Engine sitting for 15 years, what do I do?

[squirrelslayer777]

I'm new to engines and boating in general. I am going to introduce myself to this world by getting a boat fixed up that has been sitting outside underneath a tarp that has mostly rotted away for 15 years. I'm not really sure where to start, I figured that I would try changing the oil and putting new gas in her and seeing what happens. I don't even know where to look for the serial number to see about buying a manual. Any advice would be greatly appreciated.

It's a Merc 350 35 HP twin

 

[gm280]

With most any engine that has set that long, you should check all the fuel lines, They are probably rotted and need replaced. I would pull the plugs and clean them for the initial trial run and then replace them with new. Check the lower foot section for oil and if it looks clean and not milky or has any water coming out, if it looks good, I'd drain it and put new oil in. Next I would do a compression test with the plugs out to see what the compression is. That will tell you if it could run. Then if all that looks good, I would remove the carb and install a carb kit after a good cleaning and replace it back. I would also replace the water impellor as well because it is probably shot too. Then I would mix up some 50:1 fuel oil mixture and see if it will crank. Could even spray a little 50:1 mixture in each cylinder so it has some lube when trying to start it. But only try to start it after doing all those checks to make sure everything is good... JMHO!

 

[BigSkyMercGuy]

There'd be no oil to change; it was in the gas. New battery, of course. My guess would be the carb is packed with varnish from dried gasoline. I imagine you'll be soaking it and running wires through the tiny orifices you'll find. Maybe while you're doing a compression test, check each removed plug for a spark. Looks like a great project; have a blast!

 

[gm280]

There'd be no oil to change; it was in the gas. New battery, of course. My guess would be the carb is packed with varnish from dried gasoline. I imagine you'll be soaking it and running wires through the tiny orifices you'll find. Maybe while you're doing a compression test, check each removed plug for a spark. Looks like a great project; have a blast!

The oil I am talking about is the lower foot oil and he needs to see if there is any and what it looks like before trying to start the engine. If the lower foot section has water mixed in with it, there will be rust for sure and you don't want to try and run it with such conditions...