FXWorks Posted September 22, 2009 Share Posted September 22, 2009 I have a 1988 RENIX 4.0 MJ with a blown engine. I have a well used but solid 1992 (ChryCo) EFI 4.0 from a Cherokee on an engine stand. What "non-obvious" stuff do I need to do to make the ChryCo 4.0 work in the MJ? Is it just swap manifolds or do I need to get a decent RENIX head as well. Other gotchas? In case it matters, the MJ is a 5 speed but I want to swap in a AW4 at a later date. Thanks! Link to comment Share on other sites More sharing options...
Pete M Posted September 23, 2009 Share Posted September 23, 2009 what part of the old engine blew? Link to comment Share on other sites More sharing options...
FXWorks Posted September 23, 2009 Author Share Posted September 23, 2009 Don't know at this point. I got the Jeep on the weekend. Previous owner said the engine was run very hot, the wiring harness sheath behind the valve cover is melted with the imprint of the valve cover fins in it so it was pretty hot. No coolant, oil in the sump is milky. The engine starts right up and there is no bad noises but it goes straight to WOT once you touch the throttle because the return spring is gone. I figured it would be easier to put in a "new" engine than mess with an unknown quantity. Link to comment Share on other sites More sharing options...
Pete M Posted September 23, 2009 Share Posted September 23, 2009 those 4.0s are insanely tough. I've had the 88's temp gauge buried in the red on 3 separate occasions with seemingly no ill effects. :dunno: what it takes to do what you want depends on how much you'd like to swap. the block interchanges fairly easy. the head brings on a bit more complexity. swapping the intake even more, etc. My searching skills aren't bringing up the threads I'm looking for :hmm: , so hopefully someone else can jump in here. Link to comment Share on other sites More sharing options...
FXWorks Posted September 23, 2009 Author Share Posted September 23, 2009 Well, maybe I'll just change the fluids first and see what happens. Link to comment Share on other sites More sharing options...
Pete M Posted September 24, 2009 Share Posted September 24, 2009 couldn't hurt. :thumbsup: Link to comment Share on other sites More sharing options...
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