Mercury Mercruiser 3.0 inboard/outboard - help!

[Classic]

Ok. So had my boat out of the water being serviced. Got it back and it was a nice day today so decided to put it back in water at dock. Dropped off trailer into water and drove it about 15 minutes to dock. When I realized the bilge was running constantly. Looked into engine compartment and its 1/4 filled with water. Drove it back to ramps and pulled it out. They didn't put the drain plug back in. Found it on boat and put it in. Put boat back in water and drove it back to dock. Shut her down, verified water wasn't coming in and went to disconnect the quick drain hoses, to drain the water from block and manifold. Pulled the back seat forward, and of course they are disconnected. So they were disconnected the whole time I was driving boat. The thermostat wasn't working, I stupidly just assumed they damaged the gauge. Now I realize it was because there was no water running to thermostat. I haven't started it again yet. Figured I'd let it cool down. Now I'm wondering what kind of damage was done. What are the possibilities? What needs to be checked? Hopefully it's a good sign she was still running, and I'm hoping the water in the engine compartment helped keep her cool. But I have no idea if she overheated or if any damage was done. Any help or thoughts would be appreciated! Thanks!

[badmoonrising]

Do you have a temperature gauge ? As long as it didn't get very hot you'll be fine - BUT. The water tube inside the drive is plastic. The exhaust flapper is rubber. MOST times the 3.0s are overheated the rubber flapper melts and takes out the water tub with it. Go home, put it on muffs and start 'er up. If water flow is good out the reliefs and exhaust you should be fine. If the seawater temp was cold, you probably didn't get the engine warm enough to cause damage.

On muffs, the temp gauge should stay under 165 after it fully warms up.

[MH Hawker]

MY first call would be to whom ever did the work. And it wouldn't be a present call.

[Bamaman]

Those engines are pretty tough.

At a minimum, I'd want a qualified marine mechanic to inspect the engine when all hoses, etc. are hooked back up. I'd at least want a compression check and a vacuum check which can give some info on the valve train condition, etc.

A quality shop should agree to fix your boat IF any problem comes up within the next couple of years.