Hi guys, my 454 alpha is running at a steady 185 degrees water temp at idle which I believe is way over the top.

Any ideas on how to bring this back down?

Sounds like your drive impeller is on it's way out. Very easy to change...if it has any time at all on it replace it. Other than that a faulty thermostat could be your problem...but understanding your engine is fresh this is not likely.

That temp is high, but you are not damaging the motor. Just do not run it like that for very long. Remember that engines in cars/trucks run between 180 and 212 all day long. Just get it fixed and you'll be fine.

The sterndrive is freshly overhauled so had ruled out the impeller. The thermostat is also new.
Any more thoughts? Could running too lean cause this?

Check the hose running from the drive, up through the transom, could have kinked it when replacing the drive.

Just because things were overhauled does not mean the impellor did not go bad. If you trun those dry for more the 10 seconds, they will go bad. If the muffs slipped off or if you had issues with initial start-up, it could be bad. Just a thought...... Personally I would start there being as it is the most obvious. Then pull the thermstat and see what happens. Not sure about the "to lean" potential...... NOrmally that would be a problem under a load and I do not think so at idle... Anyone?

put boat in water. not running off garden hose. take off hose from transom to thermostat housing. start engine. look at stream of water coming out of hose. it should be as fat as the hose and flowing well. hit gas and it should shoot out farther. i guess somebody needs to take a correct running one and fill a 5 gallon bucket at idle and time how long to fill at what rpm. this will tell you if you have enough water to cool engine. it is possible there is no thermostat at all. sometimes the water goes right out exhausts w/o stat and doesn't leave enough behind to cool engine at idle. you can't use hose for this test because house water pressure will throw off results.