Overcooling on stock set up?

[jondee86]

If the thermostat is missing, or stuck open, the engine temp will "float"
according to engine effort and the ambient temp. That means ir will be
lower on cold days, and higher on warm days. Likewise, working the engine
will raise the temp.

It is the job of the thermostat to regulate the flow of coolant and maintain a
constant operating temp. If you had a working TRD thermostat, the engine
temp should hold steady at around 73 deg.

The thermostat is located inside an alloy casting on the intake side of the
engine, on the discharge side of the water pump.

Cheers... jondee86