renix 88 engine replacement

[laxplayermjd]

Hey guys, much needed help here. I just purchased an 88 xj. I just pulled the motor because it was over heated. It has 185k miles. Upon inspected found some freeze plugs rotted through and coolant was entering right into the oil. Previous owner put 91+ exhaust manifold on.

I am planning on going to pull a part to get a complete motor for 100 bucks. This is temporary as will build the stroker once the jeep is on the road as it hasnt been daily driven since 2004. My questions are if they dont have an 88-90 for a direct swap. What exactly needs to be done to put 91-95 motor in.

Ive read the throttle bodies are diff, the intake and exhaust manifolds are different. Temp sensors are different locations. Does 91-95 blocks have hole for knock sensor? I need to swap flywheel. I wish to keep the renix system and keep the swap simple. Are the exhaust ports the same on the non ho vs ho head. But the intake are higher ports. But can u use renix intake just fine with this head? Or can u use ho intake with renix throttle body so theres no tps mod. Or do u have a simple diy for tps mod.

Any and all help appreciated. I would like as much details and pics as possible for help of swapping in a H.O. engine into renix vehicle keeping renix system

[5-90]

Drop in the short block. The only change made there (in terms of control setups) was the boss for the knock sensor went unmachined after 1991. OBD-II (1996-2007) /may/ not support the ECU coolant temperature sensor - but I haven't checked (you can probably see the boss for that as well, and drill and tap it.)

Keep your RENIX block - it can be machined into a stroker short block for later.

You will have no mechanical trouble dropping the RENIX top end onto the later short block, and stick to RENIX plugs and such for the head.

The temperature sensor for the gage won't be at issue - since you're keeping the RENIX head.
The KNOCK sensor can be deleted, or you can drill and tap the boss to accept the knock sensor on the HO short block (/do/ /not/ drill through! The knock sensor does not need to communicate with any fluids, it merely needs a solid mechanical connexion to the engine block. However, it only generates a signal when something is going wrong, so it can be - and sometimes has been - deleted temporarily.)
The coolant temperature sensor behind the exhaust manifold needs to be retained, since it is the one that reports to the ECU. Provision for that was, I think, maintained until 1995 - the boss would probably have remained in place afterwards. If it did, drill through and tap for the sensor, then flush the chips out of the core pocket before you install the block.
Just about all of the other sensors are found in the top end, which you will be retaining for simplicity.

[ARH]

Upon inspected found some freeze plugs rotted through and coolant was entering right into the oil.

Elaborate?

[Mgardiner1]

How does freeze out plugs cause antifreeze to mix with the oil? Freeze plugs are external to the engine block for antifreeze only. If you are getting coolant in the oil, then suspect cracked head/block/blown head gasket.

[laxplayermjd]

That was just the quick inspection. I know its not goin to be good. Being as i believe nothing but water was added to the cooling system since 2004. Havent had a chance to pull the head off yet. I just know after a couple days with fresh oil it was already gray coming out..Then i may just build the stroker. Gotta get an engine stand, cant use works for too long, when i do ill disasseble and see.