1998 Mercury 9.9/15HP 4-stroke outboards factory service manual, Page 23Get this manual
MAINTENANCE
Storage Preparation
The major consideration in preparing your outboard for storage is to protect it from rust, corrosion, and damage caused by freezing of trapped waterThe following storage procedures should be followed to prepare your outboard for out-ofseason storage or prolonged storage (two months or longer)
CAUTION
Never start or run your outboard (even momentarily) without water circulating through the cooling water intake in the gear case to prevent damage to the water pump (running dry) or overheating of the engine