Winterizing anti freeze for RW cooled engine

[Roger Long]

The yard where I used to keep my boat always sold me rather pricey Pahnol 60 antifreeze for winterizing my engine since it had anti-corrosion additives. I called Pahnol directly to see if they had a dealer in Portland and the fellow said that, for what I was doing, he would just go to Home Depot and get what they were selling.

Home Depot has Dow for about half the price which says that it has "proprietary" anti-corrosion additives". The other brands of RV antifreeze I see elsewhere just say "safe for copper, brass, and mild steel".

Seems like the Dow stuff is the way to go but, does anyone know if this is just a difference in label wording?

 

[navigator97]

Roger, I would think that the -60F at Home Depot would be OK for the raw water loop. I also use the 1st gallon as -100F antifreeze and as that is almost completely sucked up into the engine I add a 2nd gallon but of the -60F stuff. The reason for the -100F antifreezeis that a it is "chasing" the sea water out, it is being deluted and is no where near -100F any more. The temp ratings are for the antifreeze as it comes out of the jug, not after delution.. A total of 2 gallons is sufficient for my engine's raw water loop - I have a Yanmar 2GM20F engine. The above combination of antifreeze was recommended by the foreman at our marina. I did the winterizing of the engine myself.

 

[Roger Long]

I run fresh water through from a hose into bucket set up for 15 minutes or so to flush the salt out and then drain the engine with the petcocks provided. No need then for -110F antifreeze.

 

[alexco38]

10F isn't cold. Automotive antifreeze

If you are in Portland Maine per your avatar, you average low temp of 10F isn't that cold compare to the great white north. We gets to lower than -22F around here.

Normally you need to mix 50-50 for Automotive antifreeze. Nowadays, they have pre-mixed on the market so be careful.

Concentrated automotive anti-freeze has done the job for me for many years around here. Just let the engine suck in un-diluted antifreeze until it comes out the exhaust. The residue water inside the engine will dilute the anti-freeze.

Don't use plumbing anti-freeze as they have no rust inhibitors.

 

[Rich Stidger]

Roger,

For years I have used Sierra brand "safe" antifreeze in my raw water loop. Prestone used to make a version of this but I haven't found it in several years.

I dilute it 50/50 and after flushing the raw loop (engine sucks from a hose in a bucket) with fresh water for 10-15 minutes, I change the oil & filter and then let the engine suck in the antifreeze until it runs out. I change the oil first so that when I run the engine to pull in the antifreeze the clean oil is coated everywhere.

Many years ago with my old Atomic 4, the PO told me to simply drain the raw loop. I found that to be a mistake because rust formed inside the engine and in the Spring I had a real problem getting water to flow through the engine due to rust build-up. From that point on I always filled the cooling loop with corrosion-inhibited antifreeze.

I never had a problem in CT or RI winters with any freezing.

 

[Maine Sail]

Don't use plumbing anti-freeze as they have no rust inhibitors.

Generally speaking many of the -50F RV propylene glycol products do not have an anti-corrosion additive but some do, most notably the -60 and -100 versions and the -50 versions sold by West Marine also have the corrosion package. Usually the -60 PG or -100 PG products do have anti-corrosion additives.

You could also buy hydronic boiler antifreeze, which is PG with anti-corrosives designed for protecting hydronic heating systems. They generally come in 5 Gal buckets made by folks like Hercules Chemical and sold as Cryo-Tek, and brands like No-Burst. These products however are very expensive, nearly $20.00 gal but are -100 rated and have very, very good anti-corrosion packages as many hydronic boilers are steel not just cast iron..

You can buy -100 from Hamilton or West, with corrosion additives for around $10.00 gallon.


West Marine Pure Oceans -50° (-46°C) Marine Antifreeze provides the ultimate in cold weather and corrosion protection for drinking water systems and all engines.
Note: The burst point of PVC pipes used in most drinking water systems is about -10°F (-23°C). When winterizing water systems in regions where temperatures can fall below -10°F (-23°C), we recommend using West Marine Pure Oceans -100°F (-73°C) Marine Antifreeze.


I generally use -60 or -100 but also drain my RW side to prevent dilution.While our average temps can be 10F we also see many dips down to -10 or -20 or more so you want an antifreeze that has a burst point that can handle the temp.


If using ethylene glycol be wary of the poisonous nature of the product and the impact to the environment. Some yards have banned it's use for winterizing the RW side of engines.

 

[Johan S.]

Shouldn't matter whether it has a rust additivie or not.. When its full with whatever liquid glycol base you use there is the absense of nitrogem / oxygen in gas or ( air ) form... Iron oxide will form quickly when the water is drained, but when a liquid glycol is present it will take some time for oxide to establish regardess of rust inhibitor.. Thats why Iron canons last 100's of years underwater. Take them out and they rot away in weeks..

 

[njsail]

and don't be shy about using a couple extra gallons to winterize your engine depending on the size. I used to just watch till it runs pink and shut the engine. I learned the pink stuff needs to circulate through all the tubes/holes in the heat exchanger which might have some buildup and therefore take longer to work it's way through. It's cheap insurance compared to a new engine. I've seen a couple engines need replacing and cringe at the thought of the expense. I have a 50hp Volvo and use about 4-5 gallons. Don't forget to change the oil before you winterize this way you can warm the oil and it comes out easier.

 

[Alan]

I remove the hose from the seacock and insert it into a one gallon jug of pre-mixed global automotive anti freeze. Run the engine till the yellow liquid is present in the exhaust. By this time the gallon is gone and I'm done. Have done this for years and takes only a few minutes and one gallon to complete. I have a Yanmar 3GM30F engine.

 

[Don Crowther]

Ok
Maybe I'm mistaken or not just getting it but isn't the 3gm a closed system and the rw goes though the heat exchanger then into the elbow? So you aren't really protecting your engine but just your rw side. Your engine anti-freeze is in the overflow res. isn't it? This should be running with a 50/50 mix of anti-freeze and water.

 

[Maine Sail]

Ok
Maybe I'm mistaken or not just getting it but isn't the 3gm a closed system and the rw goes though the heat exchanger then into the elbow? So you aren't really protecting your engine but just your rw side. Your engine anti-freeze is in the overflow res. isn't it? This should be running with a 50/50 mix of anti-freeze and water.

I am fairly certain Roger's engine lacks the "F" designation as in 3-GM-F. His is RW cooled not fresh with an HX.

 

[Roger Long]

I am fairly certain Roger's engine ... is RW cooled.

Correct. If I ever buy another engine, it will be fresh water cooled so I can make hot water but, in the meantime, I'm appreciating the great simplicity of RW cooling. There are a lot of things that can go wrong or leak in a FW system that leave you overheating. As long as water goes through my engine, it stays cool. One pump instead of two. Since the engine was in fresh water until I got the boat, it will probably last longer than I will.

 

[Don Crowther]

Sorry. I thought all 3 gm's were all like mine. I'll go back to sleep now

 

[rpwillia]

Two THings

...just watch till it runs pink ... Don't forget to change the oil before you winterize this way you can warm the oil and it comes out easier.

I have heard you should change the oil in your car as all the stuff you are changing it for is floating in the oil in the pan when it is cold. It is easier to change hot, but don't we want to get rid of all the stuff suspended in the oil which is more important?

I have been using the pink stuff that is designed for the drinking water system and not automotive anti-freeze (which except for the green stuff is toxic) and just using it straight with no mixing (not shaken, not stirred).

I also open all my through hulls (sinks) and pour the pink stuff in, let it drain for a second and then shut them leaving the pink stuff in.

 

[Blitz]

Jut drain the system?

Generally speaking many of the -50F RV propylene glycol products do not have an anti-corrosion additive but some do, most notably the -60 and -100 versions and the -50 versions sold by West Marine also have the corrosion package. Usually the -60 PG or -100 PG products do have anti-corrosion additives.

You can buy -100 from Hamilton or West, with corrosion additives for around $10.00 gallon.

I generally use -60 or -100 but also drain my RW side to prevent dilution.While our average temps can be 10F we also see many dips down to -10 or -20 or more so you want an antifreeze that has a burst point that can handle the temp.

Would there be any advantage of draining the system (as my old Yanmar manual instructs)?
Do you lose all the anti-corrosion advantages? I did this the last two years but question the sanity of basically adding -60 or -100 type antifreeze only to drain it - but my thought was that if there was any dilution I would be safer by draining the engine and lift muffler. Thoughts?

 

[Roger Long]

I did this the last two years but question the sanity ...

I think you have it backwards. You drain first to avoid dilution. Then you put the antifreeze in and leave it to prevent corrosion.

 

[tommays]

I am one of those crazy people with a RW motor in my trailer powerboat which gets flushed with freshwater after every use and your NOT gonna poor in anti-freeze every week

It has suffered no ill efects over a 16 year time frame and i will post a picture of the water passages from when i pulled the elbow becasue of the false fear of corrision

 

[LordNelson]

i don't use any antifreeze on my power boat. i just pull the drain plugs on the block and exhaust jackets, and drain the hoses. i have never had a problem and the boat has gone through 19 ny winters.