ORIGINAL: rduff55
I have a magnum .15 xls that I have been flynig for about a year I am running a fuel mix of 10%nitro 10% caster and 10% synthetic the engine has been running great until the last few times to the field it has stated eating glow plugs I have richend the highend fuel mix and checked the thead bolts. I can not find any air leaks. I have been running the os hot plug. sometimes I can get a flight and then the plug will be dead when I get ready for another flight some times the plug will go bad after a few seconds of running. any sugestions or ideas would be great.
thanks.
I dont think its rich enough or there are air bubbles going through leaning the mixture. I'd suggest pointing the nose of the plane straight up while tuning the main needle. I pinch the fuel line so I get a slight rise in RPM. If using muffler pressure, I'd also suggest setting the needle at 1/2 tank since the mixture will lean out as the tank runs down. Keep an eye on that fuel line looking for air bubbles. In my experience, air bubbles account for half of the tuning troubles I've ran into.
What do the plug elements look like after they croak? If they're distorted or misshapen, lean mixture is almost guaranteed to be the cause. Just my 2 cents.