Hello,
I recently bought a used fountain with a 496HO. I Live in Michigan and it gets cold so I am trying to winterize the boat. I am reading that I need to use an air pump. unfortunately, I do not have one. What exactly does that air pump do? Can I just run antifreeze thru the engine and be alright. Is there any other way to winterize the engine without the pump.

Any details will help.

Derrick

There is a blue plug underneath the P/S pump, 2 blue plugs on the raw water pump, and a plug on the cool fuel assembly. Drain those first then run antifreeze through it. Also, check your freeze protection in the closed cooling portion of your cooling system.

Do a search, this has been discussed a MILLION times.

The air pump evacuation system is a temp/quick water drain solution to extend your boating season. All you need is a bicycle pump to open the valves. The air pressure only opens the valves, it does not pump the water out. Look on the front of the heat exchanger for a small blue pump in a black plastic clip. They all came with them mounted there. It's about the size of a small flashlight. You can do this with a tire fill tank as well. It only takes a couple pounds of pressure. I use a 12V compressor/battery box.

FULL WINTERIZATION:
You are on the right track. For where you are in Michigan, you DEFINITELY want to run antifreeze though the sea water side of the engine. Added benefit of the air valve system mentioned above, you can drain the majority of the water out of the system BEFORE you run antifreeze though so you don't have to worry about dilution.

it depends on which cool fuel system he has how to winterize it properly and the Gen III cool fuel 2008 and back will not have any blue drains plugs. You still have to drain it regardless or you run the risk of cracking the fuel cell water portion sections.

Also all marine engines goes by engine serial number runs as to per set up and parts used - not year model. Just saying. and again all Gen III Merc cool fuels have to be completely drain properly fo cooling water before it freezes. Good luck.

Gen II cool fuel systems will have a blue drain to drain them.

Yep. I froze and lost a heat exchanger one winter on my old 496 by relying only on the air pump method. I like to pull some hoses off and let everything drain that way. Pouring some antifreeze in wouldn't hurt either.

<------ air pump / blows out the system. Then runs pink juice threw via 5 gal jug, short hose and muffs till pinks comes out the exhaust.

That was a $1200 mistake.
Winterization is a great time to pull the end caps off of the Heat Exchangers and clean out all of the debris. at the end of the tubes. It's really easy. I'd buy new gaskets before you pull them off.

Just to clarify...
The air pump system does NOT pressurize the sea water side of the motor to displace water.
The air pressure opens two spring loaded drain valve actuators. The water drains out with gravity.
It does NOT drain every bit of water out of the system, as mentioned.

+1 on the 5 gallon jerry can with short hose hooked to muffs. drain water first with air pump then release air pressure to close valves then run on muffs with jerry can sitting on swim platform till all 5 gallons gone then drain system again with air pump and done. Use RV anti freeze.

Is it necessary to cycle the switchable exhaust / captain's call when running/flushing the engine with the non toxic antifreeze? My exhaust runs through the transom unless I engage the switch to run exhaust through the hub. Can water pool (and freeze) downstream from the y pipe?