70etlh alarm at slow speed

[CharlieHorse]

The alarm comes on at ***** speed but goes clear at wake speed or higher. Water pump or thermostat? Stream appears to be good. A repair shop said they changed the impeller but it still had the alarm afterwards. The bolts on the lower unit do not look disturbed to me.

[boats.net]

Start with the water pump.

[CharlieHorse]

Thanks. Just changed the pump kit from boats.net yesterday. The tell tale still looks good (about the same) on a hose. The olld impeller had cracks where the blades bend. Taking it out tomorrow. We'll see!! Thanks again.

I would like to check and/or replace the thermostat as well (never changed as far as I know in 25 yrs). Is it difficult and is there a video anywhere? Thanks.