Winterizing a 5.7 liter merc & deck boat

Hello All,

Looking for some advice on winterizing my 5.7 liter Merc motor and the pressurized on board water system ( New to me). In the past (Other Boats) I would start the engine with the muffs and water, let the motor warm up and then shut down. Replace the water with antifreeze and run about 5 gallons of antifreeze through the motor, shut the engine down and call it complete. The guy at the marina said I should fog, the engine as well? What does that include? Also, this boat has a port a potty head and a water holding tank, 2 sinks and a water pump, any advice on this as well? First year with the new boat...

Thanks,
Chet

Re: Winterizing a 5.7 liter merc & deck boat

Take it to a marina, let them do it. If they screw up it's on them not on you. I always let them do it.

Re: Winterizing a 5.7 liter merc & deck boat

Ayuh,... Drain All the water from all of the boat, 'n call it a season...

Air don't freeze...

Re: Winterizing a 5.7 liter merc & deck boat

Let the marina do it all. If you're lucky (and nice) they may let you watch and learn so you can do it next time.

Re: Winterizing a 5.7 liter merc & deck boat

Three schools of thought - you need to pick one.

1. Drain all water from boat (manual should walk you through the procedures to do so).
2. Add antifreeze to any water in the boat.
3. Take it to a marina and let them do it for you.

As for fogging, I've never done it. Some people swear by it, I just never saw the need for 5 -6 months of storage.

Re: Winterizing a 5.7 liter merc & deck boat

I use the RV antifreeze, from Wally World. As you said, I get the engine up to operating temp, so the thermostat opens, then shut down and switch over to the antifreeze through the muffs. Fire it up and run it until the exhaust water turns pink. I did 4 boats and a Sedoo that way last fall and it worked fine. One of the boats has drains on the manifold elbows, so I pulled the plugs on those after the antifreeze flooding, but on the others I didn't. None had a problem.

Use the RV antifreeze that has a corrosion inhibitor in it, so that it will reduce or prevent corrosion in the engine all winter.

Only one of those boats has a fresh water tank and porta-potty. Both were completely empty, so there was no need to winterize there, but you would use the same non-toxic RV antifreeze in those.

As far as fogging goes, I just dumped new motor oil down the carb until the engine cut off, once the exhaust water turned pink, and she was "fogged". My buddy didn't fog his, and those boats sat beside each other all winter long, then in the spring, his started without smoke. Mine smoked like a freight train for a minute or two. I don't know that it is a huge advantage to fog, but I figure for the little effort and cost, might as well. Surely cheaper than a new engine.

On a funny side note, my buddy's brother says that winterizing is for sissies and sold his boat after the SECOND block cracked over the winter. He won't wear sun screen either, because only sissies don't look like boiled lobsters after a day on the water. :facepalm:

Chris

Re: Winterizing a 5.7 liter merc & deck boat

I just drain all the water out of the system and that's it. (It gets down to -20F here and I've never had an issue). With the quick drain systems that the newer mercruisers have it takes 5 minutes. As for the fogging, I've never seen the need for fogging the motor or dumping any snake oil in the gas. Boat starts right up every spring with no issues.