Ok, well I have only ran it for about 10 minutes with the new and not above 1200 rpm sea water pump in. I don’t think it’s damaged. I’m going to drag it to a local lake and see what happens. Thanks for your input and knowledge. I’d be really lost right now without this OSO community.

I've seen Bravo water pump impellers get damaged in well under 1 min if run dry. You may have gotten lucky and got a little water thru it, but be aware.

Last boat had an Alpha drive I put into a 100 gal horse watering tub. After abt 10 mins, the water in the tub was steaming.

I chased a overheating / overcooling problem for 2 seasons. it was the 1 part everyone said "it couldn't be".

Thermostat housing. It was leaking water between the top/bottom.

Not saying that's your issue, just something I'd check, if it's 30 years old.

More info on this leaking water from top to bottom please and what where the symptoms, just overcooling as your vid states ? But you say above overheating too ? . Thanks.

[QUOTE=SabrToothSqrl;4791598]I chased a overheating / overcooling problem for 2 seasons. it was the 1 part everyone said "it couldn't be".

Thermostat housing. It was leaking water between the top/bottom.

Not saying that's your issue, just something I'd check, if it's 30 years old.

These thermostat housings are very hard to find and becoming very rare. I was able to find one on eBay that was in a little better condition than mine. So now that is replaced, ran it on the hose tonight and temp seemed to hover around 155 for a bit and then began to climb. I’m going to drag it to a nearby lake tomorrow and see what it does.

check for loose intake hose clamp at transom

I had a similar problem, it turned out to be corrosion between the Outdrive and bell housing around the O-Ring that seals the two surfaces, air was getting sucked in.

Air: Problem: No Air: No Problem:
you run a hose first from water IN to make sure air isn't getting TO the engine. If that's clear (no air), then move on to water leaving the engine. Mine had air. (bad!).

[QUOTE=90MirageTrovare;4791629]One of the reasons I sold my 1990 Chris Craft 245 (God I loved that boat) with an OMC 460 was... parts did NOT EXIST ANYWHERE at ANY PRICE.

Now I have 2 Merc 350s and can walk into any WalMart, anywhere and get parts...

I know that's not what you want to hear... just what happened to me. If you have the original part, maybe you can custom make a new one or adapt something else? For my OMC460, I told Advance Auto I had a 1990 F250 with a 460 to get parts sometimes when nothing else would work.

If it's not a cooling issue - and it's actually an overheating issue - have we checked oil level? compression? clogged passages within the engine?

While floating in the boat (on land isn't a valid test) there is a test in the manual that you disconnect the raw water IN at the boat, and direct the hose to a bucket, with the engine running and measure how much water you get within (I think 60 seconds)? I'm not sure what the numbers are, but if you get X amount of water it's within spec and 'good'.

From what you just said, it sounds like you're overheating at idle, under no load... that's interesting. To me that would make me think clogged cooling passages. At idle the cooling system is WAYYY more than you need to keep it cool. (since it obviously cools under heavy load). So.. hmmm... any loss of oil? I'd ask for if a sweet smell to the exhaust, but boat's don't (usually) use antifreeze.

this is a tough one.

Chasing a ghost
 

Well I guess snapmorgan was right! Ran all day yesterday around the pnw sound. No overheating problem. Thanks everyone for all the advice, at least I know my boat a little better now 🍻