Hydrolock - newbie fail
Was all set to launch last week up in Oban, fitted a pair of Beachmaster removeable transom wheels to my Honwave T38IE. Inflated it on the slip way nose down, lifted the rear wheels and lifted my Yamaha F15 outboard on. All looking good, I nipped up with my girlfriend to get changed in the dive centre only to return 5 mins later to find the whole boat full of engine oil!. I cleared it up with an old rag and continued the launch thinking there wasn't that much oil spilled from the leak.
lowered the engine into the water, primed the bulb and went to give it a pull start.....SOLID, wouldn't budge! check neutral selection and tried again...totally locked, the pull cord moved about an inch. I removed the cover and checked the gear lock mechanism, manually opened it so I knew it should pull...again solid, no movement and locked again. Eventually after some time of checkin things we gave up and packed it all up.
After some research the symptoms were identical to a hydrolock, in my case oil (not water) had filled the cylinder head and created a block. the fix was easy. take out the plugs, and do a few pulls to clear the oil. I did this and it splatted out loads of oil all over the boot of my car!!! (note to self - always target the engine away from the car next time)
wiped up loads of oil draining out, refitted spark plugs and at least it turned over now but no life. Considered the carb next. opened the drain screw to see loads of oil flooding out, so let it drain completely then pumped some fresh fuel through. Cleaned the plugs again and tried again. Eventually a bit of life returned to the engine and it started in a haze of blue smoke (oil burn). I let it run in an bucket of water for about 30 mins until it was running smooth and clean again.
Morale of this story - never let you engine bottom raise up higher than the cylinder head or you'll incur the same issue.
same process applies for a water hydrolock, but you need to flush out any salt water really quickly before it starts to corrode things. this can start in mins of removing it from salt water, so its best to have it submerged until ready to flush and lube.
next time I hope to have a less stressful launch.