Long time lurker, finally got around to registering today...
I've been looking for an XJ for a long time. Finally found one not running on the cheap. I fully expected mechanical problems, but... sheesh....
The rust in the exhaust port was an ominous sign (aside from no compression on the first 4 cylinders), and the #2 piston was shocking. Cylinders 1, 3, and 4 were missing chunks of the pistons around the perimeters. Believe it or not, this thing was actually running (very poorly, though. It wasn't driveable)
Now it's decision time regarding engines....

 

Wow how does that even happen

 

wow i have never seen that before. that is insane. i would buy a new to you/used 4.0 and stroke it. lol thats everyones favorite is stroking. the engine......

 

I bet I couldn't have done that if I tried. I bought it like that. There was absolutely no water in the radiator. I don't know which one caused the other, but I knew there were major problems. I've had several hot rods and torn some stuff up, but I've never seen anything like that on an engine that would still crank up...

 

I am considering building a stroker, however that will probably be a leisurely long term project. Right now, I'm trying to decide between a junkyard engine for a hundred bucks and replacing oil pump/seals/gaskets, or a long block assembly for 1500 w/ a 3 year warranty. I'm still on the fence...

 

I'd go jy, and I have more than once, and save up for the monster build later on. I've seen where a hydrolocked motor will crack pistons and bend rods like that.

 

X2 on the jy. then spend your money on a bamf engine.

 

I think thats the direction I'm leaning. I'm going to go to the jy with a battery, remote start switch, and a compression tester and spend some time probing to see if I can find one worthwhile.

 

WOW that is insane I would really like to know how that one happened. As for the motor i would personally go with the junkyard.

 

Just remember you don't want anything older than a 91 cause it's a little bit different motor. You can make it work but it's a bit more work. I just swapped a 96 model into a 93 about a month ago, aside from having to swap some sensors it was about the easiest motor swap I've done except for the sbc in muscle cars in my younger days.

 

stroke it...

 

Well I found a 98 Grand Cherokee with a 4.0 at the local jy. I generally have a rule against taking a jy engine from a vehicle that isn't wrecked, but there aren't a bunch of options there. There are a couple '94 cherokees, but according to their odometers, they have 331K and 316K miles on them. The grand had the transmission and starter stripped, so I couldn't check its compression. I may go back and get it tomorrow. Hopefully it's at least rebuildable if it won't run. It can't be any worse than what I have now.

 

Sometimes, but what does that have to do with an engine?

 

WOW, that's impressive.
I didn't know it was possible to mess up a 4.0 that badly!
+1 on the j/y motor with a gasket & seal replacement.
MAYBE there's a few usable parts to use in a stroker. Maybe.

Best of luck with the j/y motor...hope it's a good one.

 

Yep. That's pretty bad.