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post #1 of (permalink) Old 12-30-2001, 05:48 PM
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258 temp vs. 4.0 temp

I have a question about running tempís for a 1980 258 vs. a 1993 4.0 I did a swap and if I remember right the 258 used to run on the stock gauge at just under the half way mark. Since the swap, (Iím using the same gauge from the 1980 Jeep) the 4.0 runs just above the half way mark. I know that the 4.0 is suppose to run at about 210 degrees Does this sound normal to those of you who have made this swap??

Thanks John

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post #2 of (permalink) Old 12-30-2001, 08:56 PM
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Re: 258 temp vs. 4.0 temp

So i think, the 4.0 is running on the older gauge? In a cj, with the stock gauge?
If this sounds right then your probably ok. The 258 should probably have run around 185-195, i believe. Whereas your correct about the 242 running at 210.
i would get an after market gauge and be sure.

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post #3 of (permalink) Old 12-30-2001, 11:43 PM
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Re: 258 temp vs. 4.0 temp

I dont know about the 4.0, but my stock '83 258 runs at 190 when it is blistering hot out, and it creeps up to 180 when it's winter time (like now...it's 6 degrees out). This is on an Auto Meter gauge.

Mike H.
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post #4 of (permalink) Old 01-01-2002, 06:04 PM
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Re: 258 temp vs. 4.0 temp

A 4.2 uses a 195 degree thermostat, and a 4.0 is a 192 degree unit. 3 degrees doesn't mean much, So, both engines should run at around 200-215 (210 seems to be the average)
I'd verify the the temp with an accurate thermometer, but chances are your old engine had the wrong thermostat, people love to mess with them. [img]/wwwthreads_images/icons/smile.gif[/img]
Another thought is that you may have a better ground connection now and the guage is now reading normal, but was reading low with the old engine and crappy ground connection.
The halfway point on the guage is about 195, so if it's working correctly, you're probably around 210, which is perfectly normal for a 4.0.

-Derek Schwab
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post #5 of (permalink) Old 01-01-2002, 06:32 PM
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Re: 258 temp vs. 4.0 temp

Did you by chance change out the sending unit like unit to like gauge. There may be a diff between the 80 and 93 sending units, one is computer linked the other is not. They used both styles in 93 and used only the none linked in 80. By linked the sending unit talks to the computer then the gauge and the other does not. This may or may not be your difference.

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