HO 99 Top End to HO 93 Bottom End

Can I simply swap the top end off my 99 XJ and onto my 93 MJ? Both have the 4.0l HO, but the valves and everything else on the MJ are getting tired, and I'd like to swap the whole top end from the 99 over.

Probably. See if they use the same intake/exhaust gasket so you know the ports will line up.

But why would you want too? If the top end of the 93 is tires, so is the lower end. What condition are: the pistons, rings, timing gears/chain, crank bearings, rod bearings, camshaft, lifters, oil pump, water pump, in? Chances are these just as tired as everything else.

Also you better measure the push rods from the 93 and 99, bet you find they are different lengths.

Norsk62 said:

Also you better measure the push rods from the 93 and 99, bet you find they are different lengths.

Click to expand...

Stock pushrods are oil-through type with pressed-in balls at each end. They are 5/16" in diameter and 9.625" long. I do believe they are the same throughout the production life of the 4.0.

But, suspenders and a belt... Won't hurt anything to double check the lengths.

I realize the whole motor is probably tired after 211k, but I blew up the bottom end on the 99 and the motor on the 93 is burning oil after idling (most likely valve seals or something similar). I'm not even sure if the head will be damaged on the 99 or not yet.