4 to 6 Engine swap question

I know there must be plenty of info out there on the subject just can't seem to locate what I need.

Swapping an 88 MJ 4.0l motor into an 89 MJ that has a 2.5l. Can I swap the entire 4.0l engine bay harness (firewall forward)to the 89 and plug it directly into the existing 2.5l dash harness? Or will the dash harness have to be swapped as well?

Seems like the firewall back would be the same but :dunno:

Any tech write-ups links would be appreciated.

Thanks

Yes You can swap Just the engnine bay harness as everything else will be the same....

Yes You can swap Just the engnine bay harness as everything else will be the same....

That's what I was hoping to hear. My life just got a little easier. :jump:

I believe that's true with the Renix systems, however, I'm pretty sure the HO systems have to have all the wiring swapped.

I believe that's true with the Renix systems, however, I'm pretty sure the HO systems have to have all the wiring swapped.

Cool, I'll be pulling the whole drive train and harness from the 88 long bed and putting it into the 89 short bed(4 cylinder truck). Then putting the 94 HO drive train and harness into the 88.

Man, I'm gonna have a busy winter.

I thought the computers were different, 2.5 to 4.0. or does that count as part of the "engine bay harness"?

The Computer is a Given But Yes the Computer would need to be changed as well...

I've said it before and I'll say it again, the best way to swap a 4.0l into a 4-banger or v6 MJ is not to.

Buy a 4.0 MJ, then sell or part out your 2.5. Swap all your good/aftermarket parts onto the new truck then your done. If your smart about it, you could actually make money doing it too. These trucks are too cheap to try and do a 4.0l motor swap, when you can buy one with one in it already! It's a complicated and potentially expensive swap to achieve what, building an MJ with a 4.0l inline six?!

I thought the computers were different, 2.5 to 4.0. or does that count as part of the "engine bay harness"?

Yep, computer would go with the harness.

I've said it before and I'll say it again, the best way to swap a 4.0l into a 4-banger or v6 MJ is not to.

 

Buy a 4.0 MJ, then sell or part out your 2.5. Swap all your good/aftermarket parts onto the new truck then your done. If your smart about it, you could actually make money doing it too. These trucks are too cheap to try and do a 4.0l motor swap, when you can buy one with one in it already! It's a complicated and potentially expensive swap to achieve what, building an MJ with a 4.0l inline six?!

Reasonable sounding advice, that's why I asked the question.

A few things to consider. I've had a hard time finding a cheap, short bed in good condition, I already have the spare 4.0 drivetrain, the 4 banger truck is supposed to be in really good shape, just dirty(find out tomorrow), if I swap the entire motor, tranny and engine harness I was hoping the swap would be straight forward.

Specifically what undue complications should I expect?

Thanks

I've said it before and I'll say it again, the best way to swap a 4.0l into a 4-banger or v6 MJ is not to.

 

Buy a 4.0 MJ, then sell or part out your 2.5. Swap all your good/aftermarket parts onto the new truck then your done. If your smart about it, you could actually make money doing it too. These trucks are too cheap to try and do a 4.0l motor swap, when you can buy one with one in it already! It's a complicated and potentially expensive swap to achieve what, building an MJ with a 4.0l inline six?!

This is completely True statement If your Paying someone to do the swap if your doing the labour then this statement is false...

If You had a YJ or a TJ I would agree it is not worth the swap but When your talking an XJ or MJ There is nothing Hard or expensive about it since everything unbolts and is a simple Bolt in especially when you have a donor vehicle...

I've said it before and I'll say it again, the best way to swap a 4.0l into a 4-banger or v6 MJ is not to.

 

Buy a 4.0 MJ, then sell or part out your 2.5. Swap all your good/aftermarket parts onto the new truck then your done. If your smart about it, you could actually make money doing it too. These trucks are too cheap to try and do a 4.0l motor swap, when you can buy one with one in it already! It's a complicated and potentially expensive swap to achieve what, building an MJ with a 4.0l inline six?!

This is completely True statement If your Paying someone to do the swap if your doing the labour then this statement is false...

I don't have that luxury, it will be all me and a buddy or two.

Reasonable sounding advice, that's why I asked the question.

A few things to consider. I've had a hard time finding a cheap, short bed in good condition, I already have the spare 4.0 drivetrain, the 4 banger truck is supposed to be in really good shape, just dirty(find out tomorrow), if I swap the entire motor, tranny and engine harness I was hoping the swap would be straight forward.

Specifically what undue complications should I expect?

 

Thanks

off the top of my head, you'll need the 4.0 motor mounts, exhaust, and radiator related stuff.

I am doing the same thing in a 88 MJ. I picked up a 89 XJ with a inspection panel in the block for real cheap. I already had the engine. this way I am also getting rid of the basic gages cluster, and I am also going from a 5 speed to a auto tyranny. So swapping of everything will be in order

off the top of my head, you'll need the 4.0 motor mounts, exhaust, and radiator related stuff.

I'll swap the motor mounts from the 94 donor or fab some, exhaust and coolant system will come from the 88 LWB.

Got it! Picked up the 89 SWB, 4 banger today. It's in really good condition in and out(except being incredibly assnasty and a motor that sounds like it's about to come to peices). Best part is the sweet Buick steering wheel. :banana:

Now the planning and work begins.

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