Replace 1999 4.0 with 1998 4.0 -
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Go Back > Models > Jeep Wrangler Forums > TJ Wrangler Technical Forum > Replace 1999 4.0 with 1998 4.0

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Unread 07-27-2010, 10:06 PM   #1
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1999 TJ Wrangler 
Join Date: Jun 2010
Location: Utah
Posts: 69
Replace 1999 4.0 with 1998 4.0

I'm looking at very low mileage 1998 TJ 4.0 engine out of TJ to replace my very tired 1999 TJ engine. Not much available on the upgrades to the 1999 engine. A slight mod to the engine controller and added engine sensors is about all I've found. By checking some parts on the online parts stores I see that the head gaskets are different and the block part numbers are different. Motor Trend states that the 1998 had a 81mm stroke and the 99 has 86.7mm stroke yet the bore, displacement, hp and torque are all the same. I'm assuming that the head has been changed to maintain these specs. I suppose the HP and torque curves are flatter for a 99 but I'm not concerned enough with that to influence my decision, I just need to keep my Jeep on the trails for at least the next few years.
What I need to know is if I get a complete engine, harness, computer and all components for the right price ($600 tops) is there any reason to not do this switch?

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engine , swap , 4.0 , harness , wiring , advice , suggestion
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