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Ianbeaulieu 07-17-2013 02:15 AM

4.0 from a TJ
Hey, my friend has a 97 TJ and just rebuilt the motor, he is going to put a 350 in his TJ and said I could have the 4.0 in it, what all would I need to do this swap? And should I do it? I currently have the 4.2L

dukes-o-hazard 07-17-2013 04:36 AM

Seem's easy enough from what I read 90 4.2 to 95xj 4.0 Swap Build Thread -

90DesertTanYJ 07-17-2013 06:47 AM

Not speaking from experience but I would think it would be pretty straight forward. The only thing that might be different would be electronics. Chrysler went to their own engines when retooling worn out molds for the 4.0 was more expensive than converting to an existing engine in their line up.

JoeyT 07-17-2013 03:38 PM

I just put a 4.0 in my 4.2 YJ. It is not that easy. I ended up using the entire harness from the donor vehicle. At the very least you will need his harness from the firewall forward ( he can use yours to hack up to make his jeep run )

That being is a mess. In order to get the CEL and other warning lights correct, it is much easier to use his complete interior harness. You will also need his fuel tank, or you will need to install an aftermarket fuel pump.

In short.... if your 4.2 runs, take his 4.0, put it on a stand, and buy a 4.0 YJ with a blown engine and a rusted frame. Then do the swap.

Ianbeaulieu 07-17-2013 06:05 PM

Well he is going to give me everything I need, like the harness and stuff, I would figure I can just plug back in the gauges and they would work

JoeyT 07-25-2013 08:18 AM

Doesn't work that way. I doubt the car side TJ harness matches your dash, and your existing car side harness won't work with the engine side TJ harness.

Make sure you can find a YJ car side harness before you start.

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