Engine Impeller and Anti Freeze

[tsd]

I read somewhere (if it's on the internet it must be true), that if you use the raw water impeller to get antifreeze into the engine, the impeller needs to be replaced in the spring.

Is this true?

Yanmar SB8 diesel, if that affects the answer...

[thinwater]

Originally Posted by tsd

I read somewhere (if it's on the internet it must be true), that if you use the raw water impeller to get antifreeze into the engine, the impeller needs to be replaced in the spring.

Is this true?

Yanmar SB8 diesel, if that affects the answer...

It depends on the impeller material and the type of AF.

If the impeller is nitrile, it probably does not matter.

If the impeller is neoprene (much more common for cooling), neoprene is incomparable with propylene glycol (potable water type) antifreeze. Ethylene glycol (automotive AF type) is not a problem.

Since it is not potable water system, just use automotive AF. This is also true of the head (neoprene parts), which is also (last time I checked ) not potable.

You can confirm this general rule on any materials compatibility chart. Funny the manual does not point this out.

[sailorchic34]

Originally Posted by tsd

I read somewhere (if it's on the internet it must be true), that if you use the raw water impeller to get antifreeze into the engine, the impeller needs to be replaced in the spring.

Is this true?

Yanmar SB8 diesel, if that affects the answer...

Generally it does not harm the impeller at all and it's good for keeping the pump from freezing too.

[tsd]

I don't remember the type I used, it was what they had the marina, which was environmentally safe. I'm guessing propylene. So it sounds like it may not mix well? Maybe have a spare with gasket on board?
Luckily it's very accessible.

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[Scaramanga F25]

We use it every year winterizing in Canada. Not been a problem on 4 different makes.

[Scaramanga F25]

We use it every year winterizing in Canada. Not been a problem on 4 different makes. Some remove the impeller after so that it doesn't take a set shape.

[thinwater]

Originally Posted by tsd

I don't remember the type I used, it was what they had the marina, which was environmentally safe. I'm guessing propylene. So it sounds like it may not mix well? Maybe have a spare with gasket on board?
Luckily it's very accessible.

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a. Yes, that was PG.

b. There is no difference in environmental harm between EG and PG. Both have equivalent, very low marine toxicity and both are equally biodegradeable, and both have very high BOD5. PG is toxic to mammals, but that is the only difference. The rest is urban legend.

[Pendragon35]

Originally Posted by thinwater

a. Yes, that was PG.

b. There is no difference in environmental harm between EG and PG. Both have equivalent, very low marine toxicity and both are equally biodegradeable, and both have very high BOD5. PG is toxic to mammals, but that is the only difference. The rest is urban legend.

Thanks for this. I replace the impeller in the spring as a good luck charm and keep the old one for a spare. There's nothing quite like coming into Baltimore's inner harbor with a tub coming on, a cargo carrier and power boats everywhere and suddenly having the impeller go out and the engine have to be stopped. Far worse than the cost of an impeller.

[hamburking]

Originally Posted by tsd

I read somewhere (if it's on the internet it must be true), that if you use the raw water impeller to get antifreeze into the engine, the impeller needs to be replaced in the spring.

Is this true?

Yanmar SB8 diesel, if that affects the answer...

NO, not true.

[grae]

Originally Posted by Pendragon35

Thanks for this. I replace the impeller in the spring as a good luck charm and keep the old one for a spare. There's nothing quite like coming into Baltimore's inner harbor with a tub coming on, a cargo carrier and power boats everywhere and suddenly having the impeller go out and the engine have to be stopped. Far worse than the cost of an impeller.

You and me both Pendragon35 - I also swap out every spring, for the potential downsides and the relative cheap cost of the impeller I figure it's a cheap piece of insurance, but generally agree there is no actual 'need' unless you have damaged fins.

I also was under the impression that AF caused the rubber to swell, but I guess that was myth so thanks for clearing that little one up!

G

[thinwater]

Originally Posted by grae

You and me both Pendragon35 - I also swap out every spring, for the potential downsides and the relative cheap cost of the impeller I figure it's a cheap piece of insurance, but generally agree there is no actual 'need' unless you have damaged fins.

I also was under the impression that AF caused the rubber to swell, but I guess that was myth so thanks for clearing that little one up!

G

Actually, PG makes it get stiff. It is not always fatal, just another factor.

It has no affect on nitrile impellers, which may account for some of the difference in experiences.

[wesevans]

It is good maintenance practice to replace your raw water pump impeller every year weather you have run the engine or not.

[Stu Jackson]

My engine, Universal M25, uses a metal impeller, with the raw water pump having a flexible one.

Do Yanmars have plastic impellers for the coolant pumps?

[tsd]

I think they do. I haven't opened it up yet to get a look, but I have a new one and gasket on order. We're putting in soon for the season!!

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