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Discussion Starter · #1 ·
My retirement motor is finally in, 258, Crane Torquer Cam, Mopar Performance lifters, 4.0 head with the water jackets bored, tapped, plugged, milled, Holley T/A 470, power steering, and the Team Rush ignition cdi upgrade. The temp sending unit is the same out of my 258 that ran 190 all of the time. This one is mounted in the same rear part of the 4.0 head and I'm running at 250*.



I'm wondering with the water jackets sealed up in the 4.0 head. Does it run hotter in the rear location and is there a better location for the sending unit??? The thermostat is opening because the radiator does get hot, but doesn't seem to be over heating hot and it was 40* outside today.
 

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Discussion Starter · #6 ·
I bought the CJ new in 79 so all motor part bought for this motor were also for a 79. I don't have a thermal gun to check the hoses, I used my hand.
 

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Discussion Starter · #7 ·
Since it is raining today, I did get a thermal heat gun and the radiator cap was seeping. The parts house is getting one so I will try that tomorrow.
 

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Discussion Starter · #8 ·
I used the thermal gun on the motor today, Top tank on the radiator 190, thermostat housing 192, down the passenger side of the head 195 to 202 back at number 6. Drivers side of the head / exhaust side 260 at the front to 250 back where the sending unit is.

Where is everyone mounting their sending unit???? Looks like I should move it to the thermostat housing.
 

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Discussion Starter · #10 ·
I have an 85 and 86 both with the mopar mfi kitsch. The 86 I installed a 4.0 head and it does run hotter than the 85 or what it did with the 4.2 head.
Seems like the exhaust side of the head is hotter and the spark plug side seems to be fine. I'm just guessing with some of the water jackets plugged off it would be normal???
 

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Discussion Starter · #12 ·
If I need a second reading or I need to put in a mechanical gauge I put the sensor in a thermostat housing from a 4.0HO. The 4.0 had 2 sensors, one for the gauge (back of block) and one for the PCM which was on the thermostat housing.
A second gauge at the thermostat housing will be my next move. That will give me a reading over the whole motor. The rear of the head with all of the water jackets plugged along the manifold side looks to run about 250* while everywhere else is ok.

She is at the exhaust shop now getting the exhaust hooked up and snow tomorrow we will see how much more I get done.
 

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Discussion Starter · #13 ·
A second gauge at the thermostat housing will be my next move. That will give me a reading over the whole motor. The rear of the head with all of the water jackets plugged along the manifold side looks to run about 250* while everywhere else is ok.

She is at the exhaust shop now getting the exhaust hooked up and snow tomorrow we will see how much more I get done.
 

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Discussion Starter · #14 ·
The water pumps are about the same, the only thing is. I think the new pump could have been tighter, so I will try again tomorrow.
 
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