A simple and quick way to test the block heater is with a continuity test. Use a meter to test for continuity by connecting a lead to each blade of the plug. It should show a closed circuit. If you don't have a meter, you can use a 12 volt test light: clip your "ground clamp" to the positive post on the battery, touch the probe to one blade of the plug while grounding the other blade. If it lights, the heater is good. If not, the element is burned out, the cord is unpluged from the heater, or the cord is defective.

 

It sure ain't! Bwaaahahahahaha!!!!!!! It was -39°F here actual temperature, no wind, this morning, and I can guaran-****-tee ya that the grid heater still comes on with the block heater plugged in! Yes, in WARM (tropical) weather like 20°F it won't, but that's because like was said, the block heater can warm the manifold temp to 65°.

And..........anyone that has the idea that a block heater is going to give them instant heat from the heater has never experienced cold weather. I ran for 2.5 hours at 60mph this morning before the engine even came past 150°. Never did get up to full heat even after 5.5 hours.

Oh......on checking the block heater..........ohm meter. 750 Watts/120 Volts = 6.25 Ohms you should have between flat prongs.

 

I use a infrared thermometer to check my heaters periodically. So easy....

 

After I unplug and start her up the grid heater will cycle. The pig tail light on the inst. cluster does not come on though. I can watch the volt Gage and see the cycling. Temps have been in the single digits.