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Old July 5th, 2010, 22:05
stockli stockli is offline
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Join Date: Jan 2010
Location: Ft. Collins
Posts: 452
Renix block to HO block swap: What I did and what works

OK the purpose of this thread is to answer questions people might have about swapping short blocks between a RENIX motor and an HO. I will list answer some of the more common questions in this initial post and try to answer any questions you guys may have.

First a little background on me. I am not a mechanic. I just like to tinker. Before this swap the most experience I had was tearing down and rebuilding my 1974 Norton Commando 850. A far cry from a modern multiport injected truck motor. There were points in this project where me and my bud felt we were in WAY over our heads (we probably were!) but with the help of the nice guys on here we were able to swap and even Frankenstein this Jeep back together into proper working order.

Moral of this story: Take your time and investigate using this forum and some others and you can do it! Follow the advice from the forum some of these guys really know there stuff and can help you solve your issues, or at least get you on the right path.

So here we go.

1989 Jeep Cherokee Limited. This truck was poorly maintained and generally a pile of shit. It has a solid body and a nice interior. When bought it was a hard starting motor that would idle poorly and die as soon as it was put in gear. We tuned the jeep up and went through the injection and electronics and came up with nothing. We replaced some electronics (TPS, CPS, IAC, wires, cap, plugs etc,they were at least 15 years old) A friend of mine (Certified Master Mechanic and electronics teacher, was called out to help diagnose the problem. After starting the car he became concerned at the obviously rough idle and wanted to pressure the motor to see what would happen.

The jeep started right up and was running terribly. Upon putting pressure on the motor it seemed to smooth out for an instant, then Bang! It seized right up, no warning. After removing and inspecting the dead carcass we found the PO had been driving the car with a bad oil pump. The 5 cylinder was warped and the crankshaft was pretty much welded to the connecting rod. I couldnt break the motor free with a BFSH and a block of wood. It was completely dead and frozen.

So there is the background.

If any of you are even thinking about pulling the motor, make sure you get to the back of the head and pull the top two bolts off the bell housing, FIRST!!! Trust me! There are plenty of threads on how to get at them, just trust me pull them first and save yourself a HUGE nightmare~

OK, so things you need to keep from your old block. Complete head, intake manifold, exhaust manifold, all RENIX electronics, flex plate, PS bracket, AC bracket, Alt bracket, distributor adapter, distributor, spark plugs, fuel rail and all parts of fuel/air system.

Most of the parts will easily directly swap right over. If you do this this will be an easy job. I do have a few suggestions and subs that work just fine.

Hake sure you pull your CPS before you pull the old engine out. You WILL screw yours up if you do not. They are not cheap either.

The big one is to use an HO thermostat housing. You will take your RENIX block temp sensor and thread it into the HO housing. This is the easiest way. I have not seen any downfall to this while driving the truck.

Be extremely careful not to crush any wires etc while swapping engines. Make absolute sure you have the distributor indexed properly! We used a rubber house fitted into cylinder one to find compression at TDC. This procedure is easy as pie if you take your time and do it right. If you dont it will be frustrating and you will get angry!

These are the major things I can think of right now I will add more as I think of them, and will answer any questions you guys may have as best I can.

You CAN do this. It is an easy and straight forward swap if you keep your RENIX stuff. Forget about a Cam issue you may have read about, the RENIX ECU does not mind the HO cam~

Good Luck, and dont be afraid to frankenstein smartly. Afterall this is a jeep we are talking about here.
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