2.5 to 4.2 engine swap
#1
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Year: 1999
Model: Cherokee
Engine: 4.0 Straight Six
2.5 to 4.2 engine swap
Right now Im gathering the money to buy a 88 MJ with a 2.5 5 speed 4x4 with a thrown rod. My dad has a rusted out 88 or 89 YJ with a 4.2 and 5 speed. Does anyone know if I could swap the engine and transmission out of the YJ into the MJ or would it be better to find a 2.5 and replace the engine?
Ive heard to swap a 4.0 into some Comanches you have to modify the firewall, and if I remember right the 4.2 is very similar to a 4.0. Yes I know the 5 speed out of the YJ is the "crappy" one. Its free until I can find an ax 15.
Ive heard to swap a 4.0 into some Comanches you have to modify the firewall, and if I remember right the 4.2 is very similar to a 4.0. Yes I know the 5 speed out of the YJ is the "crappy" one. Its free until I can find an ax 15.
#2
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Year: 1988
Model: Cherokee
Engine: 4.0
The 4.0 should fit just fine in your MJ but you will be making quite a few changes. The firewall should fit the 4.0 just fine...and most likely the 4.2 instead. I don't know enough about the 4.2 to know how it is different from the 4.0, aside from displacement.
#3
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Year: 1989
Model: Cherokee
Engine: 4.0L I6
Sell/junk the 4.2L And swap in a SBC or 4.0L. Easy and better than 4.2L
88 already has the larger engine bay/modified firewall. So, other than some wiring, the 4.0L should be plug n pray.
88 already has the larger engine bay/modified firewall. So, other than some wiring, the 4.0L should be plug n pray.
#4
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Yeah the 87 and back xj/mj had the smaller engine bay,The 88 and newer had the larger engine bay and came with the 4.0 stock as a option.Like said go 4.0 or v8 anything else wouldn't be worth the time of the swap.
#5
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87 and up, not 88. 86 is the only year the 4.0 wasn't an option.
#6
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Year: 1999
Model: Cherokee
Engine: 4.0 Straight Six
Is the 4.2 really that bad? I remember when the YJ was running before the frame really went bad, there wasn't much it wouldn't do. It's carbed so I figure it doesn't have all the electronics to worry about making it a fairly easy swap. If it'll fit.
Main reason I ask is that the 4.2 is free. Another engine and transmission isn't. I know it won't be my 4.0 ho.
Main reason I ask is that the 4.2 is free. Another engine and transmission isn't. I know it won't be my 4.0 ho.
#7
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4.2 is a solid motor but most people here aren't familiar with it. I wouldn't hesitate to swap one in over a 4 banger if I had one laying around.
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#8
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Year: 1999
Model: Cherokee
Engine: 4.0 Straight Six
Ive been looking at upgrading a 4.2. Ive decided if the 2.5 is completely shot. Im going for the 4.2(its supposed to have optimum torque around 2500 rpm instead of the 4.0 at 4000 or so.) Plus its free, and unique.
According to the guy with the MJ. The 2.5 does still run, I thought a thrown rod normally disabled the engine but I guess I can figure it out, either way Ill be happy.
According to the guy with the MJ. The 2.5 does still run, I thought a thrown rod normally disabled the engine but I guess I can figure it out, either way Ill be happy.
#10
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Year: 1996
Model: Cherokee (XJ)
Engine: 4.Slow
Is the 4.2 really that bad? I remember when the YJ was running before the frame really went bad, there wasn't much it wouldn't do. It's carbed so I figure it doesn't have all the electronics to worry about making it a fairly easy swap. If it'll fit.
Main reason I ask is that the 4.2 is free. Another engine and transmission isn't. I know it won't be my 4.0 ho.
Main reason I ask is that the 4.2 is free. Another engine and transmission isn't. I know it won't be my 4.0 ho.
#11
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Year: 1999
Model: Cherokee
Engine: 4.0 Straight Six
If the 2.5 is repairable with basic skills I have, I'll get it fixed. Otherwise it's been like 3 years since the 4.2 ran. But it shouldn't be too much of an issue.
#12
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Year: 1996
Model: Cherokee (XJ)
Engine: 4.Slow
I'm rebuilding my 2.5L with a 2.9L stroker kit and cam. It is fairly easy to work on and the price of all components was no more than a stock rebuild kit.
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