How much is enough?

[RON20406]

In a recent boatyard discussion, winterizing engines was discussed. If you have a fresh water cooled diesel( 2 or 3 cylinder), how much antifreeze is needed for the raw water side after you have drained the water muffler and sea strainer? I will be non-commital since a wager is involved. Best, Ron

 

[petersea]

Enough that anti freeze is coming out the exhaust,will depend on muffler size and hose length but in most cases one to two gallons is enough. Pour in the strainer until (assuming you are using pink type) until it is same color.

 

[Warren Milberg]

I have a Yanmar 2GM20F and I don't bother draining the waterlift muffler when winterizing. I simply take off the hose to the water strainer, connect a piece of hose to the barb, and put the other end of the hose in a pail with ONE gal of purple antifreeze and run the engine until it's sucked up. That's all it takes.

FWIW, I would not try to save a few bucks, particularly in a very cold climate, by using the pink RV antifreeze. Use the -100 deg purple stuff.

 

[RON20406]

I always drain my wet exhaust and sea strainer before decommisioning my engine for storage. I do this to remove any sediment in the bottom of the wet exhaust/sea strainer that might not be removed during normal operation. I then flush 1 gallon of pink (-30/-40) and one gallon of purple (-60/-100) before shutting it down. This is more than sufficient to properly safeguard your raw water intake/engine/exhaust for long term Winter storage. Anything more is unnecessary. And, by the way, thanks Pete and Warren for your responses since I will be enjoying a bottle of Glenlivet tonight accompanied by Wagner's "Ride of the Valkyries!" Good luck and good sailing, Ron

 

[Maine Sail]

There is no one answer. The ONLY answer is however much it takes so that what is coming out the exhaust still has a burst & freeze temp of what it went in with. I use test strips or a tester so I know what it takes on my boat. Every boat will be different depending upon hose lengths, HX capacity and impeller condition.

PG should not be diluted, remember that is the burst point, not the freeze point, that matters and draining the strainer and muffler will help you use less to keep the dilution to a minimum.

I have seen many engines/HX's that have frozen due to dilution. Some boats also have engine driven refrigeration with a huge HX that can be well over a gallon... The safest bet if you want to use minimal AF is to use a -100 that can be diluted a little before issues happen.

The only way to settle your bet is with an AF tester by catching it in a bucket at the exhaust.

Basically none of the PG stuff should be diluted. The -50, -60 & -100 are all general guides for undiluted burst points and they are not set in stone or standardized tested freeze or burst points.

-50 for example contains only about 30% by volume, propylene glycol. Reducing that concentration, through dilution (the water already in the raw water loop), to just 12.5 percent PG by volume, raises the BURST POINT to about 20 F which is a far cry for -50 @ 30% PG by volume. In this example you can see that just a little dilution raised the burst point by 70f!!!

As you're doing, it is a good idea to drain the raw water side first or just use more antifreeze so you know it is not diluted. My raw water side can hold over two gallons of raw water between the strainer, hoses, HX, water-lift muffler and my refrigeration heat exchanger. This could mean major dilution and in Maine that is not a good idea.. This is why I drain it first before sucking in the -60f or -100f PG and then test it.

If you read the label on -60 for example it says copper pipes may burst at -60F but that plastic is only protected to -26F and this is undiluted. HX tubes are very, very thin copper and are probably more fragile than PVC..