1980 40hp impeller bits and pieces

Hi , I'm working on my Dad's 1980 40 hp mercury outboard. It has been parked for the last 20 years. it fired right up but wasn't cooling. so I installed a new water pump repair kit and impeller. all of the old impeller blades had disintegrated or broken off and i managed to recover three of the blade ends and matched them to where they came from. as for the other three, I don't know where they are. the engine runs good, water streams from the tell tale hole, and water is blown out with the exhaust from the prop.
should i persevere with my search for the bits? I've read the other post on backflushing the system and I'm ok with that if it is necessary, but I'm not sure where the thermostat is.
any advice would be appreciated. Thank you.

Re: 1980 40hp impeller bits and pieces

Welcome to iBoats plumbob.
The remains of the impeller could be anywhere. You might drive yourself nuts trying to find it all. I think the thermostat is on the top at the back of the power head. Maybe someone knows how big the orifice is where the water enters the power head. On one of my old Rudes the water passed through a hole in the adapter plate about 1/8" diameter. No large chunks would get by that.