Honda GCV 160 lawnmower possibly seized engine.

[Mick-hdh]

I have inherited a Honda GCV 160 lawnmower that was in excellent condition and working last year and then inadvertently stored almost upright and leaning forward, mot by me I hasten to add.
On Sunday I stood it down and left it for an hour, hoping to let any liquids settle. I then checked oil and petrol levels, oil was surprisingly at correct level. The mower started ok but after around 1 minute of running, started to billow thick blue smoke from the exhaust before stopping. It had spewed black oil from exhaust onto the surrounding silver 'skirt' and engine appeared to be seized as I was unable to pull the starting rope to turn over the engine. After leaving for an hour, it appears that I can, pull the rope and although this indicates the piston might not be seized into the cylinder, it does feel quite restricted. The engine oil level doesn't appear to have dropped which is confusing.
Any helpful comments greatly appreciated. I'm quite happy to strip it down and investigate.
Thanks in anticipation.

 

[ILENGINE]

I would start by removing the spark plug and cranking the engine to see what comes out of the spark plug hole. And then check/replace the air filter if it is oil soaked. Honda air filters don't like getting wet. Doesn't matter if by gas, oil, water, they basically will permanently clog the filter.

 

[Mick-hdh]

Thanks for the advice, I will check that. I only get to the piece of land at weekends.

 

[frenchriverco]

It sounds like the oil had seeped above the rings and into the combustion chamber. While most of the fluid returned to the crankcase, as it indicated the correct level, there's a chance that some remained above the rings. This would cause the smoke once the engine was warm. As that oil burns, it's possible that it is "carbonizing" the cylinder wall. This would cause restriction on the stroke and provide resistance to it turning over. I would suggest removing the spark plug and using a borescope to inspect the cylinder walls. If you don't have one, you can always opt for removing the cylinder head for a visual inspection. If that is indeed the case, simply flush the cylinder walls and rehone.