exhaust manifold question on 4.0 89 comanche

[pitbull4x4]

I have a 89 Comanche with a 4.0. Bad motor so swapping in a 96 XJ 4.0. Can I use a exhaust manifold off a 96 XJ or do I need to stay with a 89 exhaust manifold. I'm using the 89 intake

[onlyinajeep726]

You can use the HO style ('91+) exhaust manifold or aftermarket headers, but you'll have to obtain the HO down pipe to make it work, or bring it to an muffler shop to have a custom one made.  I just went to the junk yard and pulled said down pipe from a ZJ (as those don't have a crushed end to clear the front drive shaft like the XJ and MJ ones).  It would be a good idea to grab the transmission rubber mount from the cross member of an HO era XJ or MJ too, so that the new down pipe will slide into the vibration dampner that's built into that mount.

[teamsmith]

I am just wrapping up same project. I used 89 intake, ho exhaust and I bought an ho down pipe for $44 off Amazon. It lined up perfectly with the header and the tail pipe. It also mated to the bracket that goes into the vibration isolator. I plugged the egr pipe hole on the intake with a bmw oil plug. I bought a couple extra if you need one. The oxygen sensor will screw into down pipe instead of the headers but the wire will still reach.

 

 

Let me know if you have any more questions; I've learned about every way that you can do it wrong. Actually, my truck, which is still down until I figure out the clutch, is not far from you. Just across the river in Dayton, TN. 

[pitbull4x4]

Thanks for helping this old guy out !!!!

[cruiser54]

Here ya go. The whole shebang, soup to nuts.....

 

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 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