1988 cherokee engine question

[robslob]

i have a 88 Cherokee with a horrible rod knock so i have to replace the engine. i plan on going to the junk yard and pulling one from there. the thing is that all of the 4.0 look the same. what years have the same engine? anyone know of a good place to get engines?:

 

[MudderChuck]

I had a pretty good rod knock in my motor (89), replaced the connecting rod bearings and the oil pump. That was about a hundred thousand miles ago.
A actually had/have an extra motor in the garage and thought, what the heck, fix what I got first and see what happens. The extra motor is still sitting there.
A lot of times, these things are kind of mileage dependent and all the motors of a certain age have just about the same things wrong with them. Just in some it shows up a little later than others.

 

[hogseye]

It is my understanding that Jeep 4.0's did not change until 1994. After that you have to make other modifications. Don't quote me on that. I am with Mudderchuck on the rod bearings though. These engines have a lot of stroke and rod bearings are the weak link. Also the oil pumps are notorious to go bad also. Have just finished installing a set of rod bearings and a new oil pump in my 87 4.0. The mains were fine and the crank was not rough either. If the engine runs ok otherwise it might be worth your while to look into that. A junkyard engine is always a crapshoot also.