I installed a new Cummins block heater and cord on my 93 this past summer. I finally decided to use it today, as it was 18 degrees in SE WI. Anyways; I go to plug in the heater cord to my 10 ga extension cord, and snap! The block heater cord arched where it screws on at the block heater. Could the block heater cord be plugged in backwards - causing reverse polarity? Maybe I got a defective block heater? Any help here is appreciated!!!!

 

Reverse polarity is very unlikely. The cord should only be able to plug in one way.

The cord may have been pinched or damaged somehow or maybe the pins in the block heater got shorted out.

Are you sure that your 10 gauge extension cord and the socket that it is plugged into are OK?

All I can think of, its way late for me,
JP.

 

Sounds like somethings shorted out. I don't think the polarity on the heater should make a difference. Maybe take a volt meter and see if its shorting out to the block. something may have rubbed thru. I almost never use mine. The only time is at work but I have not had a chance to scope out a new plug location at the new place.

 

Did You test it when You first installed it? If not then after a few months the cord may have shorted.

 

All;
Thanks for the great input! No i didn't check the Cummin's block heater or cord. I should have! As mentioned; they were both new, so I figured that they would work. Live and learn! My 10 ga extension cord is in good shape. What reading am I looking for on a volt meter (on the heater and cord). I am guessing that the block heater element is touching the block?

 

When checking ohms on the heater element, there should be 0 on that. There should be 120v to the element when energized. I don't think that the heating element touching the block should be a problem, as long as there's water surrounding it.

 

Thanks for the info on the ohms readings! I hope my element on the block is not bad! There is antifreeze in the block. I can live with a cord replacement. I really don't want to change out the block heater in this cold weather