Hot engine
 

I have an O.S. .40 LA engine; I recently put it on a test stand to run it and check it out. After I was done I was surprised at how hot the engine was. I've never seen this before, but I am new to the sport. Anyway, the only things that weren't hot were the prop, the remote needle valve and the throttle arm. Even the spinner was hot. I coudln't touch the carb. either. All my other engines are all BB and are the newer style engines with the tri-metal and none of them get this hot. I even have an old Magnum XL BB engine and it runs like an ice cube compared to the LA. I'm running Power Master 15% in my engines. Isn't the LA a bushing engine? Is this typical? I'm all ears; educate me please.

RE: Hot engine
 

The LA is indeed, a bushing engine. Bronze sleeve. Two typical reasons for an engine to run excessively hot are too lean and/or too much (diameter) prop. It needs to break in a little, too. Run it on the "wet" side of lean and use a smallish (10-4, 9.5-6) prop for the first few tanks. ABC/N engine - use fuel with synthetic oil or a syn/castor mix. Around 10%-15% nitro.

RE: Hot engine
 

Check the manual for type of glow plug, propeller size and castor oil minimum content:

http://manuals.hobbico.com/osm/40-46-65la-manual.pdf

Although the one you use is just fine, avoid any synthetic oil-only fuel for this engine.

RE: Hot engine
 

Major brain fart here. You are correct. Syn/castor blend is the fuel to use in an ABC/N engine. My mistake and my apologies.

RE: Hot engine
 

also remember that while running engines on the test stands or planes that are tied down, they wont get enough airflow over the engine to cool them compaired to in the air...... so always run them only for short times and keep an eye on the temps.



bass

RE: Hot engine
 

Don't assume that it's too hot. Yeah, they all get very hot. You'll burn your hand if you touch it just about anywhere.

All the advice about how to deal with a too hot engine is good. Excellent as a matter of fact. But if you're new as you say you are, there is a fair probability your engine wasn't too hot. If it had been, it probably would not have run very long.

The best way to tell is to look at the exhaust. If there is some "smoke", your needle valve is set rich enough. The smoke actually is excess, unburned fuel (mostly oil) that is supposed to be taking heat out of the engine so it doesn't get too hot. If you don't see any at all, richen up the needle setting or you will see the results of too hot running and THEN you will need all the advice given so far.

RE: Hot engine
 

An engine shouldn't transmit much (if any) heat through to the crankshaft and especially all the way to a spinner. Given that your engine has a bushed crankshaft there are two possibilities I can think of. One is that your fuel doesn't have enough oil in it (and castor is preferred for bushed engines at about 20%). This might be because of the blend or a bad batch (it's happened!). The other possibility is that your engine has a particularly tight fit between the crankshaft and the bush or there's no free play in the crankshaft. You should be able to push the crankshaft in and out very slightly, sliding it in the bush. Whenever I start a new bushed engine I always put a finger under the crankcase below the carb to check that it stays cool.

RE: Hot engine
 

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Check that part #9 shown in the exploded view on page 30 of the manual is properly installed. (Link in Post #3 above).