Originally Posted by ruddles
Hello gurus and fellow boaters
Is there a SAFE way to flush an outboard with fresh water when it is NOT running ?
It's not a safty matter issue, that is, with engine off the thermostat will never open, won't have a well flushed cylinder head, with engine on you'll have. Very small portable engines that doesn't have a thermostat can be flushed with on/off engine as water will freely circulate inside engine.
If you are reffering to your Toh 18 engine, side to the leg add oil screw, there is a flush screw, get yourself a Toh flushing adapter, code 336-6000-0, remove water screw, finger tight adapter, connect a water hose, turn water on, start engine and flush for about 5 minutes, let time for the thermostat to open and wash cylinder head properly. Find this method to clean better than muffs or barrel as having a better pressure/flow through engine.
There are some issues, must duct tape both water intakes and under anticav plate small water intake to close them or water will exit through them lowering water pressure inside engine. As having already a heavy duty muffs set, have just to tape the under anticav intake. If using adapter, place a screw clamp on hose to prevent from getting off the adapter because of water pressure. Don't forget to remove all 3 tapes from leg when finished or will ruin your engine in your next outting with a severe engine overheat.
The flush adapter has a wide intake, but a narrow exit, so no pressure probs inside the engine, will lubricate impeller well, having a controlled water flow through the entire engine, besides it's factory recommended along with muffs or barrel cleaning. Up to you which flushing method suits you best.