I have an OS 46AX and this morning when I took it for flying, the shaft wouldn't turn over. Undoing the spinner revealed the engine is locked up.

Typically, it takes about 40 seconds for the pump to fill the tank, today it took about 10 seconds. Could this be an indication that the engine is flooded? The fuel tank was full, but this could also be because I might have not defuelled last time;

Also on my first crash, I had to undo the muffler to remove the engine, that is when I noticed (although cannot clearly remember), I could see the piston moving at that time, but this time when I took off the muffler, nothing was moving. Everything seems jammed...

So i am kinda confused if this is a flood lock or a piston/crank seizure.

Any help/steps to diagnose is appreciated.
Many thanks
GS

UPDATE:
I took off the glow plug to see if there was any fuel logging. The cylinder looks clear, but the piston is jammed, does not move up or down when I rotate the prop by hand. Also, there is a metal hitting sound at the extremes of the ~290 degrees of totally free propeller movement.

I tried pushing down the piston with a piece of clean balsa wood and very little force, but it wont budge... Still looking forward to suggestions...

cl me  09021109685..there is posting issue..trying ,bt seems smthng prob.

If there are metal sounds, then something must be broken/dislodged inside. Looks like it is time to disassemble and check.

http://www.rcindia.org/fuel-and-engines/nitro-engine-maintenance-videos/

Thanks Arvind and Anwar,
After talking to Arvind, seeing the videos, and reconsidering the symptoms, quite sure it's the connecting rod that's broken, but will have it opened up and update.

Many thanks both
GS

thrice in 6 days... i am hearing of an OS connecting rod failure.....

must say... OS quality is going down.....

I recently talked to the India dealer of O.S mentioned on the website, and he did mention that many parts of the O.S are being manufactured in HK. He also did mention that most of the carbs on the newer O.S engines are aftermarket ones from HK being fitted on the engines. I don't know how much of that is valid or any signs to look for but what I am sure of is that in my engine, the con rod is broken, had crank cover opened and there lies the con road broken alongwith the inner sleeve.

Time to fish for a new con rod

GS

For the case of OS, the spares are bit costlier but one can get them.it is unlikely that connecting rod broke.

I too heard and noticed lately that the newer OS engines are manufactured in China.

Thanks Sandeep,

I wanted to get my hands dirty with oil but the last time I opened up an engine was of my Enfield years ago with dad; This being a much smaller machine, did not want a spring popping up or something similar which would take a while to figure out where to fit, and am quite sure would not have been able to commit the changes anytime soon so I contacted Mr. Kalsi for replacing the control rod. His resourcefulness will undoubtedly ensure I get that connecting rod placed and working well.

Now that I have examined and am acquainted with the guts of the engine, I am hoping it will be easier if anything like this recurs. Did not fly this weekend and cannot afford to missing flying next weekend as well

Thanks again all.
GS

Update:
The connecting rod has been replaced and after two tanks of running-in on ground, I flew the boomerang this Sunday. All seems to be working well. I've now dozed in some WD40 before running.

I have no idea why the piston got stuck in the cylinder, a mallet head and some heat was required to bring the piston out; probably the cylinder cooled down and grabbed onto the piston. There were no scratches on the piston but the connecting rod gave way on the other side as well while pulling the piston out.

Attached is a pic of the broken connecting rod. This goes in my memorabilia

Thanks all for all the help extended