Why did my water pump stop working?

Question

I replaced the impeller on my 40hp Suzuki outboard. It worked fine for about 15 minutes. The stream started getting weak, then quit all together. I tore it back down and the impeller is fine. No trash is visible. Any suggestions? Thanks

Answer 1

three possibilities come to mind:

Forgot to replace the woodruff key.

Piece of the old impeller broke off & blocking the water jacket.

Bad thermostat.

To get to that thermostat, both the cylinder head cover and the cylinder head have to come off.