This is my first time winterizing this boat and I'm puzzled. I had both engines warmed up using the garden hose with an adapter that ties into a Y pipe at the back of the freshwater pumps. No issues and water exiting the exhaust tips as expected. I disconnected the freshwater source and using a 6' section of garden hose attached to the same port tried to suck antifreeze from a 5 gallon bucket. I was working alone and unaware no fluid was passing out the exhaust tips and the temperature came up to about 170 and I fried the impeller before shutting it down. The impeller only had about three hours on it. Am I wrong in assuming that the water pump can create suction? Or does it require pressure in order to circulate?

EDIT: I think I figured it out but I'm interested in any comments except those telling me I'm a dumba$$. I need to close the raw water intake valves.

Needs pressure to get to sea water pump. I use a bilge pump in a bucket to get water to the pump. Gravity feed will not work and distroy impeller.

If this is true, how does it work sitting still in the water at the dock?

This is exactly why I edited my post after scratching my head about it. Reason it's working on the garden hose is because the water pressure is overpowering the volume of the impeller. Once I remove the pressure by using the hose in the bucket of antifreeze the impeller begins sucking air from the raw water inlet.

bucket has to be higher than pump and it will absolutely suck a 5 faster than you'd believe

maybe you'll be lucky if there was no water / fluid in the pump the pieces won't be jammed upstream in the coolers

Bucket was in the cockpit and was higher than the pump. I've changed the impeller and have accounted for all the pieces. Now I need for someone to confirm that the cause was not having the raw water inlet valves closed, letting them suck air.

you are correct. I've done this many times. It don't take but a second to see your antifreeze level dropping. Sounds like you have this figured out. Good luck

Make sure you pull the drain plugs on the sides of the block to drain the block before you run the antifreeze through it.

Apparently the raw water pickups are in my Bravo nose cones, so no raw water pickup or valve close. I am baffled at how the water pump will draw water at idle sitting in the lake but not draw water from the aux hose water port out of a bucket. The aux port is plumbed into a inlet "Y" at the back of the water pump. Boat is a Formula 353c any ideas?

Any pump will draw air easier than water. The garden hose works because the pressure being fed. Use a bilge pump or freshwater pump to feed the antifreeze and you will be fine.