Motor Swap?

[bumpy]

I'm sure theres a million topics on this, I'm too lazy to read them all so hopefully some of yas can give me constructive criticism instead of destructive...

 

i got an 1987 Jeep MJ from here with the renix 4.0... motor blew up about a month or so after acquiring it.. its in really good shape for the year and i wanna make it run again as i miss my Jeeps!! so basically I'm wondering if i can swap in upto a 99 motor and ECM or is it a PITA to do?? should i look for the pre 91 motor or the 92-99 motor? should i swap on the 99+ intake manifold for better flow? should i put a header onto it? what all would you do if you were about to swap motors??

 

i hate electronics but can deal with everything else, i will have a friend helping me who loves car electronics so it shouldnt be all too hard... i have swapped 4 Jeep 4.0s in my past, a 92, 94, 99 and 2000... so I'm assuming itll be alot like the '92, fairly simple but will have the renix cooling system right??

 

basically my questions are what all do i need to look for in swapping the motors? ideally id like to swap in a 92-96 motor and add on a header and the later intake manifold for better power and all that BS... what would you do if you had the chance?

 

The MJ is a DD, pulls trailers and plows snow, so reliability is a must! its one of the work trucks for my landscape company and will be pulling a 6x12 trailer this year... lucky for me it has the D44 and trailer brakes already installed!

 

Thanks for any and all help and advice fellas!!!

[ftpiercecracker1]

Small block 350 with a 700cfm holley carb  :D , if you don't want to fool with electronics or have a/c. If you just want the simplest drop and go i think you already know another 4.0 is the way to go. Any 4.0 will work, some just require a little modification in other ares. For simplicity sake don't mess with your current electronics, when its running right Renix is pretty darn good management system and if you go changing the engine harness you will have to change the dash harness, which also means changing the dash itself.

 

Cooling system is completely up to you, either closed or open can be done fairly easily, regardless of year.

 

FYI 

 

I just finished putting a junkyard 93 ZJ 4.0 into my 89 MJ, runs great! Still using the Renix and the closed cooling systems. The only problem i had was the pilot bearing, the one for the ZJ had the wrong ID for the transmission snout and the one for my MJ had the wrong OD to fit in the ZJ block. Other than that it was strictly a bolt on afair. :thumbsup:

[onlyinajeep726]

You can swap in any 4.0L from '87 - '98, however, I would advise a '91-'95 for the better flowing heads and to ensure that the casting for the blocks have all the needed sensor ports drilled and tapped.  Knock sensor comes to mind.  Not saying that anything past '95 won't work, but I'm fairly certain that at least up to that point, it was at least drilled (and most tapped).  I also know that once you get past '98, due to the coil pack design, there isn't a spot to place a distributor.  My reasoning for '91-'95 is those are HO's and still use a fuel pressure regulator on the rail with return line so you can still use your current fuel pump.  There's a lot more stuff to consider, but that's my main point.

[ftpiercecracker1]

I also know that once you get past '98, due to the coil pack design, there isn't a spot to place a distributor. 

 

 

can't believe i didnt think of that.   :doh:

[HOrnbrod]

You can swap in any 4.0L from '87 - '98, however, I would advise a '91-'95 for the better flowing heads and to ensure that the casting for the blocks have all the needed sensor ports drilled and tapped.  Knock sensor comes to mind.  Not saying that anything past '95 won't work, but I'm fairly certain that at least up to that point, it was at least drilled (and most tapped).  I also know that once you get past '98, due to the coil pack design, there isn't a spot to place a distributor.  My reasoning for '91-'95 is those are HO's and still use a fuel pressure regulator on the rail with return line so you can still use your current fuel pump.  There's a lot more stuff to consider, but that's my main point.

 

And a good point it is.  :thumbsup:

[onlyinajeep726]

 

You can swap in any 4.0L from '87 - '98, however, I would advise a '91-'95 for the better flowing heads and to ensure that the casting for the blocks have all the needed sensor ports drilled and tapped.  Knock sensor comes to mind.  Not saying that anything past '95 won't work, but I'm fairly certain that at least up to that point, it was at least drilled (and most tapped).  I also know that once you get past '98, due to the coil pack design, there isn't a spot to place a distributor.  My reasoning for '91-'95 is those are HO's and still use a fuel pressure regulator on the rail with return line so you can still use your current fuel pump.  There's a lot more stuff to consider, but that's my main point.

 

And a good point it is.  :thumbsup:

 

Thank you! :rock on:

[cruiser54]

No wiring needed. Do this:

 

Cruiser’s HO into Renix Swap

This swap is easier than some will lead you to believe, generally those who have never done it. Those of us who have done it, like myself, will share with you the things that need to be done for a successful swap. Just think of it as swapping in a long block.

The HO and Renix have some differences but none that can’t be overcome very easily.

Any HO engine from an XJ or ZJ through 1998 can be used. One running change was that the rear of the head was no longer drilled and tapped for the temperature gauge sender beginning in the 96 model year. The sender can be relocated to the threaded hole in the thermostat housing taken from the HO engine. You’ll have to extend the wire to that location. Some brave souls even drill and tap the HO head for the sender.

You will be using the intake and exhaust manifolds from your Renix, along with all your sensors and wiring. Since the intake ports of the HO are slightly different, you use the Renix gasket. Exhaust ports are identical.
You will need to use your Renix distributor as it is different than the HO because they use different fuel management systems. The  flywheel or flexplate from the Renix must be used so your CPS gets the correct signals. The valve cover from the Renix allows you to keep your CCV system intact and requires no modifications.

The HO block will have a plug in the coolant galley on the driver’s side of the block, closest to the front, which needs to be removed so your Coolant Temp Sensor can be installed in it’s place just as it is on the Renix. It requires a 5/16” square drive or a modified 3/8” drive that has been ground down to fit. Do this before installing the engine.

As for the knock sensor, which is located just above the oil pan on the driver’s side of the engine about mid way, all the blocks I’ve seen are threaded for it. If not, I’ve heard they may be drilled but not tapped. Tap the hole if that’s the case.

Revised 07/24/2012

 

[ftpiercecracker1]

 . . . .Any HO engine from an XJ or ZJ through 1998 can be used. . . .

 

 

 

 

Forgive me master, but i must interject :bowdown: .

 

I recently, as in last week, put a 93 ZJ into my 89 MJ. Everything worked, EXCEPT the pilot bearing, neither the ZJ or MJ pilot bearing worked. ZJ had the wrong ID to work with the AX-15 snout and MJ bearing had the wrong OD to fit in the ZJ crank. I had to take the MJ bearing with the proper ID and grind the OD until it fit in the ZJ crank.

[cruiser54]

Good to know. Hopefully, the OP has an auto.

[bumpy]

its got a ba-10 or ax15, i havent looked at the numbers on it... I'm thinking ax15 as it didnt grind or anything shifting...

[cruiser54]

 

I also know that once you get past '98, due to the coil pack design, there isn't a spot to place a distributor. 

 

 

can't believe i didnt think of that.   :doh:

It's not true. Coil packs came out 2000 or later. and even then, you remove the dealie bob that's in the distributor hole in the dizzyless engine and drop your dizzy right in.