you inadvertantely posted in a Webmaster generated thread dated April 2025. I jut happened to see your post. You will get better response if you start your own thread.
There are a lot of reasons why outboards don’t cool even after a new impeller has been installed. a couple of common ones are: The water tube didn’t get inserted into the grommet at the water pump. There could be a blockage somewhere in the cooling system from broken pieces of an old impeller, corrosion, etc. Maybe the impeller key isn’t in the slot or maybe the impeller has spun on it’s center.
If you test run prior to going to the water you should be able to observe water exiting the exhaust relief or “telltale” if so equipped. You can use a digital thermometer to measure the temperature of the block during this test run.
