I have searched and searched for information on this and have gotten conflicting information! I have 98XJ with ~163K miles. I get a misfire on cylinder one code and compression test only gives me 83PSI! Other cylinders are OK, but this motor is tired, as several others are low too. I have access to a 2000 XJ motor that is very low miles for a good price. I just want to drop it in and keep driving as it is my daily driver.

I even went as far as speaking with several jeep techs at more than one stealership. The consensus from them is that the engine will work just fine if I drop my distributor in and get rid of the spark rail. However, I have seen others say that this won't work because there is no way to mount the coil?!

If the only hold up is mounting the coil, this seems extraordinarily minor compared to swapping engines as I should be able to just fab a mount for the coil correct? I am also aware that there are differences in some of the brackets on the front of the engine but I plan to get those with the engine.

I would great appreciate any advice as I have already promised the cash and need to get this resolved...and before you say it, no I am not able to pull this motor and stroke it at this time. That will have to be a few years done the road. I just have to swap and go over a weekend because I have to have it back on the road fast.

Thanks in advance,
Mark

 

Those guys at the dealership have a job there for a reason. They know what they are talking about. Fab up a coil mount, drop in the distributor from your 98 motor and have anice day with your new low miles 00 motor. Be sure and use the original ECM that is in your 98 XJ, also.

 

Hey, thanks for the reply. I certainly hope so, but I also have had encounters with ASE certified techs that I wouldn't let change my "blinker fluid"!

I was planning keeping pretty much everything that's in the '98 except the newengine, and new intake manifold. Supposedly this intake with the longer runners provides more power, but I have also heard that is only if you use the older heads but have also heard conflicting information about what year heads! I won't be using the head from the '98 right now because it would need to be re-worked and I can't afford to have the jeep off the road that long.

If everything works out right I should have an XJ running good with a low mileage motor and a second complete 4.0 to be stroked at a later date! I've always wanted another CJ with a 4.0

Anyone else want to chime in? I'd appreciate it!

Thanks,
Mark

 

I have always heard before that the the head casting (7120 = 91-95) was the best flowing 4.0 head ever built. I recently read that the (0630 = 96-99) flows better. All I know from personal experience is that with a better air intake and exhaust put on my 91 4.0 HO head flows pretty darn good.

 

I have had the OBD report a couple misfires. Should I be concerned about the same thing?

How can I get the compression of the engine tested?

 

Pull your spark plugs and get a pressure gauge and check the compression yourself.

 

I wouldn't worry about compression being the first problem. If it is restricted to a single cylinder, for instance mine was always cylinder #1 there are a couple of things you can try. One is that you could have a bad injector. To test this depressurize your fuel rail and move the injector from the suspect cylinder to another cylinder and see if the code follows the injector. If it does then the injector is the problem. You can do the same thing for plugs and wires. If nothing makes the misfire move to a different cylinder then it is more likely something in that cylinder or its valves.

A compression test is very simple, your generic manual should explain how to do it or there is always Google, Im sure that you can rent a compression tester at any parts store for next to nothing. If you have low compression on a cylinder try squirting a little oil in the plug hole. If it comes up a little it usually indicates rings as the oil helps seal the rings and bring the pressure up. No change means vavles/head.

If its just the head and you are adventurous you could always just pull the head and have machine shop run it. Personally though, I would go ahead and do the whole deal while you're in there, because you'll have to eventurally!

Good luck,
Mark

 

This agrees with what I've heard as well. The "pre-95" heads flow best and when combined with the '00 + heads give a significant HP boost. I've heard as much as 15 ponies.

Mark

 

Wanted to bump this back up and see if anyone else will chime in with know compatibility issues on this swap?! I'm picking up the motor soon so anyone, ....Bueller?

Thanks guys!