[AlexR]

I've got a second hand Yamaha 9.9 2 stroke (5 years old). Engine runs fine but doesn't have a stream of water coming out of the pee hole/telltale. Instead it breathes out a very fine mist of water. Is this normal? How can I tell whether the cooling system is working ok or not?If it is not normal, how can I tell whether any damage has been done to the cylinder/pistons or not?

[Waterbugtoo]

A fine mist is normal out the exhaust relief. Check the pee hole to make sure its not clogged up. Us a stiff wire to clean it out. Check compression for condition of internals.

[rons boat]

Feel the head with the engine running and notice if it gets hot to the touch. Those pee holes are home to a lot of spiders. Use a small flexible wire with the engine running to see if you can break up a possible obstruction. Sometimes I use a hay wire hose conversion connected to a garden hose and force water backwards. Rarely on a properly maintained motor is there a thermostat problem. Oh, how long has it been since impeller was changed?