[thstone]

A spare engine should be prepped for long term storage just like you'd prep the engine in your car for long term storage. Do a search and you'll find lots of advice. Additionally, you need to keep ALL of the critters out as they can do a lot of damage - be sure to seal off all of the engine access points (intake/exhaust/hoses/lines/etc). The less temp and humidity changes, the better (enclosed storage is better than outside, heated is better than non-heated, etc). Sounds like you'll need to do a clean up, full prep, and re-package this fall.