Weird coolant / over heating problem

[nmehdikh]

I did the garden hose flush method, without the radiator connected. Pulsed the motor a few times. Kept it up until it clear water was coming out. Then went about changing the waterpump.

Not much crud came out of the motor, and the water flows great through the block. Changed the waterpump as well. The waterpump was in decent condition when I pulled it out. Cast impeller and no visible pitting or anything.

Still haven't had a chance to test drive it as the rear suspension is currently in pieces. But I had another question, regarding the gauge sending unit. It is currently tapped into the thermostat housing, on the bottom side. So on the "hot" side of the thermostat. Doesn't that mean I'll get varying temperature readings based on load, regardless of what the radiator is doing? As the motor is revving, and producing more heat, the coolant takes that heat, directly past the sending unit, then to the radiator for cooling. Then after its cooled, it flows through the block to be heated and then back to the temp sensor. So no matter what it's seeing "fresh" hot coolant. Or am I missing something here?

[Miles]

I did the garden hose flush method, without the radiator connected. Pulsed the motor a few times. Kept it up until it clear water was coming out. Then went about changing the waterpump.

 

Not much crud came out of the motor, and the water flows great through the block. Changed the waterpump as well. The waterpump was in decent condition when I pulled it out. Cast impeller and no visible pitting or anything.

 

Still haven't had a chance to test drive it as the rear suspension is currently in pieces. But I had another question, regarding the gauge sending unit. It is currently tapped into the thermostat housing, on the bottom side.  It is right where it is supposed to be.  The concern is with the aftermarket Temp Gauge - did the PO install  the sending unit that came with the gauge (correct) or did he just hook it up to the stock Datsun sending unit (wrong)?  This is why we asked for the temp readings.  So on the "hot" side of the thermostat. Doesn't that mean I'll get varying temperature readings based on load, regardless of what the radiator is doing? You are over thinking this, and falling down another rabbit hole. It is where the engineer designed it to be.  As the motor is revving, and producing more heat, the coolant takes that heat, directly past the sending unit, then to the radiator for cooling. Then after its cooled, it flows through the block to be heated and then back to the temp sensor. So no matter what it's seeing "fresh" hot coolant. Or am I missing something here?