99 into 97 Engine Swap????

Would a 4.0L out of a 99 cherokee sport fit into a 97 cherokee sport with no modifications? If not, then what exactly do I have to do to make it work? I appreciate your response in advance, thank you!

Did you find out the answer to this question? I would also like to know.

My '97 XJ engine needs to be replaced, and I have a '99 XJ donor ready sitting next to it, and planning on moving the '99 engine and possibly tranny over to the '97.
What else needs to move over? I've never attempted an engine swap before, trying to get all the necessary info before I begin.

It isn't complicated. go for it.

Im 99% sure the 1999 tranny will swap over into your 97. As for the engine, i dont know.

I wonder if we could dig up a good link as to what year of jeep tranny's can swap into other years of jeeps. Im in the market for a tranny in my jeep also. I have 3 94 tranny's that close by on craigslist i could pick up, but i dont know if they can swap into my 98.

Yeah the tranny doesn't worry me, rather its the little things in regards to the engine, electronics, etc.

The '99 XJ engine is missing the throttle body, was hoping to use that newer intake manifold and I'm not sure if the throttle body from the '97 would be a bolt-in replacement.
Was reading a thread here on Naxja yesterday where a guy said there is a difference between 97 and 99 engines, some sensors of some sort, the 97 using 1 sensor whereas the 99 using two sensors, can't remember what it was for (eg. temperature, speed, etc) but something along those lines.

I hope if that's true that its the only thing I ought to be worrying about.


Anyone have any tips on what should be replaced on the engine while its out in the open?
I'm thinking rear main seal, oil pan gasket, and oil pump. What else should I be inspecting before I reinstall the engine? Also considering I've personally never seen/heard this '99 engine up and running before (previous owner drove straight into a telephone pole and wrote it off).

Anyone have any tips on what should be replaced on the engine while its out in the open?
I'm thinking rear main seal, oil pan gasket, and oil pump. What else should I be inspecting before I reinstall the engine? Also considering I've personally never seen/heard this '99 engine up and running before (previous owner drove straight into a telephone pole and wrote it off).[/QUOTE]


Harmonic balancer if the rubber appears funky. BTW, the trannies will bolt to all the 4.0s. The issues may be whether they match the spline count of the transfer case and which type of speed sensor triggering/plugs they use.

The engine will fit and the tranny will mate with no problems. The problems are always with the stuff that attaches to the engine, but with 97 and 99 they are really close already.

The computer talks to the sensors and injectors, so those need to be what the computer is setup to use. Go to rockauto.com, open tabs for 97 and 99 and compare part numbers--if a sensor or injector is different then remove the donor part and install the old part into the donor engine.

97 and 99 have the same heads and same belt routing so things like power steering and exhaust are the same, no worries there. I don't know about the fuel system plumbing, so check the fuel rail hookup, the evap setup, etc.

That's it. Basically unplug the electrical connectors on your current engine, remove said engine, install donor engine, reconnect electrical components, drive off

FWIW I put a 03 Grand engine a 96 XJ. SO Im sure you can stuff a 99 into a 97.

Some of the sensors will be a bit different and have different connectors. Of the top of my head I know that the oil pressure sender is different. Shouldn't matter though as mechanically, everything from the '97 engine will swap over to the '99 with no issues.

TerraWombat said:

Some of the sensors will be a bit different and have different connectors. Of the top of my head I know that the oil pressure sender is different. Shouldn't matter though as mechanically, everything from the '97 engine will swap over to the '99 with no issues.

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This is pretty much what I have found. I have had an '88 4.0L, a '95, '00, an '03 9blocks in my '88 Comanche with a '95 head) and I have a '98 Cherokee (parts for the '88 Comanche). The '99 should have the newr intake manifold, but the head, block etc. should be the same. The electronics; distributor, coil, NSS etc. are different. So, I'd swap those over from yours. I didn't notice if yours was auto or MT. I think the MT flywheels are the same from 91-01. I don't know about the auto flex plates. All tranies bolt up to all 4.0L blocks.
Besides the rear seal, I'd probably do the front seal too. Depending on money and milage on the engine, I might also, do a oil pan seal, valve cover seal etc. Also, an new oil pump. Besides the front oil seal, that might be overkill, though.
Tom

Thank you everyone for the useful input! I really appreciate it!

After all this I'm hoping one day I'll feel confident enough to take the old weary and broken '97 engine and turn it into a stroker =D

Just a quick update to anyone who's interested:

Engine swap went rather smooth. One or two multi-socket connectors were different between the jeeps, so I had to snip off the '99 connectors and put on the '97 connectors to make them match up with the '97 wiring harnesses.

The biggest setback was the transmissions. The '99 AW4 uses a 4-pulse per revolution signal to the computer, to let it know when to shift gear. The '97 AW4 uses a single pulse per revolution. Basically as soon as I started moving it would shift from 1st, into 2nd, 3rd, 4th and then overdrive almost immediately, doing 10mph! The fix was to remove the tail cone off the '99 AW4 and replace it with the tail cone from the '97 AW4. Apparently this change happened in MY'98.