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4.0 and 4.0 ho compatibility questions

652 views 1 reply 2 participants last post by  Marty, SoCal 
#1 ·
I have an 89 xj with the 4.0 and auto trany.

The engine is toast.

Will a high output engine have any problems going into the 89 xj?

Here are some things i'm worried about:

- Engine to transmission, will they fit fine?

- Computer, will the renix system be able to handle the newer motor and would I need to switch harness connectors?

- Will the fuel line to fuel rail interchange

- Are the power steering pumps the same
 
#2 · (Edited)
If you treat the HO motor as a long block, basically reusing all the earlier Renix parts it will bolt in. Be sure to reuse the 89 flywheel, intake and exhaust manifolds, etc. Should run OK, too.

One problem may be the pilot bearing, if the HO is newer than 1992, the bore in the back of the crank is not finish machined to fit the early pilot bearing properly, the stock, or bronze pilot bearing/bushing will need the OD turned down to match the bore in the back of the late HO crank. If you have an AW-4 automatic trans, it fits fine, no mods to fit the converter are needed.

Stay away from the later "WJ" style blocks, the ones with the coil on plug ignition, as the block bracket holes are different and the stock XJ mounts won't fit.
 
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