without knowing the water flow routing its had to say, Ive seen engines lose an impeller and never get flushed out, it stays in there forever, take a look at the sea pump

I got the sea pump out and the impeller is not missing any pieces. So I think it’s safe to says it’s the thermostat. What do you guys think?

Change the impeller, wear plate and thermostat. Other than that check your recirculating water pump.
Too bad you cannot ask BUP for professional advice.

Thank you for the help everyone

I did replace the impeller, housing and wear plate

I also replaced the thermostat. Now I just have to take it to the water to test it. Fingers crossed.

One other thing I did see a broken mystery attached to the top of the transom any idea what this should be attached to?

Are the manifolds and risers stock cast iron? How old are they? If they are at the end of their life span, they can cause overheat.

Typical blockage is in the entrance of the engine oil cooler. As Speedy noted it had little tubes the water must go thru. Small rocks and etc can collect here too.

I’ve worked on a handful of boats with impellers in decent shape that had bunch of impeller pieces blocking entrance to oil cooler. How does that happen ? Humans. :) Not removing the pieces doing previous impeller replacements.

As just noted above, exhaust manifolds and/or risers can be corroded enough internally they are not passing enough water. After checking all other things - impeller and housing, blockage at cooler, recirc pump impeller, bravo-itus hose fitting corrosion/restriction , and etc.....may be time to pop off risers to take a look see.

Any chance your boat was used in salt or brackish water ?

Sorry for the long time to update. So I changed the impeller and the thermostat (which was stuck closed) yesterday had the boat out all afternoon running at all kinds of speeds with no alarm sounding. On the way back in which is about a 45 minute ride in no wake zone, about 4 minutes from the dock the alarm went off (not a steady alarm, I would say one second then a three second pause) all the gauges read fine. Water temp all day never got above 175 most of the time it was around 150-160. Is it possible it could be a bad sensor somewhere giving a false alarm? So Frustrating