1994 7.3L DI block heater replacement
 

And a good chilly morning to you from the Pacific Northwest basking in temps below 20.

I had recently begun plugging in the block heater on my 1994 F250 Powerstroke in the hopes of making cold mornings starts a little easier. Well, after a week or so of not doing much good, I find the GFI blown on the circuit I had the truck plugged into.

I've tried it on a few different circuits in the house and in every case it blows the GFI or a breaker. Methinks there is a problem.

If I take an ohmmeter to the plug it acts like a capacitor; starts out immediately shorted, then rapidly builds to about 190K ohms.

When I traced the cable and found the block heater installed in the oil cooler fitting, I found the plug was wet (presumably from the snow as it was -not- coolant) so I dried it really well and tried again.... no change.

I believe I need to change the block heater, but how to do it. I'm wondering if this will require me to drain the cooling system or not. I would hope the heater is sitting in a thermowell but I doubt it.

Can anyone shed some advice on this problem for me?
Thank you,
Asa Jay

Follow-up
After doing more research, I found I'll have to drain the coolant as I expected. I've also found a few replacement sources, such as Napa and Amazon.

you gotta drain it, replace the heater, fill coolent and your good to go