Hot wire indicator glow plugs advice

[ZZZRSC]

I found there were several people that had questions about replacing a hot wire indicator for their glow plugs and thought I would try to help. . It is called Nichrome (Nickel Chromium) wire and its been around since 1906. It was the first wire used for resistance heating elements. It is relatively inexpensive and will withstand tens of thousands of heating cycles. I used to make replacement heating elements for antique heaters. You can measure the diameter and length and order it from McMaster Carr online. Sizes from .003" to .081" Dia.($30/6'). They sell retail to anyone and are the World's largest hardware supplier. If you need larger than .081" Dia. you'll have to look elsewhere or shorten the length to lower the resistance without getting it so short it glows like a headlight .. You want the indicator wire to glow red to bright orange, but not yellow or white hot. Glow plug voltage varies by the engine brand, they can be 1.5 volts up to 24 volts on some engines. You can take them all out (and test their resistance from terminal to body ground to make sure they are good), and hook them all up to a battery with the resistance wire, then adjust length to keep the plugs a dull red color after a 10 second test.. If you coil the wire, the coil loops MUST NOT touch each other. I have made ceramic insulator rings by using a Dremel cut-off wheel (and dust mask) from old knob & tube wiring from an old electrician I know.
Feel free to ask questions, or correct me. Although I am a Master Electrician, I am only an amateur Diesel Mechanic.

 

[Roadworthy]

Interesting and informative. One might consider that often these indicators (doubling as voltage dropping resistors) do not fail. The ends become oxidized and will not conduct. They can be disassembled and cleaned then put back into use.

 

[ZZZRSC]

That's true, and if one glow plug fails open, the voltage drop across the hot wire "resistor' will decrease and the voltage to the other GP's will be higher, shortening their life. You may notice a less bright indicator also, because of less current flow through the 'resistor'.

 

[Tinhack]

That's true, and if one glow plug fails open, the voltage drop across the hot wire "resistor' will decrease and the voltage to the other GP's will be higher, shortening their life. You may notice a less bright indicator also, because of less current flow through the 'resistor'.

I've never been able to see mine glow. I turn the key to heater and count the hour meter clicks. Typically, five clicks for cool days (40-60*F). On cold days I go to 7-8 clicks. Never had a problem starting the Kenbota. Even if only one cylinder out of the two is getting heat, it will start.

I've only used the "glow plug" (singular) on the Ford a few times since the restoration (2020). I don't think it really needed it. It would start on its own in the dead of winter down here. And I mean Right Now.