I screwed up something
 

Hey I have an Alpha 40 trainer and last night I had a ton of trouble trying to start it. I primed the engine and did everything by the book, then I took the electric starter and went to start it, but instead nitro started shooting out of the carburetor and my propeller spun right off. My plane has been started before by and instructor at the field, so I know it works. Also, I changed the glow plug so I know that is good as well. Any help?

RE: I screwed up something
 

It sounds like the engine was "hydro-locked". That is, the cylinder was so full of fuel that the starter couldn't turn it. I doubt you hurt the engine if you stopped using the starter quickly. However, I have seen connecting rods bent by this problem.

When you prime your engine, turn it over one or two revolutions by hand after you prime it to make sure the cylinder isn't full of fuel. NEVER use the starter to prime it. It usually doesn't take much priming to get the engine going. Maybe 3-5 turns with the engine at full throttle and your finger over the carb barrel. With the glow lighter OFF, of course.

Dr.1

RE: I screwed up something
 

dr1driver is correct.I usually teach my students to turn the prop through until they see fuel at the carb then 1 more turn close throttle. Sounds like you primed way too much.
The prop came off cause it was hydro-locked.
Why were you trying to start it anyway? I hope it wasnt to fly without an instructor.

RE: I screwed up something
 

I wasn't planning on flying it but I do have a big back yard and I wanted to taxi it a bit. I am in a club and had my instructor start it once and trim the engine. I watched him do it and followed his instruction, I guess I just overprimed it. Thanks for your help. Is there anything I need to do to "unhydro-lock" it? or will letting it sit for the night be fine?

RE: I screwed up something
 

Remove the glowplug, and turn the engine over with your electric starter. Watch yer face, there'll likely be alot of spray from the plughole. When Ol' Faithful subsides, reinstall the plug, do not prime, and start the engine.

Be careful not to become airborn by mistake! Watch your fingers!

RE: I screwed up something
 

Put a rag or paper towel over the plug hole while "motoring" the engine over to clear it. Also make sure you don't lose the plug washer.

Be sure to tighten the prop tightly.

RE: I screwed up something
 

Did your instructor suggest this? I wouldn't do it, at your level. all it takes is abit of speed a bump in the grass, a tad bit of head wind or a twitch in the throttle thumb and you could be airborne.
after my students get their turns down pat I'll take 'em to the end of the runway and pratice taxiing away from themselves and then toward themselves, at the time we had grass runway. takes more power to begin to move than to keep moving.
anyway all of a sudden my students airplane is under too much power, I ask her to back off the throttle she says she cant and hands me the transmitter. no throttle response all I could do was wait for the airspeed to build and fly.
throttle servo stripped.
It's your plane but I'd wait

RE: I screwed up something
 

Leave the wing off. Won't fly far that way.:D KEEP THE SPEED REAL SLOW. Oh, and stuff a rag or old T-shirt in the wing opening if you think fuel residue will get inside the fuselage.

RE: I screwed up something
 

i was having a hard time starting up an older glow engine couple days ago.. didnt have a specific primer, but i know to hold the exaust shut and that usually primes it.. well.. i know what im doing with these thigns and i know eveything is in place but it wouldnt turn over, i checkd the head and it was dry... they, i had a friend turn it over while i very lightly blew into the air hose from the tank... that primed it perfect.. the engine has the ability now to suck as much fuel as it can handle because without priming it you make it readily available.. so, now i have a little setup where i just put it at the end of the air hose form the fuel tank, put litle pressure (kinda like a ballon) and in no time, no struggle.. starts off fine..

just thought to share.. maybe some of you knew this allready..

RE: I screwed up something
 

Is it possible to prime an engine by putting a drop or two of fuel into the carb using a dropper?

RE: I screwed up something
 

Yes, but don't overdo it.