Wackpackxj

New to forum. Hoped to find more tech support pertaining directly to the XJ than previous forums explored.

I retired my second 96 4.0HO Xj in February to a local salvage yard with about 300k. Drove it there in fact. Still running tip top and driving, wheeling just fine.
Laundry list of problems kept me from continuing to drive it daily.
Rotted floors, 70% cut out in prep for new pans being #1 I couldn't drive it like that with children and winter/rain.

$500 towards my new found $1500 1999 gem on CL. And the comfort of knowing right where all my good parts were if I should need any.

My 99 is everything I've come to expect. Aside from my newest most hair raising predicament. Pretty positive the cylinder head is cracked.

I developed a misfire. Ok (intentions were tune up)
Not before it began over heating.
I drained and flushed, purged the core, removed the stat, inspected hoses, fan clutch, new pump, electric fan functioning, rad cap.
All good? No. I did not replace stat but reinstalled housing. Added cleaner and topped off with water.
It ran fine like this for a week. Began overheating again on my way to work. After work I topped off with water again, witnessed a bit of white smoke leave the tale pipe for five minutes. Engine was now overheating much quicker. And I DID see steam leaving the manifold side of the engine. But from under the manifolds so I really can't get a good look at the side of the head.
We did find some water had made it into my oil. But I had probably checked my oil days prior. I honestly open my hood every other day.
That being said I decided to go ahead anyway with my complete tune up.
Plugs, wires, cap, rotor, filters fine. And of course an oil change.
I purchased a miracle product called KW block and head sealer.
It seems to have lessoned the water consumption but has not 100% remedied the problem. After about 3 days of running idle in the driveway and carefully driving it no more than about 15 miles trips the sputter and rough idle remains.
And I have yet to drain and let the cooling dry out according to directions.
I do not want to fill with another $20 worth of coolant and replace the thermostat if the perm fix inevitably is replacing the head :/

I know for a fact that the Head is interchangeable.

NOW my question is.

Is my entire Engine,tranny,TC from the 96 going to swap right into the 99?

If so then that's the plan. So I can continue to drive it while completely rebuilding the 150k 99 that I yank out.

So sorry for the huge post. And thanks in advance for reading and sharing your thoughts. I just didn't wanna come off as a noob. And didn't wanna dance around with BS. Just right to the point.

Of all the common Xj issues this ones gotta be the worst.

salad

If your 96 really was running that well, go get the whole engine. Coolant in oil is bad news for all of the bearings. If you want to replace the head, at the bare minimum take the rest of the engine apart and inspect everything.

No need to swap the tranny and TC. Unless you drive manuals the 96 AW4 is not a direct swap with the 99.

Wackpackxj

Oh well I got my answer. So much easier to pull it all out without having to crack it open. Don't need two men for that.
As good as the 96 did run I'd be hard pressed not to rebuild that entire 300k engine.
The valve job and resurfacing would be cheaper and take less time. But you're absolutely right. I have lost a significant amount of trust in the integrity of my bottom end. But once again time and money play a huge part in my decision.
At LEAST I know that my 96 was well taken care of. Despite the mileage I wouldn't know anything for sure if I purchased a random salvage engine. Regardless of mileage.

Sadly it would seem I will be driving it daily armed to the teeth with bottles of water and a AAA card. When my luck runs out I will hopefully have already done a semi rebuild on the 96 4.0. As much as I like to get my hands dirty I lack the motivation to start this project.

Thanks for your input. I really shoulda just bought another 96. Cuckysucky****y