Block Heater Plug

Had a bit of a shocking experience the other morning before work. Nighttime lows have been in the low 20’s, so I had my block heater plugged in.

Started my day with 110 volts of alternating current going through my hand!

No more block heater until I have a chance to examine & repair the cord.

Luckily, at these temps I don’t need the block heater to start. That being said starting the engine with coolant that is preheated to 100 degrees Fahrenheit means I can get heat in the cabin before I leave the driveway. Without the block heater it takes about ten minutes to heat up the coolant enough to warm the cabin.

Found a small hole in the insulation just after the plug. I wouldn’t be at all surprised to learn that the hole was chafed into the insulation by the cover that protects the blades on the plug.

Went to the Orange Store to look for a replacement end and found this guy.

Package states that it’s waterproof and I believe it. The cord enters through a rubber grommet which is compressed when you screw the black end onto the plug. There were four grommets in the package, I used the smallest one.

I cut off the old plug as close as possible to the end, as I didn’t want to shorten the cord any more than I had to. Then I put all the pieces onto the cord from back to front :

Black end – clear bushing – rubber grommet – yellow body.

1. Strip the three conductors.
2. Screw them into the terminals
3. Push plug end into yellow body, aligning key way.
4. Screw plug end into yellow body.
5. Slide grommet into yellow body.
6. Push bushing onto grommet.
7. Screw black end onto yellow body

Once you screw that black end on, you can feel the rubber grommet compressing. I’m not at all concerned about water weeping into this plug.

Because this plug is so large, I had to trim some of the split loom back.

Next time this wire chafes away (hopefully another 18 years), I’ll probably see about mounting the plug into the front bumper so I can just push the receptacle end of the extension cord into the bumper, something like the shore power connection on an RV.

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