Empty vs full block for winter storage.

Nauset

Member
Joined
Sep 15, 2006
RO Number
23391
Messages
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Has anyone ever seen a study that was conducted to compare the effects of filling your engine with antifreeze or not filling it? The instructions that come with my Four Winns/5.7 Volvo Penta say to just drain the block, manifolds, etc and you are done. I go one extra and pour in AF to purge out any water that may be left in the water jackets. I find it hard to believe that the cooling system will rust up in 6 months by sitting empty, especially in a fresh water boat. If that is the case wouldn't they tend to rust more in summer when full of just plain water with no rust inhibiters. I read the posts here and it sounds like people are going overboard hooking up muffs, filling their engines, removing thermostats, etc. I wonder if it isn't suppliers spreading misinformation to sell more antifreeze and winterization kits.
 
I'd be curious to hear how storing a saltwater engine dry effects it, as well.
 
They do rust plenty in the summer when full of raw water. Ever not use the boat for a time, fire it up and see the rust come out of the exhausts? I like knowing that I'm at least slowing the rust process down by the few months a year the engine is filled up with anti-freeze with corrosion inhibitors. It's too late for me to convert to FWC and have antifreeze in the block all the time. And it's not just the cooling system, it's the entire block too.
 
I had a fresh water 4 cyl. merc for 17 years. After 15 years the head had to be pulled for service. There was no more than surface rust in that cooling jacket and head. I never did anything but drain the water. That was in the days b/4 non-toxic a/f. That's how we did it and I don't believe the cast iron is any different today. If you're in salt water I cannot speak as I have no experience with that. Tom
 
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