OS Max 37 sz Hring won't start - RC Groups
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Mar 21, 2010, 06:34 AM
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OS Max 37 sz Hring won't start


Tried to start this engine, fitted to a helicopter, today. I bought it new last year. It was broken in, and used on the chopper a couple of times last Spring.

Trying to start it today and when I attach it up to the starter, it can barely turn the engine over - seems very stiff. Any ideas?
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Mar 21, 2010, 07:58 AM
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Hemikiller's Avatar
The fuel and any castor oil in the engine is probably all gummed up, or your bearings are rusted badly. There's three ways I know of to free a gummed engine: heat, fuel or dis-assembly. You can try a heat gun on the sides of the engine, being careful to not to damage any of the plastic parts.

If that does not do the trick, then flood the engine with fuel. Remove the glow plug, rotate the crank so the piston is at bottom dead center. Use your fuel pump and literally fill the engine with fuel. Let it sit for a while, rocking the crank back and forth to work the fuel through the engine. When it's sufficiently free, pour the excess fuel out of the cylinder and muffler. With the glow plug still out, gently tap it with your starter, which will blow out the excess fuel. You might need to repeat this a couple times.

If fuel flooding does not do the job, you are probably in need of a set of bearings, so it'll have to come apart. If you pull the backplate, You should be able to see what's going on inside.
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Mar 21, 2010, 06:17 PM
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remove the glow plug and see if that has thick goo on it then feel how stiff the engine is without the glow plug.
Also check if the carb barrel mooves freely or you could overload your trottle servo.
Mar 22, 2010, 07:45 AM
Registered User
Hello all,

Removed the glow plug, it is clean. Engine equally difficult to turn over with it removed. Carb barrel moves OK.

I will take the engine out next weekend and see if I can find a problem - in the mean time, my starter has stopped working - left it connected to the car battery while I wrote the above post and by time I got back it had stopped working - it was hot, but did not smell, so not sure what the problem is. Maybe it's just the starter that wasn't working properley. Will get a new one and see.
Last edited by jonotaylor; Mar 22, 2010 at 08:24 AM. Reason: typos

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