1981 CJ7 Restoration - 2023.06.15

If it isn't one thing it's another. Using the 4.6L stroker motor from Golen Engine introduces a bit of nuance. The 4.6L stroker is based on a 1992 Jeep YJ 4.0L engine and head. The block fits in a CJ7 frame, but the way the motor was configured is a little different. One of those differences is that the 1992 motor had a thermostat housing with a coolant temperature sensor port. Coincidentally, the Holley Sniper EFI system also has a coolant temperature sensor and uses it to calibrate air/fuel ratio and other adjustments. This motor came with a housing with no port, so I had to get a new one. In keeping everything looking consistent I painted it with Eastwood Aluma Blast.

The coolant temperature sensor in the thermostat housing will be used to feed information to the ECU. I also installed a new engine temperature sensor in the rear of the head which will feed the temperature gauge in the dashboard. Always learning.

Thermostat housings. 1981 CJ7 258/4.2L (left) and 1992 YJ 4.0L (right).

Just for reference, this is the correct orientation of the thermostat. One thing I did that saved me some trouble is to apply a thin coating of RTV gasket maker to the side of the thermostat that touches the cylinder head. This helps hold it in place while installing the housing/water outlet. Previously, whatever was used was applied to both sides and was so hard and cured that I just about destroyed the thermostat to remove and paint the original housing. Thankfully, I didn't have to touch the thermostat for the housing swap today.

Correct orientation of the thermostat in a Jeep 4.0L L-6 head. Same applies to the 258/4.2L head.

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