My buddies wife's 99 WJ 4.0 died and I have my old wrecked 98 XJ with a good 4.0 in it that we would like to swap into the WJ. What I basically need to know is if this is a doable swap? I know that the 98 4.0 has a distributor ignition system and the 99 WJ has coil packs instead. Is this just a simple matter of taking out the distributor and putting the plug in its place from the 99 bad engine and swapping everything over onto the 98 block and swapping it in? I am assuming that the motor mounts are the same and if they aren't I can swap over the WJ's mounts onto the XJ's block? Any insight you guys could give me on if this swap is possible and what all is involved would be much appreciated.

 

After reading various posts here and on the internet I am getting conflicting information. Some say it is a simple matter of just swapping everything from the new block over to the old one and others say it wont work. Has anyone here actually done this swap before and could chime in with some advice?

 

I know this is a year and a half later, but I'm currently trying to figure out if I can stick a 98 XJ 4.0 into a 2002 WJ.

PeeDeeJeep did you ever sort this out?

Thanks.

 

No I never did. I am guessing no one here knew the answer.

 

XJ Cherokee and ZJ Grand Cherokee 4.0L engine blocks interchange.

2000+ TJ Wrangler and WJ Grand Cherokee 4.0L engine blocks interchange.

XJ/ZJ blocks and 2000+ TJ/WJ blocks do not interchange without significant modifications. (1997-1999 4.0L TJ Wrangler blocks will interchange in XJ/ZJ and visa-versa).

TJ/WJ 4.0L Engine blocks underwent clean sheet design changes effective in the 1999 WJ Grand and 2000 TJ Wrangler. These blocks are not interchangeable with XJ/ZJ engine blocks. The reason is motor mount bolt holes and belt driven accessory mounting bolt holes are in different locations, or not present at all, TJ/WJ vs. XJ/ZJ.

 

^^This..


You can see the added bosses and tapped holes in pic and compare to an XJ/ZJ/YJ engine and see the difference.

For added tech: Brown Dog makes a conversion bracket to use a WJ engine to an XJ, but not the opposite.

I bought a clean one owner WJ with a broken piston thinking i could use a 60K mile XJ engine i had on engine stand.. i couldnt.

 

Thanks guys, I've been searching for days, and just like PeeDeeJeep, I was finding very conflicting information. I guess it's all about asking the right question, at the right place.

I guess on the plus side, it got me to make a Cherokee Forum account, which I've been meaning to do for some time now.

Thanks again guys.

 

Welcome. CF is my most favorite Jeep forum.

 

Thanks! I have (currently) 3 XJ's, and now a WJ, but I've had 3 other XJ's, and a YJ. I scan CF for answer a lot, but never had a really good reason to sign up.

 

I just wish I would have gotten great detailed responses like this when I originally made the post. It would have saved me allot of time and headache. I pretty much stopped posting here because I never got any responses.

 

So, just to add to the "future reference" database for anybody looking for this answer, here is a picture of what I assume to be a '99 block. Even after all this info, and pictures, I still screwed up and bought an engine that was supposed to be out of a 2003. Here it is. You can see the boss difference between mine and the one OverlandZJ posted. This one also does not have the lower boss on the other side for the AC pump.

FWIW, the head on this one says "99" and "WJ", and is a 0331, but it is not a TUPY head.

Just sharing my ongoing mistakes so that others may not have to make them.

*EDIT* I feel dumb. Finally got some cross references for the numbers on this block. It's an XJ block (which is why it wouldn't fit). All the same, it stands as a good reference picture for this thread.

 

"2000+ TJ Wrangler and WJ Grand Cherokee 4.0L engine blocks interchange.

XJ/ZJ blocks and 2000+ TJ/WJ blocks do not interchange without significant modifications. (1997-1999 4.0L TJ Wrangler blocks will interchange in XJ/ZJ and visa-versa)."

Ok, I get that an XJ/ZJ block will not fit into A2000+wj, BUT WHAT ABOUT THE 1999?

This issue is plaguing me!!!!

 

99 what?

If your asking about a WJ.. it's the same as any other WJ clean slate block.

 

I see what you're confused about. Read it like this: "XJ/ZJ blocks and 2000+ TJ/ (Any) WJ blocks do not interchange without significant modifications."

The 2000+ was in reference to the TJ alone, not the TJ/WJ combination. I think I had this issue at one point also.

Like Overland said, if it's a WJ, it's the new design (98% sure I didn't just lie to you).

 

thank you for clearing that up. OI was so confused. My engine will not fit into my jeep... Makes me sad...