I haven't ever flown when the weather was <70 degrees or so. I have a new OS .91 glow 4-stroke, and, before flying season, I decided to break it in. I can't get the thing to start. (I did all the tricks suggested in the engine manual.) The glow plug lights up, and fuel is getting to the cylinder. I've done the usual things--flood the engine, then crank it with the fuel line clamped, etc. It never even coughs.

My problem is that I have two new situations for me: never before used a 4-stroke, and this is the first time I've tried to start an engine when the temperature was in the 40's. I did not try a "hot" plug.


Suggestions? Maybe I'll just wait a couple of weeks until the temperature goes up. Then I'll have just one variable. Or is there something I'm missing with 4-strokes?

Thanks.

In 40's and lower cold, zippo lighter fluid is your friend. Two or three drops in the carb throat does wonders to light off a stuuborn engine. That is assuming all else is correct with your engine.................
Be careful flooding any engine, especially when using a electric starter. I hydro-locked a SF.40 once and bent the rod.

Mike

Are you sure it's not the fuel?

Brand new fuel.

Maybe put in a new glow plug and see if it cranks. Also, be sure you have it set rich enough. If the new glow plug doesn't get it going I would richen the low speed more. I'm not sure if you have already done these things yet so just suggesting here........

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Being brand new, the engine should have come with the proper OS Type-F glow plug. If not, that is one thing that could help the situation.

Lighter fluid works too. I use starter fluid (ether) in a spray can. This stuff does work. Not sure of how good it is for the engine, but I've never bent a connecting rod using it.

I had an Enya 80-4C that was a bear to start in cold weather. The ether worked. Be careful with that stuff, or you'll wind up taking an unexpected nap at the field. <G>


Ed Cregger

Temp. in the 40's is not really "cold"...

Make sure your glow plug battery is fully charged so that the plug (O.S. type F) glows bright yellow-orange, then crank the snot out of it with an electric starter with the throttle set at about 1/4 and if the carb is not badly mis-adjusted it should start.

If that don't do it, check the valve timing...that's about the only other thing I can think of right off hand.

You won't see me at the field these days when it is much lower than 55 degrees. I used to fly down to 25 - 30 degrees (Fahrenheit), but those days are gone.

If it is too cold to ride the motorcycle, it is too cold to fly too. <G>


Ed Cregger

Common problem here in the UK in winter. I use a prime of model diesel fuel. Works like a treat. The ether is the key. If you can't get diesel try mixing equal parts of kerosene ether and caster together and that will do the job.

SOMETIMES i HAVE A QUEUE FOR MY MAGIC SQUEEZY BOTTLE.

Some engines just will not start at low temps due to the low vapour pressure of the active constituent of the fuel. Lighter fuel might work and Diesel engine starter spray defintely will work.

Think I figured it out. I was using an old but previously unused alkaline C-cell for the glow plug. When I tested it before going outside, the plug lit up nicely, and the battery seemed to have a lot of life. After going outside, getting set up, stopping for lunch, etc., the battery must have cooled off sufficiently that there was little juice left. I used another battery from the same package, and--no surprise--no joy.

Tomorrow should be 65 degrees, I'll have a fresh battery as well as a good attitude. I'm sure it'll start.

As a guide--how many amps should the OS type F draw when energized with 1.5 v?

Thanks for all the advice. I have some ether ready in case it remains recalcitrant.

I had a feeling you just might be using a weak plug battery...
A typical glow plug will pull 2-3 amps...maybe a little more? (depends on the plug, and if it's flooded or not, etc.)

You really should get a good Nicad rechargable glow battery, because those dry batteries just don't have the amperage delivery capability, and will croak very quickly...(IMO they're not worth bothering with )

OS F draws about 3A at 1.2V and 3.8A at 1.5V.

Even a good NiMH won't supply enough voltage/current to drive glow plug at those temperatures.

I have always used the alkaline batteries because I figured that 1.5 v was better than 1.2 v. I don't pretend to have tested this, but I guess that the internal resistance of the alkaline battery is enough to reduce the voltage on the glow plug side of the circuit so much that it's less effective. Makes sense to me, but I may try doing the measurements. I have a bunch of NiMH C-cells that I could charge up . . .

Thanks

I'm like ED I used to fly all year long but 40 degrees F is my break off point now days. When I was into control line and starters wasn't heard of we used to put the engines in the flow of the exhaust of a running car or truck to warm them slightly. 40 degrees isn't cold enough that a engine should not start if the batterys and fuel are up to par, remember the cold drains batterys faster that goes for the plane, glow starter and transmitter.

I was thinking the same thing. If the plug is hot and the fuel is good--it's too lean on the low end needle.

Thats a red flag for me. Anytime a new engine won't start, I start looking to see if the low speed needle is too lean.

Close the throttle.
Run the high speed needle all the way in.
Now back it out 3 or 4 turns.
Now run the low speed needle all the way in. Back it out 3 turns.

Try to start it at idle settings. If it won't start--back the low speed needle out 1 full turn. Try again. If it still won't start--back the low speed needle out another turn. You might back the high speed needle out another turn if it still won't start.

If you have the plug lit--and you have air--then all your missing is the fuel. It won't draw fuel if it's too lean, so you gotta open the needles to let it draw fuel.

You hooked the muffler up to the tank and left the bottom nipple on the crankcase alone--right? That bottom nipple on the crankcase is a vent--leave it open--it's not meant to pressurize the tank.

It turns out that the batteries were the culprit. When I bought a pack of new C-cells, the plug stayed lit for a long time. Brighter, too. Cranked the engine again, and it started on the first try. Runs like a top.

Thanks for all the tips. They will come in handy in the future.

BTW--the sound of the 4-stroke is awsome!

RCPilet- I agree. And, you can't always go by a glow plug just because it glows.