What years 4.0 will fit fairly smoothly into my 88?

[Garrett]

I have a chance to buy a 96 cherokee 4.0 with 5 speed for 1000$ or 91 4.0 for 750. My question is which is better far as close replacement? Not really into frankensteining something, any ideas are appreciated.

[Minuit]

Not my text:

 

17. HO engine into Renix

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 1999 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 03/28/13

 

Either engine will require modifications to work in your truck. 88 and '91+ are quite different engines, but the above procedure will basically make the 91 or 96 engine function exactly the same way as in the 88. Are you swapping from a 4 cylinder or are you replacing a 6 cylinder?

[Eagle]

Either one will require either changing your wiring harness, or giving up the "HO" configuration of the "new" engine and setting it up to run with your existing RENIX wiring. If you're up to the wiring swap with the engine, I would choose the '96 because that's the first year for OBD-2, allowing you to use a common OBD-2 scanner. The '91 requires either a proprietary scan tool, or reading the fault codes by flipping the ignition key and counting the number of times the light blinks.

[HOrnbrod]

Either one will require either changing your wiring harness, or giving up the "HO" configuration of the "new" engine and setting it up to run with your existing RENIX wiring. If you're up to the wiring swap with the engine, I would choose the '96 because that's the first year for OBD-2, allowing you to use a common OBD-2 scanner. The '91 requires either a proprietary scan tool, or reading the fault codes by flipping the ignition key and counting the number of times the light blinks.

 

You can read the codes directly off the 91-95 OBD1 diagnostic port by using a Chrysler adapter cable and a code reader that will interpret OBD1 codes. No more counting ignition key blinks needed. 

 

   http://comancheclub.com/topic/46667-actron-obd1-scanner/?hl=actron

[Garrett]

It currently has the 4.0 with 142k. I know it needs rear main because it pours oil. I popped off the valve cover and noticed 2 rockers had way too much play so likely cam needs replaced. The caked on oil along with other things has me thinking just replace it with a running engine rather than dragging it out. I'm fine with making the HO act as a renix because not interested in messing with wire harness. Next question is will transmission i have, will it bolt directly to either? The 96 cherokje thats for sale has everything included. 91 is just engine. Mine is the ba-10/5. How about the oil filter mounting too, mine sits on top unlike my yj. Are these other motors set up top also or can that be swapped over as well?

[Pete M]

I would replace the rms and keep going. :yes:   nothing unique or even scary to me about your particular Jeep engine.  :thumbsup:  if it has good compression and good oil pressure, then in my opinion it's probably good for another 140k.   . :MJ 1: .

[Minuit]

Yeah, if the engine is mechanically healthy, the leaks can be fixed if it bothers you. Any engine you get will leak. Just a matter of life for our engines. I'd rather replace a cam than a motor if the bottom end was in good shape.

[Garrett]

Ok thanks guys, i havnt owned it long and had it running only for a few to notice the leak. Once i do the rms ill do the compression check.

[Minuit]

Do the compression test first. You don't want to tear into the engine just to realize it doesn't have any compression.

[Eagle]

Do the compression test first. You don't want to tear into the engine just to realize it doesn't have any compression.

^^^ This

[Garrett]

Way better plan. Thanks again.