Block heater testing - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 01-15-2005, 10:14 AM Thread Starter
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Block heater testing

Any idea what kind of current draw or resistance a typical block heater should show? I tested mine and it measures 38 ohms. To me, that seems too high of resistance. When I plug it in, there is only a tiny spark, and I don't hear the typical sizzle sound it used to make. Maybe its gone bad, or the cable is broken or making a poor connection?
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post #2 of (permalink) Old 01-15-2005, 10:47 AM
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Re: Block heater testing

I've seen block heaters with a typical 15 Ohm to 30 Ohm resistance. So, your value doesn't seem too out of the ordinary.

However, that little spark is a clue.

If there's a solder joint from the power wiring to the resistance, it often becomes a point of failure. Power goes across the joint and eventually it fails... and becomes resistant. Then when you plug in the heater the joint sparks as power can only arc across the joint to complete the circuit.

I'd pull the heater and install a new block heater and be done with it. Then you can have good geeky fun pulling apart the old one and seeing how it's constructed.
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