This June I bought a 2000 Cherokee with the 4.0 and a bad engine. Teardown revealed a busted #3 piston having about a area the size of a quarter broken off the top along with the skirt section. It also had a cracked cylinder head. Replaced the head with an 03 and rebuilt the lower end .060 over pistons. Runs excellent. Now I bought a 2000 Dakota with the 2.5 Jeep engine and it ALSO has a bad piston EXCEPT this piston completely disentigrated into hundreds of pieces. The head is coming off today and I will see if this one is rebuildable. Seems that pistons along with cracked heads are pretty common in these engines. Why are the 2.5 engines SO HARD to find? And so expensive? They must have built 100 4.0 engines for every 2.5 after 1997. Can't find anything out there because I am pretty sure this block will not be rebuildable.

 

the 2.5 blows! It has no power and drinks almost as much as the 4.0.

 

Piston skirts frequently crack in the 4.0L engines because most think that they can just hone and re-ring the engine to do things on the cheap rather than replacing and boring the cylinders like they should. Glad to see that you didn't fall into the "norm for this forum" and actually did right by your jeep by boring the cylinders and replacing pistons. Although .060 is probably overkill.

 

Tore down the engine to bare block and looks like I got lucky because the head only requires two new valves, all new stem seals and valve seat finishing. Block has very minimal scratches along #3 cylinder walls that a .030" overbore will fix. Man that cast iron made mincemeat out of that poor aluminum piston. It was literally in hundreds of pieces with the largest piece being about the size of a half-dollar. I might consider overboring to .060" just to try to get a couple more horsepower out of the poor little engine. Anybody have any other ideas to help power up this 2.5? Engine swap is out of the question so if it doesn't involve upgrading this engine please don't comment. Maybe regrind the camshaft to a little more lift/duration? Anybody? Thanks

 

More power from a 2.5? Push it off a cliff.

 

The 2.5 in the dakota was the base engine indended for general purpose use, not performance. It will do better with a manual transmission than the automatic. If you want performance, get a dakota with the big V8!

A friend has a dakota with 2.5 & manual for parts (engine runs good) if you need one.

Thx-Ace

 

What year is your buddy's Dakota? The early models used the same 2.5 as the K car until I think about 1996, then they changed over to the Jeep 2.5.

 

I don't know the year but I can find out for you if you like. He is a chrysler/dodge/jeep mechanic and knows his stuff. He said it was the jeep motor and offered it to me but I don't need it. The truck is ragged out bad but the engine sounded fine. Thx-Ace