Engine knock after shutdown 18hp

Hi all,

im sure someone will know the answer to this one: I just bought a 2007 tohatsu 18 HP. First thing I did was change the plugs and gear oil. I then took it out for a quick test. Started fine ran smooth. Nice under full throttle. As I pulled up to the boat ramp I hit the stop button. As the motor stopped an a second or two after, there was a noticeable knock come from the top of the engine. 3 or 4 knocks. I decided to replicate this and found it changed as follows

1. It would only do it if still in gear and hitting stop button. Wouldn't do it if in neutral
2. It was less noticeable when at idle speed
3. More pronounced if slightly above idle or after just powering down and close to idle speed

help please.....I hope I haven't been sold a problem

What is your actual model? Year is irrelevant. US 18 hp models were phased out by that time. Are you saying the motor made a sound After it stopped running? Could be a loose bolt or maybe a bad motor mount. Never had something quite like that.

Hi Paul,

thanks for posting

im in Australia and its the Japanese model XG

XG is a serial number prefix for 2007 year of manufacture.
Model is in the format M18x or MFS18x.
Can you describe this noise with more detail, including how/when you hear it?
Very possible the prop is ratcheting if you are underway and just kill the motor at speed. Not what we would consider normal operation, but it is normal for that kind of LU.