Winterize - Help Noob Verify - 1998 5.7L Carb

Hi Moomba Team,

First year owner of a 1998 Moomba Mobius with Indmar 5.7L Carb 310HP. I have read just about everything on the forum and winterization but hoping you veterans can help assure I've hit everything.

As background, the boat was test driven before purchase and I've had it out once myself for 4 hours of use with no issues.

To start:
1 - Added Stabil to a full tank of fuel.
2 - Connected garden hose to raw water intake and ran for 20 minutes to raise temp.
3 - Disconnected garden hose and ran on funnel with 5 gallons of RV antifreeze.
4 - Disconnected both hoses to fresh water pump and hose to lower thermostat housing and drained. Pictured here in Blue.
Attachment 26422
5 - Removed 4 drain plugs, block left/right and Exhaust Manifold left/right.
Attachment 26423
Attachment 26424
6 - Fresh water intake is disconnected and drained.
7 - Removed impeller from pump.
8 - Done.

The impeller I took out was intact and appears to be new but when I drained the exhaust manifold ports, rust and chunks of old impeller came out (see picture). Does their presence in the exhaust mean I should check elsewhere (thermostat housing) for more chunks?
Attachment 26427

Lastly, help me identify this part. Indicated by the red arrow and circle. It looks like its been removed in the past with a pair of channel lock pliers. The collar of it is sorta chewed up and stripped of black paint.
Attachment 26428

Thanks for the help.
Mark

Welcome aboard. Interesting you got that large of chunks out of the manifold drain holes. A small amount of rust is normal. The plug on top appears to be a sensor and nothing for winterization. I didn't see any heater hoses in your pictures. Next year, I would recommend fogging the engine through the carburetor as it is easy to do. In the spring I would recommend using a carb cleaner as a good operating carb makes for a happy engine and operator. That year boat had two different type engines the Indmar and the Pleasurecraft which I have so when ordering parts remember to specify which type.

The mystery past its the low oil pressure cutoff switch. The two empty tabs mean you probably have two wires jumpered together to bypass it.

I would take a wire and poke your drain holes as sometimes rust can block and prevent all the water from draining. Not sure why you sucked up the antifreeze before you drained it as most of it would have bypassed the block and went directly to the exhaust manifold and out to the mufflers. Next year do it and compare the colour of the exhaust manifold liquid to the block liquid.....the block will be substantially lighter than the manifold.
But you look good for the winter as far as the motor