Ok, I thought I bent my crank but here 's the deal. Without the glowplug in the engine turns over very smoothly. It has about 20 runs on it and is 2 months old. It ran purfectly until the other day. Now when the glowplug is in, I can't get it to turn over with my starter. By hand it turns over but I can't get it to start. With the glow plug out it turns over without a problem. I have drained all the fuel and blown it out with air. I have removed the carb and cleaned it. I don't know what to do next. HELP!!!!!

Charge the starter battery?

Also check to see if it is flooded. Just before trying to start, remove the glow plug and hit it with the starter to blow out any fuel. Then replace the glow plug and try again.

What size is the engine? If it is a smaller engine it may not like a long glow plug. If it is 40 size or similar then it should be fine.

Good idea to take a look at the plug too and make sure it glows when you put the juice to it.

If your at the field and it wont turn over, try setting the engine near the exhuast of your vehicle, and letting it "warm up".

Its an OS 46FX,

The Starter battery is charged

The glow plug does work, and it doesn't matter which one I put in, It still won't turn over

I have taken the plug out and turned it over with the starter up right and upside down, I've blown it out with air, I've taken the carb off and blown out the crank casing and the carb itself. I've removed the needle valve and blown that out

It won't start inside either after sitting there for a day so warmth is not an issue.

Ya got a washer under the plug?

Let's recap; It will turn over by hand with the glow plug in, just not with the starter. Correct? If so, I'm assuming that the piston is not bumping the bottom of the glow plug.
First, from what you've said, I don't think it'll have anything to do with the carb or the needle valve or trash in the line or anything of that nature. Besides, the only possible relationship that could exist there is if you're flooding it and you've already said that you cleared it by removing the glow plug and spinning the fuel out of it right? It's normal for the engine to be much harder to turn over with the glow plug in place. With it removed, there's no compression so naturally, it's easier to turn.

Questions- Do you have any experience with hand starting? If you can get it started by hand then you can verify that the engine itself doesn't have a problem.
Have you checked the voltage on your starter battery? Is the starter cone just spinning on the spinner or is it coming to a stop, unable to turn the motor past compression?

Just trying to ask enough questions to give us all some clues as to what the trouble is.

Does it turn over with the starter when the plug out? Does it blow fuel everywhere? You may be flooding it? Also make sure the plug is not hitting the piston like previously said. Is there anyone flying close to you that knows engines that can help you?
Maybe have them take a look.

Mr. Reid

Thanks for the reply for starters
OK, It will turn over by hand and with the starter I can get 5 to 10 turns If I'm lucky, 1 or 2 average. I don't believe the plug is bumping the piston because this engine ran very well for about 20 flights and then just one day, I was faced with this, and I have tried smaller plugs as well, same result.
Yes the fuel is all out.
Yes, I have some experiance with hand starting however It just doesn't want to go
Voltage on the starter battery is full. I can start my other engines no problem and I recharged it the other night just to make sure.
The cone is not spinning. It comes to a complete stop with the prop and is unable to turn the motor past compression. I even tried another starter that my father-in-law has been using for years.

Thanks again for the help, it is appreciated.

Your starter or the leads to it may be bad. If the engine will turn by hand with the plug in it should also turn with the starter.

Does the compression seem right when turning by hand?

Someone has already asked about the washer under the plug (if missing it could hit the top of the piston).

If I read you correctly you said it would turn a few times with the starter and then stop, that sounds as if it is getting flooded.

I have run out of ideas.

My vote is also to check for the washer under the plug.

OK.

Just for grins, try this.

Screw the hi-speed needle all the way in GENTLY on the seat please and leave it there.

Remove the glow plug and turn the engine with the starter to blow out all of the fuel.

Replace the glow plug (leave the needle alone).

Turn the engine with the starter. If it continues to turn then you most definitely have a flooding problem.

If it stops, then you most likely have some other sort of problem UNLESS the carb hi-speed needle is not shutting off the fuel supply for some reason.

Hey, try anything that might give you a clue.

Dan

There is absolutely no fuel in this thing and I have the compression problem. I've narrowed it down past all the fuel problems and I am stuck on this compression thing.
Don't get me wrong, thanks for the replies but it IS NOT A FUEL PROBLEM.

Yes I have made sure it has a washer under it.

As soon as I get the plug in one thread the problem starts. It is hard to turn over at that point. If I turn it down all the way, I really have a tough go.

THERE IS NOTHING WRONG WITH THE STARTER. I have tried two starters and two batteries as stated above, I can start other engines.

Thanks again for the replies. If they don't help now I'm sure they will in the future.

Have you tried backing up the engine all the way against compression, to allow your starter to get a running start? That seems to help me when my engine is being stubborn.

I know this sounds kind of silly, but what prop brand and type are you using? I have an OS 46FX, and when I had a Zinger 10x7 wood prop on it, I had the same issues you are having. I absolutley could not get it to turn over w/ starter, turned over by hand fine. I even tried a 24 volt starter that a guy at the field had, no luck. I think the prop was too light, it didn't provide enough of a flywheel effect to keep the prop spinning. I switched the prop to an APC 10.5x6 and haven't had a problem since. I through away the zinger. I also checked to make sure that there wasn't a flooding problem, there wasn't. So if you are using a lightweight prop, you might want to switch to a heavier APC prop.

Allan

I am not sure about the .46FX series of engines, but I have several smaller engines that I use for combat These engines (Magnum .28XL's) have a sleeve that the piston rides in. The sleeve can fit in the engine in any (rotary) orientation. I suppose it could be possible for the sleeve to have rotated out of position and closed off the exhaust port, causing over-compression.

I would recommend removing the muffler and looking into the exhaust port. While watching turn the engine over slowly by hand (with no glow heat or fuel!) and see if you can observe, through the port, the piston moving up and down. If not, then pull the head and re-orient the sleeve with the ports and slots matched up. If you are not comfortable doing this (don't overtighten the head when re-assembling) then someone from a local club should be happy to help you.

If the sleeve is correctly aligned then try spinning the engine with the starter while the muffler is off. It is also possible that something is stuck in the muffer causing backpressure... it is a stretch, but an easy check to perform and it sound like you have gone through most all the other steps. If the engine spins easily with the starter now, then take the muffler apart and see what is stuck in there.

Hope this helps.

I"m using an APC 10x7 but I'll try a different prop, ya never know.

I'll never thought about the sleeve being out of place I'll give that a try as well.

Thanks for the thoughts. I'll let you know how it goes.

Gladman,

If you know how take the thing apart and inspect it and be done with it. a typical 2 stroke engine has like 10 major parts in it

Inspect the piston remove the sleeve check the bearing connecting rod see if it ingested som foriegn matter.


also take post holes advice about the sleeve moving remove the head the should be a small pin on the cylinder and a notch on the sleeve. Pin goes in notch and sleeve is properly aligned...

I don't mean to nag on the subject, but going back to what dant said about the high end needle. You may not have an issue with fuel/flooding after you blow it out, but it may start to flood after turning it over a few times. I am not an engine "expert" and I am not even sure if it could happen like this, but maybe the needle is set too rich and flooding the engine before it starts. Sorry again to nag about it. It seems to be the only problem I can think of.

That is a good possibility that " Post Hole" has mentioned, I have seen both scenarios in the past. lean ran engines have a habit of expanding more which will allow the liner to rotate, and the baffle disk in some mufflers to to become pinched as the body cools. Some guy's pull the disk and toss it in the drawer.

One other possible cause is a wrist-pin clip has lodged between piston and sleeve, But not likely due to it turning over without plug installed.

Dan Z

just a thought.......when you push your starter against the spinner or prop is the crank sliding back and binding ....
tinker

Well, we did it folks

Post Hole was right. The piston liner had slid to the side and was blocking the muffler. It took two seconds to fix.

I'd just like to take a second to say how much I appreciate you people taking your time and posting replies. These forums are an excellent place for people to gain knowledge and folks such as yourselves make it what it is. Thanks again and happy flying.

You are most welcome, Gladman.

Happy to have helped.

OK, I've held off commenting about this for days now but I'm baffled. It seems the problem was that the liner suddenly rotated inside the crankcase and blocked off the exhaust port? For real?? This should be impossible because for one thing the liner is clamped in place by the cylinder head with 6 screws which means that first all 6 screws have to come loose and then there'd be a complaint about LOST compression! But even then, there's nothing to make the liner rotate because it's only subjected to straight up and down forces. Do these engines use a roll pin to locate the liner? Something just doesn't seem to add up here...but I could be wrong

Vapor lock possibly?