Another mystery sensor

Oil cooler is a oil to water heat exchanger. The 2 metal coolant lines that run in back of the valve cover go to the oil cooler and one of them has a small bung for the coolant hose that goes to the bung at the center of the lower intake to provide coolant flow for the ECT sensor. If this small hose in not present, or the coolant passage blocked off to try to keep the intake cooler, the ECT must be relocated somewhere, such as a heater hose, so the PCM will get accurate coolant temp readings.

Oil cooler is a oil to water heat exchanger. The 2 metal coolant lines that run in back of the valve cover go to the oil cooler and one of them has a small bung for the coolant hose that goes to the bung at the center of the lower intake to provide coolant flow for the ECT sensor. If this small hose in not present, or the coolant passage blocked off to try to keep the intake cooler, the ECT must be relocated somewhere, such as a heater hose, so the PCM will get accurate coolant temp readings.

Ah I see; there was a hose running to the bung on the center of the lower intake but this hose ran to the supply line from the heater core. Basically, there's the hose/hardline combo that runs from the water pump to the heater core inlet. Right before the heater core inlet, there's a t fitting with a hose that runs to the bung on the lower intake manifold. You can actually see the t fitting in the original picture. I'm assuming that this was a modification by the previous owner to account for the ECT sensor.

With that in mind, I think I will loop the water pump and thermostat together and have a t in there that will supply coolant for the turbo and ECT sensor.

Sounds like that will work!