We use very high quality glow plugs in our heaters, that very rarely, if ever, fail. Over the past winter we really did not replace even one glow plug for our customers in support.
The problems we see with glow plugs, are typically not with the glow plug itself, rather the power supply not beign able to supply sufficient amperage required for the glow plug to get red hot.
The glow plug only heater up during the starting cycle of the heater and goes out once the heater has created combustion and the flame is kept alive by the fans and the fuel pump only.
We have two revisions of glow plugs:
- White wires, blue cap: This is the more common glow plug type found on our heaters. This glow plug is held in by a small set screw, which can be turned 180 degrees to allow the glow plug to be removed.
- Green/Yellow wires, black cap: This is a less common glow plug version in our heaters. These glow plugs are screw in (no set screw) and harder to remove/replace without taking the heater apart by removing the fan assembly.
In General, Do Not Remove Glow Plug
We see a lot more glow plugs and heaters damaged attempting to remove the glow plug than we see actual issues with the glow plug. Meaning, if it ain't broken don't attempt to fix it.
In general, you should not need to remove the glow plug. If you suspect it is not heating the best way to test a glow plug is to look for higher amperage draw while starting up the heater while the glow plug is heating. During the first approx. 45 seconds after starting the heater you should see around 6-12 amps being drawn by the heater. This high amp draw indicates the glow plug is heating.
Additionally, if you are seeing white smoke out the exhaust during startup attempts, this typically means the glow plug is getting hot and burning off fuel creating the white smoke.
If you are unable to monitor for amperage draw, then you could remove the glow plug and see if it gets red hot attempting to start the heater with it out. But this is risky removal, and risk of burning, use protective gloves. Glow plug heats to over 2000 degrees f.
If you have the white wires with blue cap glow plug, DO NOT unscrew the set screw all the way. You run the risk of losing the ball bearing inside the heater which will require full disassembly to retrieve.
Common issues with glow plugs:
- Main heater power wires are extended to reach battery without wire extension being upsized accordingly to prevent amperage loss over distance. This causes the glow plug to not get red hot enough to combust the atomized fuel.
- Heater power source no providing sufficient amperage for glow plug to get red hot. We see this when our heaters are powered by portable power stations with 10amp or below amp rating on the ports that power the heater. Ideally, our heaters require 15+ amp rated power ports to enable the glow plug to get hot enough for proper ignition/combustion.
Photo showing green/yellow/black glow plug how it is screwed in. These are typically finger tight but you can see it is a delicate operation. Regular threads unscrew lefty loosy.
