jhall

I threw a rod in my 99, can I swap out my engine in the 99 with an engine from a 90?

salad

If you're swapping just the block, yes. If you're bringing the head too there are some things to take care of.

jhall

I got a pretty sweet deal on a 90 that this guy cant afford to fix up. Evrything on my engine is in good shape I was jusr planning on. Swapping the block and putting all of my current parts on the 90 block. So my plan will work?

tiegs89xj

After 1990 Chrysler bought the jeep corp. the changed the spline count from 21 to 23 so if you swapped in the 90 ending you would need new tranny, t case set up

jhall

Can I just swap the t case from the 90 to the 99. Sorry for all of the questions I just am not that knowledgeable about all of this stuff but would like to be.

cruiser54

We're talking engines here. The spline count was trans to transfer case.

And, Chrysler bought Jeep in 1987. Took a few years to implement changes due to contracts with Jeep's suppliers.

cruiser54

Here's how to go from Renix to HO. Use this as a guide to swap the other way. You'll be fine. Be sure to use an intake/exhaust gasket that matches your manifold, not the head.

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 07/24/2012

　

jhall

Cruiser, my mind is blown. Thank you so much for the help. I wound up at the last minute finding another 90 that was in great condition. I bought it instead and she's running like a boss. I'm beyond impressed with tbe knowledge on here. Thank you.