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TXwannabe · 12-02-2020, 10:33 AM

05 Phaeton, C-7, Freightliner chassis. As we traveled this past week from AZ to TX, we had multiple nights on the road of low to mid 20's temps. Although I probably haven't used this in 2 years, had the thought to use the engine block heater for easier startup each morning. Plugged the cord labeled 'engine block heater" into the outlet in my electric bay, went to the rocker switch on the panel adjacent to the driver's seat, turned it on, but the indicator light didn't light up.
Used my meter to determine I had power to the outlet. How can I determine if the block heater is actually working or not?

exclus · 12-02-2020, 11:29 AM

You'll know by checking engine temp on the FL digital display. You'll probably see a temp range between 80-125 degrees depending on how long you leave it plugged in. Obviously you need to be plugged in or have the gen on for 110v power to be supplied to the outlet.

Skip426 · 12-02-2020, 11:34 AM

If it's quiet enough and you're close to the engine , you'll hear a hiss from the heater after it's been powered up for a couple of mins.

alank · 12-02-2020, 05:43 PM

If you have any type of control panel that shows the current being drawn on each leg, just shut about everything down so there is very little current being drawn on either leg. Then note the amounts of current, turn on the block heater and see if one leg jumps up about 10A in current, then shut it off to see if current goes away. If it does, you have a block heater, if there's no change, you don't have one.

That's how I found out by block heater was bad from the factory.

You could also check for electrical continuity at the plug, but the wire from the plug to the heater could be bad. Then you could go to the engine block heater and check it there.

wolfe10 · 12-02-2020, 05:50 PM

And, another method is to just put your hand on the block after the block heater has been on for an hour or two.

FL420 · 12-02-2020, 06:20 PM

I use my ScanGaugeD to check my coolant temperature in the morning to see how cold it got the night before. I suppose I could use it to check to see if the block heater was doing its job.
I never felt the need to do it as my Cummins starts easily in the teens and twenties without using the block heater.