Frozen heat exchanger on 37 470

"I recently purchaced a boat w

"I recently purchaced a boat with a mercruiser 470. After talking to people and asking around I was told that when done running the motor the water will run out of the outdrive. I have a exhaust manifold gasket that needs replacing, so when I was looking at the exhaust gasket, to my surprise there was frozen water coming out of the side of the heat exchanger. I remover the complete heat exchanger and brought it inside to unthaw. Hopefully the heat exchanger isnt ruined. I dont know much about this boat, but I know thats got to be an expensive part. Any Information would be greatly apreciated. Do I need to do anything else to the engine so nothing else freezes. The antifreeze level is good for -30. Do you think I will be able to just replace the end cap?, and how can I tell if the heat exchanger is damaged? it wasnt frozen completely solid ,but pritty close. does anyone have any sugestions. Thanks"

"You can get the exchanger pre

"You can get the exchanger pressure tested at any rad shop. That should tell the story.
Is there no drain plug on the seawater side of the exchanger? Usually there is a combination drain plug/corrosion anode along the bottom on one end of the exchanger so you can drain it completely when winterizing.
Good luck,
Rod"

"Hopefully all that happened i

"Hopefully all that happened is the o-ring that seals the end cap failed and nothing else. You definately want to test it once the o-ring is replaced. If it popped a tube, that would give it a path to have raw water contaminate the fresh water (coolant) side and allow coolant to leak out.
I'm assuming this is an Alpha 1 sterndrive.
Seems odd that it didn't drain out through the outdrive... do you lower the outdrive (full down) when you get it parked and leave it sit?
You may want to take a look at the power steering cooler (if equiped) too."

"I own a 1980 470 Mercruiser.

"I own a 1980 470 Mercruiser.
When I bought it, the dealer installed drain valves on the stern end of the exchanger as well as on the side of the exhaust manifold.
Every winter, I open the valves to drain the exchanger and exhaust manifold.
Never had a problem as the drain is at the lowest end of the heat exchanger.
Hope this helps for the future."