3.5 Classic engine kickback, but not the flywheel key.

[Abrwstr]

Hi

I have a 3.5 Classic engine on my Alko Tiller, recently had to remove engine (in one piece) from tiller deck to fix and retrieve a broken captive nut in the tiller deck, after job was finished and the engine replaced, I tried to start it but the pullcord snapped back and white smoke came out of exhaust, I tried again with the same result
I assumed that the flywheel key had broken or moved somehow (as it had not hit any object and had been standing for some time), I removed the flywheel and checked but nothin wrong there.
I am now at a loss as to what it might be, any advice would be gratefully received.

Also I have an excellent Quatro engine on a redundant Hayter mower, would the mounting holes on this be the same as on the Classic, in which case I will just swap the engines over and work at leisure on the Classic.

Thanks for reading.

 

[ILENGINE]

Remove the spark plug and then crank the engine a few times and see if oil comes out of the spark plug hole. I suspect that either from how the engine was laid when you were working on the tiller part, or just from setting oil has gotten in the cylinder and is causing a hydrolock effect.

 

[Abrwstr]

Thanks for that Ilengine, I did notice that the plug was a bit oily at the time it happened.
I will definitelty try your suggestion, your advice is much appreciated.

 

[bertsmobile1]

And yes the mounting holes on the classic & quatro should be the same.

 

[Abrwstr]

Thanks for that Bertsmobile, much appriceated.