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Lost Oracle · 03-14-2014, 12:34 AM

Hello everyone,

Lately my os engine had been heating up throughout the flight without any obvious reason. The smoke is thick indicating a rich condition. The most peculiar part is that the temperature rises very quickly after the motor shuts off and will drain what's remaining in the fuel tank and drip out the backplate. I have a temperature telemetry sensor installed so I have a pretty good idea of what the temp is doing throughout the flight and it really only becomes a problem halfway through a flight. Today the engine quit midflight and after quitting the temp went off the charts.

Anyone know what I might be experiencing.

Thanks,

Mike

DCflyer · 03-14-2014, 09:25 AM

Any time there is a it change in lean/rich mix and nothing has changed on the heli or the weather it's most likely your glow plug. I change them every couple of gallons

marc8090 · 03-14-2014, 09:52 AM

Couple things: I have never bothered to check temps after stopping the engine but I can tell you that engine temps will go up on a liquid cooled engine after shutdown because you are no longer circulating fluid. Could be the same way here since there is no longer air being blown over the head and also no longer fuel being run through the engine to help cool it. As far as the engine emptying the tank after shutdown, that indicates the regulator is stuck. The fuel is probably pouring out the carb opening and looking like it is coming from the backplate. You should be able to leave the tank pressurized after shutdown and it should not empty or flood the engine. Now, if you manage to get the regulator working correctly, and the engine is tuned well, and it still overheats part way through a flight, I would look at your clunk line. Possibly once the fuel gets below a certain level you are sucking air and running lean. A way you could test this is to only fly the top 1/3 of the tank, before the point where it leans out. Fill it back up and keep repeating. If it runs correctly, the overheat is occurring at a certain fuel level, not after a certain amount of time.

meowguy · 03-15-2014, 06:34 AM

My engines are running at about 150 to185 deg. F in the summer. You should be able to touch the back plate without wanting to pull your finger away quickly. My telemetry sensor is around the base of the cylinder just above the crank case.

I am not sure what the condition of the glow plug has to do with how hot the engine runs and I don't change them every gallon of fuel. Someone would have to explain the physics of that to me. I change glow plugs usually as a trouble shooting technique of last resort that has rarely worked to solve an engine problem (or once a year whichever comes first). It is almost always a fuel or fuel delivery problem that causes poor performance. That would have nothing to do with your problem unless you really are running lean. I use 15% nitro.Omega Heli, about four gallons a year between my OS .50 and .91.

I hope this helps. Jim.

03-14-2014, 12:34 AM	#1 (permalink)
Lost Oracle Registered Users Join Date: May 2011	OS .91 HZ-R Heating Problem Hello everyone, Lately my os engine had been heating up throughout the flight without any obvious reason. The smoke is thick indicating a rich condition. The most peculiar part is that the temperature rises very quickly after the motor shuts off and will drain what's remaining in the fuel tank and drip out the backplate. I have a temperature telemetry sensor installed so I have a pretty good idea of what the temp is doing throughout the flight and it really only becomes a problem halfway through a flight. Today the engine quit midflight and after quitting the temp went off the charts. Anyone know what I might be experiencing. Thanks, Mike

03-14-2014, 09:25 AM	#2 (permalink)
DCflyer Registered Users Join Date: Jan 2013 Location: DC	Any time there is a it change in lean/rich mix and nothing has changed on the heli or the weather it's most likely your glow plug. I change them every couple of gallons __________________ OXY5 MEG / 12S RAW KSE / 14S TDSF / 6S OXY rep

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03-14-2014, 09:52 AM	#3 (permalink)
marc8090 Registered Users Join Date: Sep 2006	Couple things: I have never bothered to check temps after stopping the engine but I can tell you that engine temps will go up on a liquid cooled engine after shutdown because you are no longer circulating fluid. Could be the same way here since there is no longer air being blown over the head and also no longer fuel being run through the engine to help cool it. As far as the engine emptying the tank after shutdown, that indicates the regulator is stuck. The fuel is probably pouring out the carb opening and looking like it is coming from the backplate. You should be able to leave the tank pressurized after shutdown and it should not empty or flood the engine. Now, if you manage to get the regulator working correctly, and the engine is tuned well, and it still overheats part way through a flight, I would look at your clunk line. Possibly once the fuel gets below a certain level you are sucking air and running lean. A way you could test this is to only fly the top 1/3 of the tank, before the point where it leans out. Fill it back up and keep repeating. If it runs correctly, the overheat is occurring at a certain fuel level, not after a certain amount of time.

03-15-2014, 06:34 AM	#4 (permalink)
meowguy Registered Users Join Date: Feb 2012	My engines are running at about 150 to185 deg. F in the summer. You should be able to touch the back plate without wanting to pull your finger away quickly. My telemetry sensor is around the base of the cylinder just above the crank case. I am not sure what the condition of the glow plug has to do with how hot the engine runs and I don't change them every gallon of fuel. Someone would have to explain the physics of that to me. I change glow plugs usually as a trouble shooting technique of last resort that has rarely worked to solve an engine problem (or once a year whichever comes first). It is almost always a fuel or fuel delivery problem that causes poor performance. That would have nothing to do with your problem unless you really are running lean. I use 15% nitro.Omega Heli, about four gallons a year between my OS .50 and .91. I hope this helps. Jim.

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