So my truck motor (2002 Ford F150 Lariet Supercrew) isn't coming up to temp. Only 160 degrees. I replaced the thermostat and flushed the system and new antifreeze. Even though I installed a 192 degree thermostat, it still only reaches 160. It's a 5.4 Ford. The heater core acts as the bypass and it has the resistor in the heater hose. Any ideas?

 

How are you measuring the exact temperature?

 

Infrared thermometer at the thermostat housing

 

Might be low coolant. Is the degas bottle low? If not there may be air in the system.

 

No, all that's good.