Do Any of You Freshwater Flush Your Engine?

[Comodave]

Oh, you use soap when you shower…

 

[Arc]

Try not to used brass when you build these systems.

 

[Simi 60]

Well, historians have pulled bronze artifacts in good condition dating back 1600 years from salt water so I'm guessing a fresh water flush is not needed.

https://www.smithsonianmag.com/smar...nze-artifacts-israel-national-park-180959143/

 

[rslifkin]

Well, historians have pulled bronze artifacts in good condition dating back 1600 years from salt water so I'm guessing a fresh water flush is not needed.

https://www.smithsonianmag.com/smar...nze-artifacts-israel-national-park-180959143/

Not so much needed for bronze parts, but plenty of engines do have lesser materials (like cast iron exhaust elbows) in the raw water circuit. Flushing will at least somewhat extend the life of those parts. Probably helps keep salt deposits and such in the heat exchanger down as well.



When I first brought my boat into fresh water, after it sat for the first night in fresh, it blew a whole lot of junk out of the exhausts on startup the next day. And the engines ran a couple degrees cooler on plane after that, so I'm figuring it was salt buildup or similar junk in the heat exchangers dissolving.

 

[Art]

Simply put: Freshwater is kinder to metal parts than is saltwater.

Regarding freshwater flushing engine each time used in salt water:

Welllll... back in the 50's / 60's / and even into the early 70's on east coast... a whole lot of boats ran in saltwater with RWC engines... usually there were not heat exchangers, antifreeze coolant mix etc; such as currently prevalent. And - I was always around marinas... worked in a couple too. Long and short of it: As I clearly recall, seldom was a boat motor's demise due to RWC. But rather because of many hours use or ongoing incorrect too high rpm use or non conducted maintenance.

I'm not saying that freshwater flush each time engine is run in saltwater is not at very least somewhat of a helpful preventative measure to extend time till eventual demise of the engine [and specific engine parts]. What I am saying... is for me to each time after starting engine in saltwater then needing to flush with freshwater had better be a really simple "fasten the hose to easily accessible connection area" on side of hull... and ... flick of a button to accomplish the flush-out while i tend to other items. Because - being a pretty busy fellow I do not want to have just one more 30 to 45 minute chore befor leaving the boat in its slip.

There's a trade off for everything in boating!

 

[backinblue]

There's something I brought up in an earlier post that I think deserves consideration and I'm interested in some TF opinions. Assuming your engine anodes are zinc and not aluminum for the moment. If you always freshwater flush your engine, then the zinc sits in freshwater until you use the boat again. This can build up a coating on zinc and render it useless. Then you no longer have anode protection internal to your engine. Couldn't that condition be potentially more damaging to your engine than the salt water? Obviously you should use Aluminum if you are doing a fresh water flush or running in fresh water for periods of time, but not everyone does that. My point being the fresh water flush could be doing more harm than good.

 

[Comodave]

There's something I brought up in an earlier post that I think deserves consideration and I'm interested in some TF opinions. Assuming your engine anodes are zinc and not aluminum for the moment. If you always freshwater flush your engine, then the zinc sits in freshwater until you use the boat again. This can build up a coating on zinc and render it useless. Then you no longer have anode protection internal to your engine. Couldn't that condition be potentially more damaging to your engine than the salt water? Obviously you should use Aluminum if you are doing a fresh water flush or running in fresh water for periods of time, but not everyone does that. My point being the fresh water flush could be doing more harm than good.

No, no, no! Just use aluminum anodes. They are fine in ALL types of water. Get rid of the zinc anodes. And the aluminum anodes are better for the environment.

 

[backinblue]

No, no, no! Just use aluminum anodes. They are fine in ALL types of water. Get rid of the zinc anodes. And the aluminum anodes are better for the environment.

I don't disagree Dave. But my point is that some people are doing a fresh water flush with zinc anodes, so I'm questioning is that doing more harm than good in the long run. (See posts #5 and #20)

 

[Comodave]

Then they should replace the zinc anodes with aluminum. That is just common sense. You should not use zinc anodes in fresh water. I know some do but they shouldn’t. They will say that their anodes last a long time, and yes that is likely true but you don’t want your anodes lasting a long time. They last a long time because they aren’t working so some other metal is acting as the anode. I have heard this argument for years and it is sometimes difficult to encourage people to give up zinc anodes “because mine are working and they last a really long time “. That in itself is saying contrary things.

 

[Skiff Builder]

I don't disagree Dave. But my point is that some people are doing a fresh water flush with zinc anodes, so I'm questioning is that doing more harm than good in the long run. (See posts #5 and #20)

For myself, I would be doing a 5-10 min freshwater flush after a full day of salt water running. I don't see zinc skinning over with that short a time.

I'll be running 3 days in tidal water, than 4 months fresh water before getting to the Gulf. At that time it sounds as if I should switch to Al anodes for the remainder of the Loop.

 

[Comodave]

For myself, I would be doing a 5-10 min freshwater flush after a full day of salt water running. I don't see zinc skinning over with that short a time.

I'll be running 3 days in tidal water, than 4 months fresh water before getting to the Gulf. At that time it sounds as if I should switch to Al anodes for the remainder of the Loop.

But it isn’t just 5 or 10 minutes, the freshwater will sit in the engine until you run it the next time. There isn’t any legitimate reason not to use aluminum anodes all the time. Why wait until later?

 

[Art]

This whole thing about aluminum anode only and flush your engine after each saltwater use... reminds me of the over yelping of - You should wear masks everywhere!

Seeing as for many, many decades boat owners got along pretty much OK via scheduled maintenance... well, just saying!

 

[Mako]

This thread makes me yearn for a keel cooled boat with dry exhaust

 

[backinblue]

For myself, I would be doing a 5-10 min freshwater flush after a full day of salt water running. I don't see zinc skinning over with that short a time.

I'll be running 3 days in tidal water, than 4 months fresh water before getting to the Gulf. At that time it sounds as if I should switch to Al anodes for the remainder of the Loop.

I think you or perhaps me are missing something. If you flush with fresh water then leave the boat for a week, are the zincs not sitting in fresh water for a week till you run the boat again in salt water?

 

[Comodave]

I think you or perhaps me are missing something. If you flush with fresh water then leave the boat for a week, are the zincs not sitting in fresh water for a week till you run the boat again in salt water?

Yes, they are.

 

[backinblue]

Yes, they are.

See? I told you not everyone get's it!

 

[backinblue]

This whole thing about aluminum anode only and flush your engine after each saltwater use... reminds me of the over yelping of - You should wear masks everywhere!

Seeing as for many, many decades boat owners got along pretty much OK via scheduled maintenance... well, just saying!

I agree with you Art and I don't flush my engine, but it is in a tidal river so does get some fresh/brackish water each to and from my home dock. But what I am finding amusing is that there are obviously some boaters here that are flushing but not using Al anodes so they are flushing out salt but also defeating the engine Zn's at the same time which is probably worse for the engine in the long run than if they did nothing at all!

 

[firehoser75]

I agree with you Art and I don't flush my engine, but it is in a tidal river so does get some fresh/brackish water each to and from my home dock. But what I am finding amusing is that there are obviously some boaters here that are flushing but not using Al anodes so they are flushing out salt but also defeating the engine Zn's at the same time which is probably worse for the engine in the long run than if they did nothing at all!

It is possible that freshwater flushing while still using zinc anodes, and leaving the engine to sit full of freshwater could be worse than not flushing (if the zincs stop doing their job and other metals "take their place"). Therefore, switch to aluminum engine anodes as Dave said. Easy, peasey.

However, besides other benefits, FW flushing reduces and may almost eliminate the build up of salt/calcium deposits in the various heat exchanger internal tubes. Having clean(er) tubes will reduce the engine operating temperature by improving the HX efficiency compared to a blocked or partially blocked HX. Engine speced operating temps are "brand new" with clean tubes. Having an engine overheat, especially if the boater is relying on the "stock temp alarms" to notify them, could easily lead to serious (and expensive) engine damage!! It has been known to happen. The only downsides to FW flushing are: it takes about 10 minutes (or less) of your time (each time but it is easy to do); and you need to switch to aluminum engine anodes (instead of zinc). And the cost ($) is close to zero.

Preventive maintenance isn't mandatory, and neither is FW flushing, but both are "good ideas" that have proven track records (IMHO).

Edit: For those who moor in freshwater or brackish water, this is all moot (except the part about the aluminum anodes).

 

[Comodave]

I really don’t understand the thinking of people that still insist on using zinc anodes. When aluminum will work everywhere. Sorry, I just don’t get it…

 

[Art]

I really don’t understand the thinking of people that still insist on using zinc anodes. When aluminum will work everywhere. Sorry, I just don’t get it…

Why? For many, many decades zinc and magnesium were the standard for use as anodes? Then, suddenly... the boating world decided that aluminum is the best anode... as compared to all others?

Aluminum as an anode has been available, but off to the side, for years. Was it that there now is a better mixture of other items to add to aluminum that increased its anode capabilities? Were there simply not enough scientific tests accomplished before hand?

In other words - What Gives???? To suddenly make aluminum the King of anode material that is to be used at all times, on all marine metal portions, in all waters?

I am confused!!

 

[backinblue]

I'm kind of coming over to the Al side, however there are lots of boater like Art who have always used Zn and don't see the need to change. Change takes time and is not easy. I have some boating friends that have been boating for 50 years and never even heard of Al anodes.

 

[Comodave]

Just because they have always done it one way doesn’t necessarily make it the best way. Maybe there have been advancements in the last 50 years or so??? I think so. However if you do freshwater flushes you shouldn’t use zinc as an anode. But if you don’t believe me that is ok. Go ahead and use what you want to. It isn’t my boat that isn’t being protected as well as it could be. Either way I am done trying to convince them.

 

[Art]

Irrespective regarding the freshwater flush topic; which is pretty much a different subject than various metal materials' anode quality...

And, not at all saying that aluminum isn't necessarily a very good anode material.

What I'm trying to figure out, is: Why suddenly [within the last few years] did aluminum become King Anode in boat owner conversations. So far anecdotes rule the posts. I've not seen scientific research results on the quality of aluminum compared to other anode materials.

I have no problem to use the best anode material... in what ever metal is proven to be the best. But, not simply by anecdotes posted on forums.

 

[Skiff Builder]

Originally Posted by backinblue View Post
I think you or perhaps me are missing something. If you flush with fresh water then leave the boat for a week, are the zincs not sitting in fresh water for a week till you run the boat again in salt water?

QUOTE=Comodave;1109659]Yes, they are.[/QUOTE]

See? I told you not everyone get's it!


Ok Commodave and Backinblue, I think I now understand your Al/ Zn flushing points.
This is my first fresh water cooled boat, owned for a month- that's why I posted the question here. Thanks for the info appreciated with or without the sarcasm!

Somehow I've managed to keep my 3 raw water cooled engines running for almost 30 years each in the briney. Aiming for same with new boat.

 

[backinblue]

Sorry Skiff, no srcasm was intended, but was just trying to keep this from turning into a heated argument. Personally, I am switching to Al, not because I flush the engine, but because my boat sits in a river that can be salt/fresh/brackish depending on the weather and tide. If I was 100% in salt water all the time, not sure I would rush to change. Zincs are just more common and readilly available, especially for engines and and anything less common. Not that you can't find them, just that they may be less likely to be in stock at your local marine store. Keep in mind that all anodes connected to the same bonding system have to be of the same material. That said, SidePower has switched to Al for 100% of their anodes. Thruster and Engine anodes are not part of the bonding system so they can be different.

 

[Hippocampus]

The Al alloy used for anodes is quite different than that used for other applications. It isn’t that noble so does sacrifice just about as well as Zn. Fresh water is less conducive than salt so anodes generally last a bit longer in fresh. Biosphere in fresh is different than that in salt with only some overlap. Switching back and forth means the salt intolerant organisms will die when in salt and the fresh intolerant in salt. So if you switch back and forth less growth. Some suggest not flushing every time but rather only if boat isn’t to be used for at least a few days to make use of variance. Stuff doesn’t grow in a hot heat exchanger. Does in intake hoses and when HE are cold.

 

[Art]

The Al alloy used for anodes is quite different than that used for other applications. It isn’t that noble so does sacrifice just about as well as Zn. Fresh water is less conducive than salt so anodes generally last a bit longer in fresh. Biosphere in fresh is different than that in salt with only some overlap. Switching back and forth means the salt intolerant organisms will die when in salt and the fresh intolerant in salt. So if you switch back and forth less growth. Some suggest not flushing every time but rather only if boat isn’t to be used for at least a few days to make use of variance. Stuff doesn’t grow in a hot heat exchanger. Does in intake hoses and when HE are cold.

"Stuff doesn’t grow in a hot heat exchanger." "Does... when HE are cold"

However, heat exchanger is hot to begin with. "Stuff" [for the growths] must live through the 160 to 200 degree f heat?

But, then again... maybe the RW that had been flowing through to cool the coolant mix never reaches that high a temp when engine is shut down for no more RW flow. MOF... even while running at full temp the RW flowing through HE probably never gets much above 110 degrees f.

By thinking things through I often can answer my own questions! And, wife wonders why I talk to myself so often... LOL

 

[Comodave]

I don’t think the main reason for freshwater flushing is to kill organisms, but rather to remove the salt water and the corrosion associated with the salt.

 

[Art]

I don’t think the main reason for freshwater flushing is to kill organisms, but rather to remove the salt water and the corrosion associated with the salt.

Can saltwater organisms live/thrive in freshwater... at all?? And, vice versa I guess?

 

[Comodave]

Can saltwater organisms live/thrive in freshwater... at all?? And, vice versa I guess?

I have no idea…