98 TJ Engine Transplant

[The_DR]

I have a 98 TJ with a 2.5 Ltr engine that I'm replacing.

I got a rebuilt long-block from JEEP ENGINES & MOTORS | Rebuilt Engines that has arrived and I'm about to get started. I thought I'd document the whole procedure and post pics and stuff here.

Also I have good help available but I'm probably in a bit over my head on this project so I'm sure I'll be relying on some input and feedback from all you helpful folks out there

If anyone who's done this has any specific things I should keep in mind or "gotchas" I should watch for I'm listening.

Otherwise I'll update as the project moves forward and post questions regarding any issues I run into.

Thanks!

 

[Bounty__Hunter]

Best of luck, keep us updated and we'll help where we can.

 

[54cj3b]

I'm assuming your putting another 2.5 in. if you swap over all the hardware from your old eng to new before you install it will save you hours of time and make your life much easier in the long run and you wont need to struggle with tight spots that you cant quite get that wrench , also by doing this you know your putting things on new eng the correct way so you wont have any later on head scratching wondering where does this go ,
good luck and hope it all goes smooth for you

 

[The_DR]

So everything is going pretty smoothly. I have an engine stand that the new engine is on to swap parts to and an engine picker that's, well... let's just say "overkill" that I can leave the old engine on while I strip the parts off it.

I've taken many many pictures of the existing wiring and hose connections for reference as well as labeled most everything with masking tape, just to be safe.

I'm down to the motor mounts and transmission and it's ready to come out.

It seems like it would be easier to un-couple the transmission from the engine at the bell housing and leave the transmission mounted in place, but I've seen some conflicting opinions doing some research online.

Seems like pulling the transmission out with the engine means more work getting it out, more work putting it back in, and more trouble on the engine stand... Is there some benefit to doing it this way that I'm unaware of?

Anyone have any opinions on this?

 

[Bounty__Hunter]

I'd leave the transmission in the Jeep.

 

[drivers]

i am also planing to do a trans plant on my 98 tj from a 2.5 L up to the 4L
im having a little troble aquiring the new motor because its a friend of a family members and they just wont give me a price
i also like any input on this and look forward to hear af your sucsess with the install

 

[Bounty__Hunter]

i am also planing to do a trans plant on my 98 tj from a 2.5 L up to the 4L
im having a little troble aquiring the new motor because its a friend of a family members and they just wont give me a price
i also like any input on this and look forward to hear af your sucsess with the install

Good luck, you'll have to cut the motor mount perches from the frame and fabricate new ones. Upgrading to the 4.0L is a lot of work, often as much or more work and cost than a v8 upgrade.

 

[Utah_jeepster]

This question comes up regularly in JP magazine and other off-road publications. The cost of doing a 2.5 to 4.0 upgrade isn't worth the HP gains per dollar spent. Since you have to upgrade everything from the fuel pump to the ECM, wire harness, to exhaust your better off looking into a V8 transplant. Since a lot of the companies out there already manufacture wire harness conversion kits to bell housing and motor mount adapters.

 

[drivers]

so in other words i should either find a new project or just stick with my 2.5???

 

[Utah_jeepster]

so in other words i should either find a new project or just stick with my 2.5???

No I didn't say that, I am just saying the cost to make this change over without owning a donor 4.0L jeep with all the parts is considerably higher than doing a V8 conversion. There are numerous companies out there that have assembled kits to do a V8 conversion even 5.8 hemi kits and the 6.7 hemi that have all the parts, have done the conversions, and have taken the headaches out of the equation. But being a follower isn't what most jeepers are and doing it are own way is kind of what we are.

Since there isn't a large knowledge base out there of this type of conversion, your going to have to do a large part of research with different manufactures, Painless wire would be a good source for the ECM and engine bay wire conversion. As Bounty has pointed out you will need to fab in a new set of motor mounts...maybe someone at your local jeep dealer would know if there is a bolt in set? As to everything else...your going to have to run into these problems and figure it out. We don't know because like I said there isn't a big knowledge base for this exact conversion. 4.0L is a strong motor and has a proven track record, I have often dreamed for throwing in a V8, but I always come back to why change out a strong work horse for an unknown.
If you decide to do this, take many of pictures and post a daily log so we can follow along, and ask tons of questions, we might not be able to answer them, but hopefully we can steer you in the right direction.