How to tell if block heater is working?

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Carnoobie

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I just replaced the plug cause one of the ends on the plug broke, it split right open. So I picked up a new plug, cut this one off, spliced the wires and connected to the terminals.
I have to say this job was a major pain in the [censored] cause the plug I bought is a cheap POS.

The only thing is, it says connect black wire to brass terminal and white to silver terminal. So there should be 1 black wire, 1 white and 1 green. I have 2 black and 1 green! So i connected 1 black to the brass and the other black to the silver.

If it doesnt work, then ill have to reverse them. But i want to know whats the best way to tell if its working? Because from what i know, my block heater doesnt make any noises when plugged nor does it feel warmer.
 
Plug it in and see if it is warm. I would guess anything above 50 degrees would be good enough.

It shouldn't matter which way you connect the wires. The heater is a giant resistor and it cares not which direction the electrons flow.
 
Originally Posted By: Loobed


Plug it in and see if it is warm. I would guess anything above 50 degrees would be good enough.

It shouldn't matter which way you connect the wires. The heater is a giant resistor and it cares not which direction the electrons flow.



So it doesnt matter if the black and white cables are backwards?

I know for car audio it does matter
 
Last edited:
Test the coolant temp after it's been parked all night. Turn the heater on and test again after a couple hours.
 
Originally Posted By: Carnoobie
Originally Posted By: Loobed


Plug it in and see if it is warm. I would guess anything above 50 degrees would be good enough.

It shouldn't matter which way you connect the wires. The heater is a giant resistor and it cares not which direction the electrons flow.



So it doesnt matter if the black and white cables are backwards?

I know for car audio it does matter


It will work, but there is a reason one is black and one is white. It's a system of hot (black) and neutral or return (white), recognized and followed throughout home and commercial wiring practices. The maker of that heater also undoubtedly designed the device for the polarity not to be reversed.

Any exposed metal parts attached to the neutral, which are supposed to be attached to the neutral, may now be accidentaly attached to the hot side because of what you've done with the plug. Electrocution can happen - especially on ungrounded items.

Liklihood of that happening is probably low, but it really needs to be done right. As I said...there's a reason a system like this exists.

Edited to add: I really like an engine heater and have had them on two cars now. Yes, synth oil is probably all I need for my Chicago winters but I just enjoy the idea of easier start-up, less wear and quicker warm-up. They can be a pain, though. I've forgoteen mine was plugged in once and ripped the cord right out by the root. No fixing it, had to get a new heater. I use a timer inside my garage and only need three hours on the coldest of nights. Outdoors I'd operate it overnight.

Feel around under the hood after the thing has been plugged in for a while. The warm coolant will spread through at least one of the hoses. You really can't miss it if it's working.
 
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Originally Posted By: KlooksKleek
Originally Posted By: Carnoobie
Originally Posted By: Loobed


Plug it in and see if it is warm. I would guess anything above 50 degrees would be good enough.

It shouldn't matter which way you connect the wires. The heater is a giant resistor and it cares not which direction the electrons flow.



So it doesnt matter if the black and white cables are backwards?

I know for car audio it does matter


It will work, but there is a reason one is black and one is white. It's a system of hot (black) and neutral or return (white), recognized and followed throughout home and commercial wiring practices. The maker of that heater also undoubtedly designed the device for the polarity not to be reversed.

Any exposed metal parts attached to the neutral, which are supposed to be attached to the neutral, may now be accidentaly attached to the hot side because of what you've done with the plug. Electrocution can happen - especially on ungrounded items.

Liklihood of that happening is probably low, but it really needs to be done right. As I said...there's a reason a system like this exists.


But my cable has 2 black cables and 1 green, no white. So how do i figure out which is black and white?
 
To test a block heater you plug it in and wait 10-15 seconds. If It is working, you will hear a faint sound like a tea kettle. No need to wait for hours to feel if it gets hot.
 
Get a kill-a-watt meter. If it's using watts it's working. They have them at libraries.
 
Originally Posted By: Carnoobie
Originally Posted By: KlooksKleek
Originally Posted By: Carnoobie
Originally Posted By: Loobed


Plug it in and see if it is warm. I would guess anything above 50 degrees would be good enough.

It shouldn't matter which way you connect the wires. The heater is a giant resistor and it cares not which direction the electrons flow.




So it doesnt matter if the black and white cables are backwards?

I know for car audio it does matter


It will work, but there is a reason one is black and one is white. It's a system of hot (black) and neutral or return (white), recognized and followed throughout home and commercial wiring practices. The maker of that heater also undoubtedly designed the device for the polarity not to be reversed.

Any exposed metal parts attached to the neutral, which are supposed to be attached to the neutral, may now be accidentaly attached to the hot side because of what you've done with the plug. Electrocution can happen - especially on ungrounded items.

Liklihood of that happening is probably low, but it really needs to be done right. As I said...there's a reason a system like this exists.


But my cable has 2 black cables and 1 green, no white. So how do i figure out which is black and white?


If two black wires then it doesn't matter
 
Originally Posted By: Carnoobie
Originally Posted By: KlooksKleek
Originally Posted By: Carnoobie
Originally Posted By: Loobed


Plug it in and see if it is warm. I would guess anything above 50 degrees would be good enough.

It shouldn't matter which way you connect the wires. The heater is a giant resistor and it cares not which direction the electrons flow.



So it doesnt matter if the black and white cables are backwards?

I know for car audio it does matter


It will work, but there is a reason one is black and one is white. It's a system of hot (black) and neutral or return (white), recognized and followed throughout home and commercial wiring practices. The maker of that heater also undoubtedly designed the device for the polarity not to be reversed.

Any exposed metal parts attached to the neutral, which are supposed to be attached to the neutral, may now be accidentaly attached to the hot side because of what you've done with the plug. Electrocution can happen - especially on ungrounded items.

Liklihood of that happening is probably low, but it really needs to be done right. As I said...there's a reason a system like this exists.


But my cable has 2 black cables and 1 green, no white. So how do i figure out which is black and white?


Is the color of one of the metal conductors inside the black insulation different from the other? Or is there a thin, white line running the length of one of the black coverings?
 
[/quote] If two black wires then it doesn't matter [/quote]

Indeed, probably not, if there's absolutley no other indication that there's anything other than two blacks and a green. Looks like he's fine.
 
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Originally Posted By: KlooksKleek

Is the color of one of the metal conductors inside the black insulation different from the other? Or is there a thin, white line running the length of one of the black coverings?


I looked closely and no both are exactly identical.
 
Originally Posted By: Carnoobie
Originally Posted By: Loobed


Plug it in and see if it is warm. I would guess anything above 50 degrees would be good enough.

It shouldn't matter which way you connect the wires. The heater is a giant resistor and it cares not which direction the electrons flow.



Car audio is DC voltage. Your block heater would be plugged into you AC house electricity.



So it doesnt matter if the black and white cables are backwards?

I know for car audio it does matter
 
It's a resistor, it doesn't matter which way you hook it up-just make SURE the green wire goes to the terminal that is connected directly to the block. When you plug it in & apply power you should hear a slight boiling or sizzling noise coming from the block, and it should get warm around the heater pretty quickly.
 
Look at the old plug you cut off and look at the prongs that plug into the electrical outlet. Are they both the same size, or is one bigger than the other? If they're the same size, it doesn't matter which wire goes where. If one is bigger than the other, the wire that was connected to the small prong goes to the brass terminal and the wire that went to the big prong goes to the silver terminal.
 
It's fine. On most other things you'd use that plug for, the white wire would go to the wider prong. Since this is just a simple heating element, it doesn't matter.
Depending on the wattage of this heater, you may need to get a better plug.
 
Originally Posted By: exranger06
Look at the old plug you cut off and look at the prongs that plug into the electrical outlet. Are they both the same size, or is one bigger than the other? If they're the same size, it doesn't matter which wire goes where. If one is bigger than the other, the wire that was connected to the small prong goes to the brass terminal and the wire that went to the big prong goes to the silver terminal.


Let's say one of the prongs is larger--probably is, almost all devices have polarized plugs these days--how can he tell which wire was connected to which prong? He has already cut the plug off the wire and is now faced with what he says are two identical black wires. I don't see how he's possibly going to tell now that the cut has been made.

He's probably just going to have to go with the advice of at least a couple others here on this thread who just said to wire it up and use it. We know it's gonna work, even if it might not be the absolute safest. And there might not even be any risk at all, depending on how the device was engineered.
 
Shine a laser thermometer at it...that will tell you if it's warmer than the surrounding block.
 
Sometimes, we miss the obvious answer. When I have had bad block heater cords, I don't do the "splice the plug" thing. I go to the parts store and buy a new cord. They plug right back into the block heater. If they go in only one way, then the polarity issue is solved. If they go in either way, then polarity likely isn't an issue. With a proper replacement cord, there's no concern as to whether the plug is sufficient for the current.

Of course, the block heater isn't always easily accessible, but in my experience, it's been easier than messing with splices.
 
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