Troubleshooting in the key of A Major

If you've come to this page expecting nitro engine troubleshooting,the heading above is correct. Nitro troubles are seldom related to air leaks, defective engies, or other unseen gremlins, they are almost always related to a misdiagnosed tuning condition or an actual mechanical problem that is affecting engine performance and only LOOKS like a tuning problem. In any case, I hope this page helps you find something you've overlooked.

An important point of tuning that should be mentioned is effective lubrication and engine temperature. As you enrich a fuel mixture, you are supplying more lubrication; as you lean it out, less. The leaner an engine is, the higher the engine temp is likely to climb; richer, the temperatures will drop. Correct tuning is a delicate balance between engine performance and adequate lubrication to avoid overheating.

Correct engine temperature is a highly debated topic, but the bottom line is that there is no perfect temperature for any engine. An engine should be tuned for optimum performance, not for a given temperature range. While in this "sweet spot," a temperature gauge is used to measure engine temperature. Take the temperature readings from several points around the head to get an average, but most important is around the base of the glow plug, where the main combustion occurs. Using this temperature as a benchmark, frequent temp checks on subsequent runs will tell you if your engine is running too hot or can be leaned out a bit for more performance if it's running too cool.

While the effective operating temp for any engine is unique, a general rule of thumb for any engine is between 210° and 260° with some modified high performance engines approaching 300° Most .12 and .15 engines will come in around 220° to 240°. This is not a hard-set rule.

Without benefit of a temp gauge, a general state of the engine's temp can be gleaned from a dime-sized drop of water dropped on the engine head, also known as the "spit test" for obvious reasons. Water boils at 212° fahrenheit. If the drop of water boils slightly and evaporates in 5-10 seconds, the engine is probably in a safe range. If is sizzles and pops like a fried egg and the water never really settles on the head, chances are you are running too hot and your engine is screaming for help. Enrich the mixture to bring the temperature down.

Fortunately most engines will stall or burn out a glow plug if they overheat, but this doesn't mean you're not damaging the internals. It just means you get another chance. Extreme overheat conditions result in engine siezure or a broken connecting rod, known as a blown engine in the radio controlled hobby.