Winterizing Yanmars in Beneteaus

Greetings all. Have been lurking for some time. This is my first post here. There was a great post here on winterizing a Swift trawler with lots of good info.
I have a few questions soley about the engine raw water system winterizing process. I always like to check the discharge from the exhaust with a refractometer but an underwater exhaust makes that impossible.
1. The 6 cyl yanmars have 5 gal cooling system so I am guessing it would take a minimum of 6 gal to get full concentration. How many gals are folks using?
2. To check the concentration is correct after flushing, where is the best place to take a sample? Ie the heat exchanger?
3. How are people feeding the antifreeze into the engine? The plastic vetus strainer will not take a Sea Flush and the 1 3/4 inch hose must be a bear to remove and flex into a bucket of antifreeze. Pouring antifreeze into the strainer had been suggested but doing that next to a running engine fast enough and without interupption I think would be very difficult. I like the idea of installing a tee but what type and diameter hose will work?
Thank you.

Not the same engines, but my strainers feed from the bottom, so I just pour antifreeze into them (with the tops off and seacocks closed). Even at idle it's not possible to pour quite fast enough (even with crushing the bottles to get the liquid out faster) and it's a game of lining up bottles before start and then cleaning up the empties thrown all over the place after shutdown (mine take 8 - 9 gallons to get a good concentration all the way through the big waterlift mufflers, etc.).

Antifreeze is slippery, so even if it's sucking some air along with the antifreeze it won't kill an impeller. But if you have a weak impeller, it may airlock and then it's usually impeller change time.

You could also put a tee fitting into the line coming from the strainer to allow you to feed antifreeze in from a bucket or pump at that point in the system.

I suspect that you are talking about one of the Yanmar 6LY models, right? I am surprised you say the raw water system holds 5 gallons. Ours would show bright pink after flushing 3 gallons through so I used 4 gallons.

Pouring antifreeze into the top of the strainer is easy. Just line up 4 gallons of open containers, shut off the thru hull, start the engine and start pouring. Takes about a minute to suck up 4 gallons.

You can check the antifreeze concentration by opening the zinc fitting on the bottom of the lube oil cooler (starboard side, forward end of cooler) and catching a sample. That is near the end of the r/w cooling path.

David

When you say a 5 gallon cooling system, is that the "fresh water" side of the system? In other words, the side with the anti-freeze engine coolant in it? That generally will be the only "cooling system" referenced as having a certain capacity.

You do not winterize that side, only assure proper anti freeze concentration. Its the raw water side that must be winterized.

Ken

More then half of the winterizing will drain out. 5 gal is fine

Thank you all for all the replies. Yanmar lists the capacity as about 21 qrts, understand that is the fresh water closed loop but I guess the raw water side must be at least as much.
For my prior 3 cyl Universal with 2 qrts capacity it was easy to just stick a hose in a 5 gal bucket and pull the antifreeze thru. The thought of trying to pour 21 plus qrts in fast enough with the engine running makes me nervous but your experiences shows it can be done.

A couple of more points:

The coolant side volume is not equal to the raw water side. The r/w side is inside tubes whereas the coolant side is outside the tubes or the "shell side" as the engineers call it. The shell side is probably 50% more than the tube side volume, not to mention the engine water jacket which doesn't affect tube side volume. OTOH you have the tubeside volume of the gear, air and lube oil cooler to add to the r/w volume. So they are hardly related. All in all I do believe that the r/w side is about 3 gallons.

You don't need to pour antifreeze continuously. You can stop 10 seconds between each gallon and more when you need to shut off the engine. The antifreeze is a great lubricant so it keeps the impeller moist even though there is no fluid being pumped in between containers of antifreeze. But do have the containers standing by opened.

Finally I have done this for several winters with a 6LY and never used more than 4 gallons of antifreeze. But hey, 6 can't hurt.

David

We have fittings on a seacocks, makes for easy switching to winterize, we use 5 gallons of the pink stuff, 3 for the gen.

Thank you Dave for your helpful thourghness.
Mike do you have any pics of your set up?