ... the 2.5 has less issues with that than the 4.0 does. In essence if looked at from a block/head swap ... An AMC 2.5 is a 2.5 irregardless of which vehicle it came from.

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The 2.8 is a downgrade in almost every way. You will be disappointed if you go through with the swap. It's a weak engine with poor fuel economy and problems keeping the knocks and oil in. Not discouraging you but retaining the stock engine is a much better idea, even if it costs more at first.

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Sell the 2.8 and use that money towards a new/ used head . You'll have more money in the swap then fixing the head .

^^^ This.

 

The 2.8L was a horrible, horrible engine. The 2.5L is a much better and much more reliable power plant. It is absolutely NOT worth the effort of converting from the 2.5L to a 2.8L. Think of everything you'll have to replace if you swap. The 2.5L is fuel injected, the 2.8L is carbureted -- you'll need a new fuel pump (lower pressure). You'll need new motor mounts. You'll need a new exhaust system. There will be a myriad of little things that will have to be changed as you go along.

 

Don't do it.

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The 2.8L was like Jeeps version of a birth defect.

Everyone will accept that it is there, and you will accommodate the issues of it's existence ... But it's not something you want to add into the equation just because it's available.

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I have all the wiring carb accessories exhaust... I have everything for the motor I even have the transmission that was with the motor from when it was in another jeep

It's still a piece of crap.

 

Don't do it. You'll be sorry if you do.

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