Carver Owners Forum

Closed cooling means the engines are filled with antifreeze and therefor protected from the evils of winter assuming the antifreeze is up to spec. The only thing the raw water does is cool the antifreeze via a heat exchanger which basically replaces the radiator on a car. I also have closed cooling however different engines but it does remain the same procedure. Most simply unscrew the strainer cover and pour the pink stuff into her while the engine is started and run. I went a step further and machined a new strainer cap with a barb style hose fitting on the end so I use a 5 gallon pail of the ink stuff connected with a hose to my machined cap and fire her up. That is it for the engines.

Make sure you check the anti-freeze rating on what's in your closed cooling system. You can get a tester from any auto store, but make sure you get the right one... there's one for polypropylene glycol and one for ethylene glycol.

Otherwise, what midnightsun is right... you're wanting to get the antifreeze in the raw water pump and any heat exchangers. If you've cycled enough antifreeze into the system, those should be covered.

I don't have mufflers on my boat, but I've often wondered... are those all self-draining??

Don't forget about all the other winterizing... the heads, the potable water, the HVAC systems, icemakers, etc.

Also... made the mistake one time of not cycling my through-hulls after I got out of the water. I winterized the engines before I got pulled out by the hoist and had the seacocks closed. Apparently there was some water trapped inside the seacock that froze over the winter. Simple solution... after you're 'on the hard', then cycle them open and shut at least once.

Drain ALL the water out of the raw water circuit of the engine, especially if you're using cheap antifreeze. Remember, not all antifreeze brands are alike, there's a reason why some are more expensive. If the exhaust manifolds are raw water cooled, drain them also as well as your strainers. Don't forget to probe the manifold drains. If you have mufflers with drain plugs (most do), drain them first too. This way there is very little chance of dilution which has screwed many a DIYer. Pour propylene glycol in the strainer while the engine is running. When bright pink antifreeze exits the exhaust, you're raw water circuit is winterized. Do the same for the generator.

There's more to winterizing engines than just antifreeze, including fuel filter replacement, fuel stabilizer, etc. I'm sure a lot of threads on this topic will pop up soon so stay posted. Oh, and don't worry about t-stats not opening, raw water cooled or not, it's not a concern but only if you drain all the raw water.

PS; sea-cocks should be left open, and because they can leak when closed after you winterize if done in the water, because of that I don't winterize in the water, I wait until the boat is out, but that's another thread.

nautiyachti wrote:Source of the post So this is my dilemma, I'm hearing drain then fill with glycol, and others say just run the glycol through the engines via strainer.

Midnight Sun I see your in Montreal which get cold winters, how many years have you just been just running glycol through the system without draining beforehand? Also what type and brand glycol have you been using?

Thank in advance

My previous raw water cooled gas engine I simply drained them without using anything as I go by the fact that air don't freeze. The Carver with it's closed cooling as I mentioned above requires only draining of the heat exchanger system as the engine is already well protected with glycol down to -40.

Back to the exchanger, I would never use glycol (green car anti-freeze) in there as it is poisonous and will get into the water come spring, there is just no way of collecting this on the exhaust system on my boat as there are actually 2 under the hull and another 2 above water on each side towards the stern. You do need to look at your mufflers as I do not know what you have. On the Volvo diesel setup they are self draining so I luck out there and do nothing but as mentioned, you may need to drain them via a plug. Bottom line is after flushing with the pink it self drains so almost nothing actually remains in the system. I do this more for piece of mind than anything else as those darn diesels are a fortune to rebuild!

I use the pink stuff or RV anti freeze if you prefer. You do want the one that says it has corrosion inhibitors, brand is not important IMHO. All the stuff around here is good to -40 also. This is the same stuff I will run through my potable water system and my wash down system.

That being said I did remove the drain plugs last year (first winter of ownership on this boat) but do keep in mind this is on Volvo D6 diesels so your application will probably be different. There was so little water that came out it was not required IMHO so this year I will not be draining, just running the pink stuff through.

On the whole "corrosion inhibitors" thing. If you have any actual info or links on this, I would appreciate it. I had quite a 'lively' discussion a couple years ago at West Marine when they insisted the more expensive PG bottles had "corrosion inhibitors", rather than just a higher concentration of PG. I got them to dig up the MSDS sheets for all the different bottles and NOTHING else was listed except PG and water. A bottle full of PG is a corrosion inhibitor!

That's surprising coming from West Marine given that they carry both types of PG. The cheaper stuff is for "plumbing" only, the more expensive stuff will specifically state that it is safe for winterizing plumbing AND engines. There IS a difference in the formulation. Cheaper antifreeze for plumbing only is rated for plastic pipes/hose and is NOT recommended for use in some metal applications such as engines or metal pipes/lines such as your air conditioners or anything containing copper and brass like heat exchangers, oil coolers, pumps, t-stats, seals, sea cocks, check valves, regulators, etc.

If I'm going to have a product sitting in these systems and hardware for 6 months, I prefer using the product specifically designed/rated/safe for them. People see pink and they figure it's all the same so they simply go through the sales flyers waiting for the best price. It is not the same stuff to be used in all systems nor is it designed to be, that's why it's cheaper.

For me as a quick check, I look for antifreeze that does not have the flammable label on the bottle as this is an indication of the presence of alcohol .....then check further.

I should also mention that most cheap plumbing antifreeze contains less PG and more alcohol (cheaper). The problem with alcohol is that it evaporates quickly, so one of the key ingredients used for protection after a while loses it's ability to protect and the rating you thought you had to begin with is reduced. All the more reason to ensure you drain all the water first to minimize dilution. It's concern enough with the expensive antifreeze let alone the cheaper stuff.

oh, you bet me to it bud37

Viper wrote:Source of the post I should also mention that most cheap plumbing antifreeze contains less PG and more alcohol (cheaper).

I have not noticed this but will check them out. I would think if they're used in potable water systems that they could not be ethyl alcohol, right? On the West Marine website they do note " our Seafit brand -50°F Marine and RV Water System Antifreeze, which is a propylene glycol/alcohol blend. This is fine for potable water and sanitation systems, but is not recommended for winter engine storage,"

My discussion with them was about the various 'grades' of polypropylene. The pink one they said is for potable and the purple is for engines because it has "corrosion inhibitors"... in reality the purple is just a higher concentration of PPG.

Now, I say this with the caveat "at that time", because they could change their formulations over the years. I'm going to recheck this year because on their website they do note "Pure Oceans Engine Antifreeze and Coolant contains an additive package" so what they have now may be different than when I had that discussion with them.