3 freeze plugs not 5 in new block - JeepForum.com

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post #1 of 4 Old 03-17-2013, 06:12 PM Thread Starter
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1988 XJ Cherokee 
Join Date: Mar 2013
Location: ferndale
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3 freeze plugs not 5 in new block

Hey everyone, I have an 88 XJ that needs a new engine and I purchased another 88XJ with a well running engine. Both are 4.0 (242). I pulled the donor engine and when I was power washing it I noticed the block has 3 large freeze plugs, but the original block has 5 along the drivers side. Everything else looks to be identical and I think it will work just fine but why the difference in the plugs. Both XJs are 1988. I got mine from the original owner so I know the engine is original but maybe the donor is not. Which 4.0 engines have 3 large freeze plugs?

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post #2 of 4 Old 03-19-2013, 12:43 PM Thread Starter
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1988 XJ Cherokee 
Join Date: Mar 2013
Location: ferndale
Posts: 21
I've looked around on this freeze plug issue and this donor engine may be an amc 258. Other than the freeze plugs everything looks identical. If it is the 258 will i still be able to use this engine? I want to use my original intake manifold. I think I can still do this.
Any ideas thoughts?
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post #3 of 4 Old 03-19-2013, 09:47 PM
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1990 MJ Comanche 
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Get teh numbers off the side of the block to be sure. And no, a 258 isn't a good swap.

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post #4 of 4 Old 03-20-2013, 04:16 PM Thread Starter
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1988 XJ Cherokee 
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OK, I ran the block # 8933002665 and it does come back as a 87-90 4.0 That's good news. I was basing my thought that it may be a 258 due to the only picture I have been able to find in a google search of a I-6 block with 3 big (2") and 2 small (about 1") freeze plugs was stated to be a 4.2-258. My original motor has 5, 2" freeze plugs on the manifold side OOOOO but the other motor looks like this OoOoO. Good news is the block casting # comes back to a 4.0. So I guess the 4.0 came in both freeze plug layouts although all the pictures I have looked at, tons of them, all show 5 large plugs. The motor in question is an injected serpentine set up. From what I have found on this site the 4.2 is a carbureted engine but can be converted.

Thanks for the help.
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