I have searched the net for information, but to me it seems somewhat different depending who I ask. My question is if i have a glowplug that works fine in summer (20-25 degrees centigrade), but during cold days (0 to minus 5 degrees) my engine wont start. Should i select a hotter glowplug or colder?

Rgrds

H

I doubt that the glow plug heat range is the problem. The heat range of the plug effects the engine timing a bit but shouldn't have any effect on starting. It could be that the glow plug has gone bad. Try a new one of the same type. It may be the battery in the igniter which can't put out much current at such low temperatures. Be sure it's fully charged and keep it in your pocket to keep it warm until you attach it for starting. If you have a power panel, use the glow plug connection with an appropriate plug connector instead of an igniter. If you still have starting problems, you might try priming with a little ether at the carburetor. This can be done using a squirt bottle (starting fluid with ether is available at wal-mart and auto parts stores).

Hi and thanks for your answer. Probably i was a little bit unclear in my earlier message. The problem is that the engine dont run well when its cold outside. I can get it to ignite (without problems) but i cannot get it to run for longer periods than about 20 seconds. As soon as i increase or decrese the throttle the engine dies. So to summarize, i have serious problems to make my engine run reliable when its cold. During summer this is no problem and the engine runs as a dream..

H

The OS type F plug is pretty hot , but I dont think that is your problem. I would guess you are running a low or
no nitro fuel. At that cold of a temp you may have to leave the ignitor on until the engine warms up.
At 32 degrees F which is 0 on Cel. I have to leave the hot shot on my ST .90 about 45 seconds. The engine
has to be warm to the touch or it will die if the throttle is advanced. You can also pre warm the engine a little.
Use a lighter or hot water from a thermos around the cylinder head to pre-heat. later daveo

You didn't say if you adjusted the needle valve. The colder air is more dense, but the carburetor meters fuel by volume, so that as the temperature goes down, the mixture (which is mass ratio) gets leaner. It sounds like it's a little too lean. Try richening it up to start it then adjust it (lean it) to peak and back off a little.

Thanks for your answers guys, really appreciated..
I have tried to change the mixture, but the same symptoms was observated (until i changed it too much so the engine was "drowned"). Im desperate.. I think i have tried almost everything, so my last hope now stand to the glowplug. Going to try this with hotter plug in the weekend, and reporting back here how everything went.

H

Clarence Lee, our engine guru, suggests more nitro or adding 3% gasoline to the fuel. You can also wrap the cylinder in alum foil to help increase the heat.

RCPAUL

I can run my fox 40 at -15 c with out any problems ,just a little hard to start and have to keep glow on it for a while . You did not say what engine you have some just do not like the cold .
Ron

Just a thought

Up here in ND it gets pretty cold too, You might want to wrap a rubber band around the head to keep the heat in . I haven't tried it but have heard guys in the club mention it when they fly off of the ice at the lake.[img]i/expressions/face-icon-small-wink.gif[/img]

I'll tell you what...I live in northern minnesota and it is below the freezing mark every day, alot of the time below zero. I have two motors that do this same thing. In the heated garage, the engines will run great, with an os 8 glowplugg and 15% nitro fuel. Outside, in the cold. I have to use 30% heli fuel along with the same plugg. I was told by the techs at horizon, ( you have to make sure the head stays at a certain temp, or the motor WILL die.) I do most of my flying in the winter and can assure you, this approach works.

Hi all and thanks for the good replies on my question.
I tried some different ways of solving this problem and
the solution that works best for me is the following:

I bought a slightly hotter plug, this advances the ignition
point slightly, however by increasing the needle mixture
the engine gets more fuel. More fuel cools the engine which
delays the ignition point. These two factors takes out eachother
so the hotter glowplug makes my
engine run on a richer mixture at the same ignitionpoint.
And now it runs perfect even under very cold conditions.

Thanks all!