My 91yj is losing the engine battle with 178,000 original miles. I have opportunity to get the motor out of a 1998 Cherokee. They are both 4.0. I have a stick shift, the Cherokee is automatic. I am trying to find out if everything is going to fit..flywheel, fuel injection, etc..
Any info would be greatly appreciated. Looking for smooth installation or otherwise will pass on engine. I guess biggest question is will all electronic and computer hook ups be compatable???

I cannot completely answer that question. BUT I will say it should swap right over. Sometimes mopar will surprise common folks with what it is they do but that swap should go right in there.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

Are you asking if the 91 Comp. will run the 98 engine? If so no.

the 4.0L engine (that is comon to the 91 build) is rated at 350,000 miles under "normal" operating conditions. Mine has over 214,000 on it and prolly has more than that due to larger tires and the cable was unhooked for several months a couple years back. I've replaced the water pump and valve cover gasket. Other than normal maintenance like plugs and such, these are original miles, and there is plenty of life left on her. Don't assume that high miles is any indicator of a "loosing engine battle".... I've ragged mine out over the years and still do when I need to get in front of the local yuppies in their $75,000 "SUV"'s on the highway and such. She's got plenty of spur and although I don't expect to get 350,000 miles out of her, I do expect to tick past 300,000. If you haven't properly maintained your '91 YJ, it could be possible that you are in fact due for a replacement/overhaul/rebuild.... Just remember, you can't get your 15 year old MOPAR Jeep to run like a Corvette, even if you took the body and frame off a 'vet, and put your Jeep's frame and body on it, it still wouldn't run like a 'vet!

Bought it with 130 thousand on her, And I think she was pretty beat up then, I think I was a little late on any such regular maintenance helping damage done. Plan is to put motor in out of cherokee and in winter rebuild my block with somthing a little extra.... I think I should be able to get away with as long as use all oem electrics from my 91 and just use block of cherokee.. Getting motor at very reasonable price with low miles, hard to pass opportunity. <img src="/forums/images/graemlins/cheers.gif" alt="" />

welp, go for it!

None of the electronics on the 98 are compatable with the 91 ecu. The blocks and heads are will (pretty sure) but the 98 is an HO, and the 91 is not. There must be some differences not yet mentioned?

SD

It's been a while since I've seen the stickers on 91ish YJ's still on, but mine did have the HO sticker on there. I really couldn't tell you how high the high output was or why, I really never looked that up. So, Dawg, perhaps he has found a HO from 91....

? But figuring out these issues is the way that advance adapters made their millions, ya know.

Personally I'd rather not find out that I just bolted up an engine that does not work or work right.
Time is money.

SD