Impeller failure after blockage

[Petef]

I'm in a Facebook sailing group and this was posted so thought I would share.
Basically his engine raw water inlet got blocked by some plastic. After removing the blockage, his engine was still over heating. An initial visual inspection of his impeller looked ok. But! see pic.
 

[geoff]

On my 40 cc I have had a water flow switch in the raw water supply upstream of the heat exchanger . Any interuption in the flow brings on an alarm . In the past many years it has detected several disruptions including my failure to open the seacock. Cost about £12 from I think RS componants and has proved its worth . Geoff

[IslandAlchemy]

I had an impeller let go like that years ago.

[Craig]

Impellors will lose their blades after water flow stops for even a few minutes or less. Make sure you take off the front of the heat exchanger and remove the failed parts that could block some of the cooling tubes.

[Markus]

On my 40 cc I have had a water flow switch in the raw water supply upstream of the heat exchanger . Any interuption in the flow brings on an alarm . In the past many years it has detected several disruptions including my failure to open the seacock. Cost about £12 from I think RS componants and has proved its worth . Geoff

I've got a pretty bulletproof system that's even cheaper than that: when ever I close the engine seacock, I put the engine key hanging from the seacock handle... 

[Petef]

I've got a pretty bulletproof system that's even cheaper than that: when ever I close the engine seacock, I put the engine key hanging from the seacock handle... 

Great idea but don't have a key, lol I just press a button

[PEA-JAY]

You have an engine main switch though, with a detachable L shaped knob 😉

[Petef]

You have an engine main switch though, with a detachable L shaped knob 😉

  True, but sometimes the rear admiral does those. Guess I can put a label over it lol