redramnc

finally had to plug in over Thanksgiving. Was up in mountains at my parents house and had it plugged in for several days until one night it popped the breaker. Got home, went to plug it in where it has been being plugged for 5 years and it trips GFCI. Searched and read many posts on block heaters then went out and checked everything. My very expensive DMMs say it is 20.4 ohms total hot to neutral on the plug, ground is isolated. Heater itself is 19.4 ohms best I can tell (splint on right index finger makes it hard to hold 2 leads in position for very long). I changed the male plug on cord due to age cracks in wire jacket at plug. No corrosion found in wires. New Hubbell male end installed, still 20.4 ohms and tripping GFCI. Cleaned heater plug end contacts and plug pin and housing as best I could. Any ideas from the collective? What is the possibility that the heater element is bad but still within range? Hate to start changing things without knowing what is actual problem.

I think I am going to install the Marinco male socket in the bumper regardless of what I have to change to get it working. Overton's has them for $19.

infidel

My bet is the problem is the GFI.
They tend to trip at a lower amperage every time they trip.

redramnc

After 5 years of being plugged in to that GFCI circuit why would it suddenly start tripping it? And the fact that it was good for a few days/plug in cycles at my parents house then blew their non-GFCI breaker seems to me like something went south up there. But all the resistances check out OK, no corrosion found. Since GFCIs are touchy on ground-to-neutral currents I am tempted to take the ground wire out of the plug and hook an ammeter into that loop to see what is going on.

If it was the heater going bad I would think the element would go open, not show good resistance.

Replacement heater is only $23, cord is $31. Will try heater first, I reckon.

Before I replace the heater I am going to play with it some more.

redramnc

Got the motor hot and rechecked everything. Got 3Mohm N-G, 12Mohm H-G, and 19.3 ohms H-N. Disconnected ground, replugged it and did not trip the GFCI as expected. BUT - it now had 68Vac H-G, 54Vac N-G, and 118Vac H-N (ground being the power side of the plug, not the truck ground). 218K miles so it was probably time anyway. Good excuse to change antifreeze.

Heater is on order as of this morning so I will just park it till the parts get here. Supposed to be the coldest of season so far this year tonight, low 20's. Reckon I will be scraping windows on the wife's old Jaguar in the morning

The splint on my finger is really starting to be annoying, especially with this to do.