RC engine glow plugs

RC glow plugs


Radio control engine glow plugs or shortly called RC glow plugs are one most important element on your nitro engine.  The nitro engines are commonly running on the methanol- based fuels and with the adding of lubricant plus a portion of nitro methane it is an ideal fuel to power your model engines.  The glow plug itself consists of spiral-wired platinum element which is installed in the top part of the engine or on the head of the combustion chamber.


Post D



The engine operates when the volume of air is compressed to thePost A maximum point at the TDC (Top dead center) of the cylinder while the heat is applied to the glow plug via the initial supply of 1.0 -1.5 V.  At this moment the combustion takes place but the heat is still remaining on the glow plug for next cycle of power stroke so it is practical to remove the power supply or glow plug igniter from the glow plug once the engine is automatically running on itself.




Post CHaving some device to add the power to the glow plug during the flight is a good idea because the amount of fuel always varies upon the amount of throttle applied. In some case a rich moment with bad glow plug may cause the engine to stop running.  To prevent the engine from suffocate with rich mixture during the flight a tool called glow plug driver that includes boosting feature is normally used. If you want to find out about this product please visit this link: http://howtorcplane.com/glow-plug-driver



A four stroke engine has one exhaust cycle that no combustion takes place which is interesting since the glow plug must maintain the heat long enough for the next combustion cycle.  In this case the type F glow plug has been designed for the four stroke engine.  The two stroke engine is suitable for another type of glow plug – the number eight is mostly used – but there are so-called cold type and hot type of glow plug that gives different idle revolution and are used for some purposes.


Knowing the glow plugs condition


After being used for sometimes your glow plug must be removed for a periodical check. This calls for the observant technique we are going to learn from here. The engine always tells you the story of the engine through the glow plug since the condition that appears on the glow plug is a good indicator of how well you tune up your engine. There are many scenarios we could study to properly use the glow plug and optimize its capacity.  Here are the knowledge for you.


Post EThis image tells you that your engine is in good condition. It still has a nice clean look of the spiral-wired element like a brand new one. This implies a perfect mixture in the engine combustion and you would surely fly the plane in a normal practice rather than being an aggressive fighter. As this glow plug looks more like an early aging your engine tune up is fine and it will be in service for longer hours.





Post FWhen the engine is too lean for long time the heat is gradually make the spiral coil drop inward the glow plug body. This is the overheated condition which can also shorten the glow plug life and may results in the engine failure during flight. If this condition happens on your glow plug you would better change a new one and tune your engine in a rather rich side for the next engine run up.



In contrary if the mixture is too rich the nitro carbon will be accumulated on the glow plug element. This causes inefficient combustion and results in less engine power. In such case the glow plug element or the spiral coil will looks dirty and thus the heat will not be generated to the maximum point. There is no way to optimize your engine power from this glow plug so changing a new one is absolutely recommended.




Post HThis glow plug has rather white spiral-coil heated element which means the mixture is fine however the outer rim was burnt a lot. Obviously this can be analyzed in two folds that is your engine is overheated from too lean mixture or alternatively you have this glow plug in service for much longer time but the mixture is fine. If the latest case is prevailed you better change a new one but if this is not a case you need to fine tune your engine to a rather rich side.



These physical indicators tell that you need to change a glow plug.


A:  When noticed of twisted or mangled glow plug element.  This was due to an excessive heat condition that causes the spiral-wired platinum element to weaken it strength and recede inside the body.

B:  When small particle built up or attached on the heat element.  The tiny pieces of the aluminum that attached to the element will severely hinder the good operation of the glow plug.

C:  When the spiral coil is no longer shiny but is dull in a white powder color. This condition is an aging on glow plug since the catalytic reaction was extensively produced for long time hence making a shiny spiral coil to look dull.


The operations indicators that suggest you need to change the glow plug.


A:  The glow plug does not light up when applying the glow plug igniter.  This indicates that the wire is broken.

B:  The glow plug lights but fail to giving the heat after the igniter is disconnected which means the engine quit after removing the glow plug igniter.  This case is result from the built up of microscopic particles as mentioned above.

C:  The glow plug lights but the engine can not reach full RPM as it was used to. The aging glow plug is highly caused this situation as the catalytic reaction takes place so much the glow plug element becomes white powder color and thus hinders the maximum heat to generate highest engine revolution.


Those are the tales behind the operation and physical review of the glow plug. Once you are in the real treat of your engine you will agree that the glow plug will be one of the key factors that optimize the power for your RC engine.  Having time to check the glow plug regularly always keeps your engine in a good health and ensures the safety during the flight.  If you have any question or discussion please feel free to leave a message in the comment box. Thank you for your reading










2 thoughts on “RC engine glow plugs

  1. This is such an AWESOME article on radio controlled engine spark plugs, and I have learned a great deal of knowledge here 🙂

    My Dad currently has a radio controlled plane and love watching him fly it down the field, but he never lets me have a go 🙁 lol.

    But he did let me help him to build it 🙂

    Thanks also for showing me the different conditions of glow plugs, and this will be most helpful for RC plane enthusiasts.


    • Nice to know that you are interested in RC flying and thanks for the comment. Every now and then the website is adding in more interesting content so please visit “howtorcplane” from time to time to check out a new stuff

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