engines sieze from sitting ,Why?

[mike1969]

I have a few questions about what makes an engine seize when setting for a long time.

I watched a re-run of American Pickers and they bought 2 old engines that had been sitting in dirt in drafty old sheds for many many years. One was an Indian engine from the teens and another a Curtis from the very early 1900's and neither were seized.

Honda engines seem to seize after a few years of dis-use. I don't have any experience with any other bikes,is this common with other brands also?

Is it the material the engines are made of or old fuel sitting in the engine or environment?

[cyclon36]

There are a lot of variables that play into this. The biggest contributor is moisture. Southeastern states are the worst on bikes while northern and western states a bit easer due to lower humidity.

Also, it depends on where the valves stopped when parked. If valves on both cylinders were open, that increases the chance of moisture getting into the combustion chamber. It's often exaggerated when the exhaust is missing and the exhaust valve is open or vice versa with the the air/fuel side.

Other things such as the bike running low on oil before it was parked, not being covered, or left outside add to it as well.

I'm not sure how much this has to do with it, but I would assume that newer bikes also had a better seal between piston and cylinder wall. This would cause even the slightest rust or debris buildup to lock the piston in place while older engines with more blow by issues would have a better chance of breaking free.

[mike1969]

Thanks,that's helpful.

Do very dry states like Arizona have engines seize from sitting?

[bonjour]

If an engine has been sitting for 10+ years and nodoby ever gave it a 'kick over' in the meantime , just count on it it's stuck. ( can't go wrong that way )

If it's not, youre lucky.

I think there is no telling, not a single engine is the same, every day conditions are different, etc.

[Snakeoil]

It does not take much for an engine to stick from rust. When I was a kid, I rode a dirtbike in the rain with the air filter off until it quit. I had to push it home. I was pissed (and dumb) so I closed the garage door and never touched it for a week. I was grumbling to my father about it about a week or two later and he went out and the bike was frozen solid. He pulled the head, squirted some liquid wrench inside, and tapped on the piston with a baseball bat until if finally broke loose.

I pulled an engine apart that sat outside for years, buried in the snow every winter, while the owner sat in jail. One piston was seized fast from rust and the other was like new. My only guess was angle of the bike allowed water to get in thru carb or exhaust and rusted the one jug over time.

I know guys who have pulled tractors out of barns that sat there for many years and when given new fuel and battery, fire right up.

I think it is a combination of aluminum pistons and moisture that kills any engine that was not seized before it was put away. An open exhaust or intake valve lets moist air in to condense. Missing spark plug funnels water in for bike left outdoors. The variables are many.

Those old engines that the pickers find may very well not have any pistons in them. I've seen more than one engine that was assembled with parts missing for unknown reasons. Once was given a 1949 outboard that was like new, with zero compression. Took it apart to find no rings. Only thing wrong with it was gummed up carb. I suspect the owner knew nothing about engines and rather than clean the carb first, pulled the engine apart when it would not start and could not get it back together with the rings installed.

regards,
Rob

[mike1969]

Great info!,Thanks.

I hadn't thought of those old engines not having pistons or rings! Guess those shows don't give you the full story about the actual condition of the engines.

My uncle told about about an old car he bought in the 50's that had a bad miss. After checking everything he could think of he ended up pulling the cylinder head. There was a wooden plug in place of the piston and connecting rod!

[rustywrench]

My uncle told about about an old car he bought in the 50's that had a bad miss. After checking everything he could think of he ended up pulling the cylinder head. There was a wooden plug in place of the piston and connecting rod!

My dad told me a story about doing that very thing to an old plymouth he had to get running out of desperation, HMMMMMMMMMMMMMM, I wonder,,,,,,,,,,,,,Rusty