Thoughts on Quick-Connects for Block Heater Cord?

[DennisG01]

I suspected my block heater wasn't working - couldn't hear it when I plugged in. I put my meter on the the two prongs (not the ground prong) at the cord end (opposite of heater) and got 8.5K. Hmmm I thought. I expected to see infinity. However, I'll admit that I don't know what it should Ohm at. Anyone know?

Still confused by this reading, and even though there's snow on the ground, I figured I should go under and check the connection at the actual heater. Guess what? The cord was sheared off at right at the plug end (the end that connects to the heater) and just hanging loose!!!! What the heck?!?! This cord is only about 4 years old. I wiggled the plug-end out and looked at it - the orange rubber was disintegrating/crumbling in my fingers!

Could the plug end have been sheared by improper engine replacement? Or, could this crumbling be considered normal? Any thoughts on that?

OK, to my original question....

I have a permanently installed (in bumper) plug-in for the heater. I'd like to avoid taking that apart - especially if these cords naturally disintegrate and I'll have to replace it again.

So, I'm thinking of using some quick-connects somewhere in the middle of the cord in a convenient location. Should I just use bullet-type connectors and shrink? Or, is this there something better? I believe the heater is about 600w - maybe 800w? If so, would 14 gauge connectors be fine (if my googling ability is up to parr, anyways:rolleyes5:)???

[JohnC]

Adding more connectors will compound the problem. Get a new cord, clean the contacts on the heater and apply a liberal amount of dielectric grease to the contacts when installing the new cable. Water gets into the connection, causes corrosion which creates resistance which creates heat which causes the problem...

If it's good it should read near zero, not infinity, with the Ohm meter. Infinity is an open circuit.

[DennisG01]

Well, out of all the causes for this that I've been thinking about, that makes the most sense, John. When I get the new plug and take the old one out, I'll post a pic of what it looks like.. just for fun. I'm leaving the "stub of a plug" on the heater for now, to keep dirt and snow off the heater's prongs.

I wasn't very clear above in regards to the resistance. I expected to see infinity because I assumed something was wrong with either the cord or the heater. The 8.5K threw me. Looking back, even the cord was no longer attached to it's heater plug end, there must have been a few strands contacting each other.

General question: Would all types of heater elements test at near 0 when good? How do they make heat if there is no resistance? Although, what you say makes sense because I know that glow plugs test near zero when good. Or, in the case of glow plugs, is that 1.5 Ohms all that is needed?

[JohnC]

I expected to see infinity because I assumed something was wrong with either the cord or the heater.

OK, that makes sense.


The 8.5K threw me. Looking back, even the cord was no longer attached to it's heater plug end, there must have been a few strands contacting each other.

Could be corrosion, too, which is slightly conductive. Even a single strand, making good contact, would Ohm out close to zero.


Would all types of heater elements test at near 0 when good?
A high current AC heater with no thermostat will have a DC resistance close to zero.


How do they make heat if there is no resistance?
The AC resistance (impedance) is more than zero. A 1200 watt heater will have an impedance at 60 Hz of 12 Ohms. The DC resistance will be a little less than 12 Ohms.


Although, what you say makes sense because I know that glow plugs test near zero when good. Or, in the case of glow plugs, is that 1.5 Ohms all that is needed?

Yes. 1.2 Ohms on a 12 Volt DC system will draw 10 amps and that's 120 Watts.

[DennisG01]

Thanks, John! I appreciate you taking the time to explain it better for me.