I almost cried...

[Moor]

Yeasterday it was finally warm enough to pull the cover off and unwinterize the tow rig. As i lifted up the dog house i saw one of the worst sights a boat owner can see. I was an unusually long and cold winter, and my heart sank as i saw a freezout plug lying in the bilge. So i started prepairing for the worst. Let me give you all the back story: last fall i had to move unexpectedly, and the boat winterization got put off until the last minute. You know, the "oh sh*t its going to snow tomorrow, i better winterize after work" kind of last minute. One of the drain plugs on the block, down by the engine pan, was stripped. No way i was getting it out where the boat was. So i filled the cooling system with antifreeze, ran the engine and sucked up a 5 gallon pale of coolant. Fogged it to shut her down, topped off the coolant, pulled the impeller, hoses and finished up the winterization.
so i Ran down to the Local Napa, bought a new freeze out plug and installed it with a just a dab of rtv to make sure it seals good. reconnected all the hoses and plugs and fired it up. It ran for about 5 mins on ym home made fake a lake, and everything seems ok. No milkshake in the oil, no leaks, no immediate overheating, so i THINK im in the clear. I guess i'll know for sure on the first test drive of the season.

On a side note, I notice A LOT of scale and deposits in the cooling jackets of the engine block when the freeze out plug was out. I cleaned as much out as i could, but theres still a ton in the engine. its also building up in the exhaust manifolds. Does anyone know a good way to flush/clean out the cooling system?

[CJD]

Interesting...

The correct term for those plugs are core plugs, as their purpose is to plug the holes used for removing the sand cores after casting. I've had a lot of engines that have frozen, but never had a plug pop out. Normally a freeze cracks the block along the sides on the relatively flat areas below the heads.

A lot of scale inside the block is normal. Remember we are running straight water for cooling...well, most of us anyway...so iron is going to rust. If you clean it out, it only provides more fresh iron to accelerate the corrosion.

[2001Sunsport]

Don't be too confident you are good yet. I had someone who had a core plug pop, replaced it, and thought they were good because it ran find on the hose, but once they got out on the lake and put it under load they got water in the oil.

[Zim]

Well, if you had a plug pop, it did it's job. Yes, they're technically core plugs, but they do also give way first in a freeze. Hopefully nothing froze too much in the water jackets, but the freeze plug could have saved you. If you used RV anti freeze (the pink stuff), it has a freeze point of -50. If it's diluted at all, that drastically decreases. That RV antifreeze turns to slush pretty quickly at around 0*F, and will freeze solid at -50. Any water mixed with it will affect those numbers. It could have become slushy earlier, and frozen over in full in as little as 0*F, but hopefully it didn't stay that consistency for too long.

Keep a watchful eye on that oil... like every hour check it. If it gets chocolate milky, you know what's up. Also look for abnormal amounts of oil in your bilge, or any fresh dripping areas in your bilge as well.

This is why I drain my block. I know your block plug was stripped, but if nothings in there, it can't freeze.

[docdrs]

The only way to get antifreeze into the block by sucking it up is to have an empty block!!!!!!... anything less than 170 degrees will not have the thermostat open enough to let any block water out and any antifreeze in thru the circ pump.......this is why this method should never ever be used!!!!! As above, any dilution of antifreeze will render it ineffective to prevent freezing!!!!!!! I have run the numbers, you are just kidding yourself if you think this works ! Unless you have 100% strength antifreeze and a hygrometer.

[wotan2525]

The only way to get antifreeze into the block by sucking it up is to have an empty block!!!!!!... anything less than 170 degrees will not have the thermostat open enough to let any block water out and any antifreeze in thru the circ pump.......this is why this method should never ever be used!!!!! As above, any dilution of antifreeze will render it ineffective to prevent freezing!!!!!!! I have run the numbers, you are just kidding yourself if you think this works ! Unless you have 100% strength antifreeze and a hygrometer.

I'm not sure you've used enough exclamation points.

I'm also completely fine with you doing whatever makes you happy with your boat. For me? I go the RV antifreeze route.

For me? I remove my thermostat (good excuse to inspect it and test it, anyway.) So my block is full of RV antifreeze. And yes, if it's diluted with fresh water it will be less effective. That's why I try to "flush" out the water with an extra 2-gallons of RV antifreeze.

Now, I understand I may look foolish in a couple of weeks if the boat comes out of storage and I have to eat some crow -- but I've been using this method for 10 years and my father has been using this method for 20 years before that. And we've yet to have a problem.

And we're in a part of the country that sees far colder temperatures than most on here.

My point? Do what makes you happy. But the chances of a catastrophic block failure from using RV anti-freeze the proper way is very low!!!!!!!!!!!!!!!!!!!!!!

[Zim]

Anti-freeze has its applications. It helps prevent corrosion, but I'd rather have a little corrosion than a busted block. The best way to use antifreeze would be to suck it up without a thermostat in, then drain the block. Then suck up more anti-freeze. That'll get the most water out, so you have the strongest concentration of anti-freeze to water ratio.

[docdrs]

I'm not sure you've used enough exclamation points.

I'm also completely fine with you doing whatever makes you happy with your boat. For me? I go the RV antifreeze route.

For me? I remove my thermostat (good excuse to inspect it and test it, anyway.) So my block is full of RV antifreeze. And yes, if it's diluted with fresh water it will be less effective. That's why I try to "flush" out the water with an extra 2-gallons of RV antifreeze.

Now, I understand I may look foolish in a couple of weeks if the boat comes out of storage and I have to eat some crow -- but I've been using this method for 10 years and my father has been using this method for 20 years before that. And we've yet to have a problem.

And we're in a part of the country that sees far colder temperatures than most on here.

My point? Do what makes you happy. But the chances of a catastrophic block failure from using RV anti-freeze the proper way is very low!!!!!!!!!!!!!!!!!!!!!!

Your right everyone can do what they want. I am just informing people that not draining the block and sucking up -50 plumbing antifreeze does not give adequate protection against -20 degrees. Here it is by the numbers.

Your typical inboard has about 5 gallons in its cooling system( I have personally measured it). When the temperature is 160 degrees the thermostat just starts opening allowing hot water to escape from the engine.( take a tstat and put it in water on a stove with a thermometer and you will see) The rest of the intake fluid will bypass the circulating pump and flow out the exhaust manifolds and mufflers. If you have the CONCENTRATE which is 95% then yes you only need 2 gallons of it fully circulated thru your engine to achieve a 35 % concentration for -50 protection. But that is fully circulated , not just sucked up (and by the way it is pushed into the engine at a low idle flow rpm). If you use the -50 stuff which is 35% then you would need 30 gallons fully circulated to achieve a 32% which would give you -35 protection. A 17.5% solution of propylene glycol will only give you 15 F burst protection......so if you were to use 5 gallons of -50 fully circulated not just sucked up you will have a 15 F protection temperature.

So my question to anyone who insists on your method is why don't you just remove the block drain plugs and drain the block first. Far easier then removing thermostat housing ,reinstalling ," flushing " or whatever your exact procedure is. That's why the engine manufacturers put drain plugs there. Some even have gone so far as to put quick drains on them. Why risk a $10- 15,000 motor for something that is so simple.

[Moor]

Yes, i did use the pink RV coolant. I also removed 3 out of the 4 block drain plugs, so most of the water was drained out of the block. I used a 5 gallon pale to suck up the pink coolant into the engine. i DID NOT remove the thermostat, so maybe i didnt get as much coolant circulating through the block as i thought. I've inspected the intire external surface of the block and see no signs of cracks. I sold an old 454 barfoot nautique to a friend a few years ago, and he froze the block the first winter he had it, so im familiar with where they crack. It was below -0F for almost 2 weeks straight this winter, so with the 1/2A$$'ed winterization my boat got im not suprised it blew a freeze out plug. Its been in the back of my mind all winter. Maybe if i used a regular automotive concentrated coolant i wouldnt have push out a freeze plug, given the lack of circulation/coolant that was in the on part of the block that i could not drain. I'll keep a close eye on it for the first few boat rides and cross my fingers for now.

So i shouldn't be concerned with all the rust/scale inside the coolant passages in the block/exhaust manifolds? My engine has never ran warm, infact it runs on the cool side, so its not effecting the cooling efficiency, but it cant be good for it circulating in the system/pump.

[CJD]

So i shouldn't be concerned with all the rust/scale inside the coolant passages in the block/exhaust manifolds? My engine has never ran warm, infact it runs on the cool side, so its not effecting the cooling efficiency, but it cant be good for it circulating in the system/pump.

Nothing to worry about. The rust scale will work its way through and blow out the exhaust. In time...like a whole lotta time, all our blocks will rust through, but the risers will be the first to go. They see more heat, more air, and more corrosive combustion by-products than the block does. You should go through 2-3 risers before the block goes away. Now, some scale will settle to the bottom of the block cooling passages...and that is a secondary reason for draining the block every season, as it frees any trapped scale.

You do need to schedule some time to replace the stripped plug. Never tighten the plugs past snug, and you'll never have an issue with stripping them in the future. If a plug leaks, use teflon tape to seal it rather than cranking down on it...and really, a small plug leak won't hurt anything anyway.