It has come to my attention that there has been a few instances of glow engines cold starting (a warm glow engine that starts even though there is no battery hooked up to the glow plug) and even some injuries because the person choking the engine was not expecting the engine to start. Yes, this could happen if a person passes by a plane that has been recently run and flips the propeller on that airplane.

This is usually caused by a hot engine being choked and the propeller being flipped. This is not a common problem, but all modelers should be aware that this problem does exist. I have talked with several experienced people about this rarity. I spent quite a while talking with Jim Gerard of Gerard Enterprises.

Apparently there is a catalytic reaction between the methanol and platinum in the glow plug. Usually the engine has a high compression ratio and has been recently run. If conditions are just right the engine could fire just from the compression of the engine. Jim does not recommend the use of WD-40 to aid in starting an engine. He has seen diesel airplane engines fire on WD-40 alone. He also thinks that high carbon build-up could glow for a while after a run. One remedy is to let the glow engine cool down before restarting.

While chances are remote that the engine will start without the glow plug hooked up to a battery, one should consider the possibility hat this can and does happen. It also seems to be more frequent on hot and muggy days. Someone once told me that the safest way to leave the engine is with the glow plug out and the propeller off. Engines I am aware of that have cold started are .40 size racing engines, Supertiger (2000, 2500, 3000) and Moki 1.8.

Jim recommends that when choking the engine, you BRISKLY flip the propeller three times and flip the propeller three more time before connecting the battery to the glow plug. Then close the throttle to about žth open and then connect the battery to the glow plug. Flipping the propeller in this way will most likely have you in a position to avoid the propeller should the engine start running. Jim also says it is much safer to back flip the propeller instead of flipping it in the conventional way. He also recommends a chicken stick or turning the spinner. He also carries this warning: "Be very careful when choking a hot engine, it is possible for the engine to start even though the battery is not connected!"

Here are the safety tips Jim includes with his instructions for the Moki 1.8 glow engine:

• Keep small children and anyone else who might be hurt a good distance away when running your engine.
• Be sure that your engine is properly mounted in its test stand or airplane so that it cannot vibrate loose.
• Keep your face and body away from the path of the prop as you start and run your engine.
• Use an electric starter or a "Chicken Stick". Keep your hands away from the prop as much as possible.
• To stop your engine, cut off the fuel supply or adjust the throttle to close off the air supply.
• Never throw anything into a running engine to stop it.
• Discard any props with nicks, scratches, splits, cracks or any other signs or wear or damage.
• Never alter, repair, bend or shave a prop.
• We recommend that you use safety glasses when starting or running your engine.
• Do not run your engine in an area containing loose gravel or sand.
• Avoid loose clothing that could become caught in the prop.
• Make certain that the glow plug wire is out of the way of the prop.
• Keep all of your engine fuel in a safe place, away from any danger of sparks or excessive heat.
• Do not smoke while working on or running the engine, or while handling the fuel.
• Model engines develop considerable heat. Do not touch any part of your engine until it has cooled.
• Never run your engine in an enclosed place (garage, basement, etc.) carbon monoxide is deadly!

Almost all of these tips also pertain to gas engines. Larger gas engines usually require a starter or a heavily gloved hand due to their great compression. A chicken stick should be covered with a heavy foam or rubber so it won’t damage the prop.

Manufacturers mentioned in article: Gerard Enterprises