Fresh Water Flush Your Engines?

[Taras]

Hi All,
About 3 years ago I installed a fresh water flush system for all of my engines ( 2 mains and 2 gen sets).
What I did was to tap into the top of the sea strainer, screwed in valve and then ran a fresh water hose to the top of each of the 4 sea strainers.* Now when I am done with a cruise, I simply shut off the sea valve, turn on the fresh water and let the engines run for a few minutes to fully flush the engines raw water system.
After doing this for 3 years, I have not had to replace any*the numerous engine zincs or worry about having to boil out the heat exchangers.

After watching my friend spend a lot of money on replacing his heat exchangers due to corrosion, I just wonder why they don't make this standard equipment on salt water vessels?

Does anyone else have a fresh water flush system?

Steve

 

[Forkliftt]

Steve-
I don't, but I sure like your idea. I try to rinse my dink engine in fresh water when we get to the slip- why not the rest. Do you have Groco sea strainers? Any pics?

 

[Jay N]

Taras wrote:

Hi All,
About 3 years ago I installed a fresh water flush system for all of my engines.* After doing this for 3 years, I have not had to replace any*the numerous engine zincs or worry about having to boil out the heat exchangers.

After watching my friend spend a lot of money on replacing his heat exchangers due to corrosion, I just wonder why they don't make this standard equipment on salt water vessels?

Does anyone else have a fresh water flush system?

Steve

Can vouch for a fresh water flush system greatly extending zinc/heat exchanger maintenance/service life.*

Installed the first one on my wooden 40' Ed Monk Sr. classic after repowering in 1980.* Sold that boat in 1997 without any cooling system issues.

Bought the current boat in 1997, and could see there had been salt water corrosion in the cooling systems of both the ME and genset.* For the ME, as you did, I drilled*a hole in the raw water stainer and mounted a valve and hose connection.* For this application, it is very easy to bring the hose to the strainer after washing the boat, so did not have to run any internal FW supply.

For the generator which is located near the fresh water tanks, I tapped in to the cooling line between the thru-hull and strainer, the FW supply comes unpressurized from the fresh water tanks.* This setup allows me to easily drain the FW tanks by running the generator which provides regular turn over of fresh water.

It is difficult to quantify the level of improvement to the cooling systems by installing a FW flush, but I would guess that it easily extends most maintenance chores by 2-3 times.* Of course, a lot of this depends on how much the boat is used/tied up, along with consideration of moorage in fresh or brackish water.

I'm not aware of any production boats that come with*a FW flush.* It's a great owner add-on.

 

[FF]

"Can vouch for a fresh water flush system greatly extending zinc/heat exchanger maintenance/service life. "


It extends the ZINC life because in fresh water zinc is not effective.


Save the zinc , loose the heat exchanger?

Magnesium is the protection in fresh water , in the engine or on the hull.

 

[Nomad Willy]

Hi David,
I finally joined boatdiesel but have'nt been there much yet.
How long do most heat exchangers last?
One shouldn't run the fresh water hose very long without running the engine as the lift mufflers can fill up and flood the engine through the exhaust valves.

 

[Jay N]

FF wrote:

"Can vouch for a fresh water flush system greatly extending zinc/heat exchanger maintenance/service life. "


It extends the ZINC life because in fresh water zinc is not effective.


Save the zinc , loose the heat exchanger?

Magnesium is the protection in fresh water , in the engine or on the hull.

In my current engine, the heat exchanger zinc*does not remain immersed after the engine is shut down.* The zinc is replaced based on engine hours.* But I observe less salt water effect/corrosion on the sea water pump which remains immersed in FW.* The engine remains bonded to the underwater zincs.

*

 

[Jay N]

nomadwilly wrote:

One shouldn't run the fresh water hose very long without running the engine as the lift mufflers can fill up and flood the engine through the exhaust valves.

Eric,* forgot to mention that I run the engine while flushing.* But I don't have a lift muffler, so could theoretically flush with using only FW system water pressure.* But at my moorage, water pressure is very high, and it has to push past the sea water pump.*

So the best solution for my application is to run the engine for a few minutes while flushing.* I leave the thru-hull valve open, so the cooling system does not become pressurized.* The fresh water supply is greater than the supply needed for the engine to run at idle, so everything ends up being fresh water.

*

 

[FF]

"Fresh water is much less corrosive with or without zincs or magnesium anodes and zincs do some good in fresh water, but not as good as magnesium."


The Zinc is to slow down Electrolisis , not sludge , or salt corrosion on metal.

 

[Andy G]

What is boatdiesel?

 

[Taras]

FF,
You are more knowledgeable about this topic than me, but I have owned Fresh Water boats my whole life and have never had any corrosion issues with any of them.*

By fresh water flushing the*engines of the salt water vessel I have now, I have been able to avoid replacing the large number of zincs on my engines and have been able to avoid over heating issues with the heat exchanger.* With all the maintenance on a boat, this is one less thing I have to worry about.* I am very pleased with what Fresh Water flushing has provided.

Steve

 

[FF]

but I have owned Fresh Water boats my whole life and have never had any corrosion issues with any of them.

Perhaps the dockside power was in better condition , or the past boats electrics were better done?

Electric dumped in Fresh water can kill, people or gear , just as sea water can.

 

[timjet]

I installed a fresh water flush after purchasing my boat last May. I never used it because it is docked in fresh water. I finally had a chance to use it this last weekend as we moved the boat to a salt water location. Shortly after the purchase I had to change the raw water pump on the port engine.

Last weekend as I was flushing the engine my routine is to hook up the hose to the top of the strainer but not turn it on. I start the engine and then turn on the hose. I then slowly close the engine thru hull valve and flush the engine. I did the stbd engine first and it worked perfectly. Ran the flush for about 5 minutes.


Did the port engine in the same manner, got it started and went to the bridge to check on something else. Came back 2 minutes later and found the hose leading to the strainer collapsed and thus very little water getting to the engine. I immediately shut the engine down and turned the water off, with hopefully no damage to the impeller.


What happened is the port engine with the new raw water pump is pulling more water that the hose can supply, so it collapsed. The fix is to find a hose that doesn't collapse and to never take my eye off the hose as the engine is running.


I think Tony on boatdiesel.com has said the single most important thing you can do to extend the life of your engine is to install a fresh water flush and to ensure that it is not overpropped.


Done

 

[Marin]

timjet wrote:

*
I think Tony on boatdiesel.com has said the single most important thing you can do to extend the life of your engine is to install a fresh water flush and to ensure that it is not overpropped.

If your engine is cooled by it's own supply of coolant (anti-freeze) and that's the only thing that circulates through the engine, how does flushing the raw water system with fresh water extend the life of the engine?* I can see that perhaps it extends the life of the lube oil, transmission fluid, and engine coolant heat exchangers and the exhaust components that have raw water pumped through them, but how will it affect the engine itself?

If one has raw water cooled engines where salt water is pumped into the boat, through the actual engine*block and head**and out with the exhaust I can see it.* But I don't see how installing a fresh water flush on our boat with its*closed-loop engine cooling using diesel engine coolant (Cat brand*in our case)*would make one iota of difference to the life of our diesels.

*


-- Edited by Marin on Wednesday 23rd of February 2011 07:02:26 PM

 

[Codger2]

Marin wrote:I can see that perhaps it extends the life of the lube oil, transmission fluid, and engine coolant heat exchangers and the exhaust components that have raw water pumped through them, but how will it affect the engine itself?

Whew! I don't feel so stupid afterall. My thoughts exactly.

*

 

[Jay N]

timjet wrote:

*I think Tony on boatdiesel.com has said the single most important thing you can do to extend the life of your engine is to install a fresh water flush and to ensure that it is not overpropped.

Perhaps taken out of context, I think that Tony was talking about*hard run engines where heat exchangers/sea water cooling systems play a critical role in engine service life.**Fresh water flush helps in providing relatively clean sea water cooling system components and extends needed maintenance intervals.*

BoatDiesel regularly has threads about overheated engines, mostly due to overpropping and lack of cooling system maintenance.

 

[timjet]

Marin wrote:
If your engine is cooled by it's own supply of coolant (anti-freeze) and that's the only thing that circulates through the engine, how does flushing the raw water system with fresh water extend the life of the engine?* I can see that perhaps it extends the life of the lube oil, transmission fluid, and engine coolant heat exchangers and the exhaust components that have raw water pumped through them, but how will it affect the engine itself?

I will be the first to admit that I'm no expert and I don't think I took any one's comments out of context.

Marin, what you just described, oil cooler, heat exchanger, after cooler, exhaust components, tubo and related plumbing is the cause of most of the failures associated with high output low weight diesel engines. At least cruising the Cummings forum on boatdiesel.com seems to support this.

Additionally, those folks that run these engines at near their max rpm must take much closer attention to raw water pumps, alternators, idler pulley's and anything else that spins routinely at nearly 3000 rpm perhaps much higher when you factor in the pulley ratios.

I don't see many comments on these forums related to failures of internal components like pistons, valves, crankshafts, bearings, rings and related.

But it just makes sense to flush out the raw water system. If it didn't matter why not just send raw water into the cooling chambers of the engine instead of coolant.

But your comment: If your engine is cooled by it's own supply of coolant (anti-freeze) and that's the only thing that circulates through the engine, how does flushing the raw water system with fresh water extend the life of the engine? It doesn't,* it just extends the life of all the other components for the same reason using coolant in the engine extends the life of the engine block, head and everything else that comes in contact with coolant. A turbo for a Cummins costs upward of 2K and an after cooler probably as much or more.

*


-- Edited by timjet on Thursday 24th of February 2011 09:45:43 AM

 

[timjet]

However if your engine has simply a heat exchanger and perhaps oil cooler then a fresh water flush though still an easy way to extend the life of these components would not be as important.

Don't you flush your dingy outboard?

 

[jleonard]

Don't you flush your dingy outboard

I never have as right now it sits ON the dink on davits. I flush at the end of the season only.

 

[Marin]

timjet wrote:

Don't you flush your dingy outboard?

Sure, after every cruise if we use the dinghy.* But the salt water cools the outboard's*engine block itself.* Letting an outboard sit with salt water or salt residue in the engine's cooling passages is probably not a good idea.

I dont' deny that a fresh water flush might extend the life of the raw water cooled components of a marine*diesel engine--- raw water pump, heat exchangers, and exhaust components.* But that's not extending the life of the engine, just the ancilliary hardware.* Important ancilliary hardware, no question, but all of it is usually pretty easily changed if necessary.

I just object to the implication that not running fresh water though one's raw water cooling system is going to somehow shorten the life of your engine.* It can't because there is never any salt water in the engine.* If there is one has a much larger problem than a fresh water flush will fix

 

[timjet]

Marin wrote:
I dont' deny that a fresh water flush might extend the life of the raw water cooled components of a marine*diesel engine--- raw water pump, heat exchangers, and exhaust components.* But that's not extending the life of the engine, just the ancilliary hardware.* Important ancilliary hardware, no question, but all of it is usually pretty easily changed if necessary.

Marin,

You are of the opinion that the raw water cooling portion of your power plant is not considered part of your engine. In which case flushing the raw water portion of your power plant will not extend the life of the rest of the engine.
No argument here unless raw water makes it's way into the cylinders due to a corroded after-cooler or turbo.


I will however disagree with your opinion that the raw water portion of the engine is usually pretty easily changed if necessary. Maybe pretty easy for a diesel mechanic, and very expensive for the owner.


But a normally aspirated engine without after coolers, fuel coolers, and turbo's is a very different engine.*

*

 

[Marin]

timjet wrote:

*


1.* I will however disagree with your opinion that the raw water portion of the engine is usually pretty easily changed if necessary.


2. But a normally aspirated engine without after coolers, fuel coolers, and turbo's is a very different engine.*

*

1.* That will depend on the engine.* On older ones like our FL120s all the raw water components are easily accessible and easily changed.* And not that expensive although that will depend on how a person defines expensive.* And while we have left much of our engine work like new mounts, new exhaust systems, and*new raw water pumps*to our local diesel shop, it was because*we did not have the time or inclination to do it ourselves.* All of it but the mounts is little more than*"Attach Part A to Part B using fasteners C, D, and E."

*2.* That very well may be.* We don't have those kinds of engines so have no experience with them or personal knowledge of their susceptibility to failure if their raw water systems are not flushed out with fresh water on a regular schedule.


-- Edited by Marin on Thursday 24th of February 2011 03:48:10 PM

 

[timjet]

Marin wrote:
2.* That very well may be.* We don't have those kinds of engines so have no experience with them or personal knowledge of their susceptibility to failure if their raw water systems are not flushed out with fresh water on a regular schedule.

-- Edited by Marin on Thursday 24th of February 2011 03:48:10 PM

I don't think the light weight high performance diesels are more susceptible to failure than a NA diesel if the raw water systems are not flushed. They do however require more attention because there is more machinery to deal with and it is in contact with salt water. Regular flushing simply reduces but not eliminates the long term effect of marine age on these added components.*

But I am in no way a proponent of these high performance diesels. I had a simple 3 cylinder NA Yanmar on my sailboat that required nothing except oil and impeller changes. I decided to pick up the pace when we moved to the dark side (or rather the admiral did) and the only choice are engines with a bunch of stuff hanging off the sides vastly increasing the potential for failures. I am learning to live with these engines having been scared to death by reading the many problems others have had on the boatdiesel forums. After climbing somewhat of a steep learning curve concerning these diesels I'm hoping I've avoided the most common mistakes. I've got 40 hrs under my belt and so far they've preformed flawlessly.*

*

 

[Phil Fill]

I have seen a couple of boats up to 30+ *ft. that have wrapped a tarp under the boat and filled it with fresh water, so the boat was floating in fresh water not raw water.* I thought that was a great idea?*


*
The Eagle has been moored in fresh water for 12 years and/or brackish water for 3 years. So I have not flushed the engines and the engines are natural and coolant cooled.* I have adaptors/fitting so they could be flushed. However, the DD 671, Perkins Gen set , and the DD 671exhaust system are higher than the water line, and should drain so the raw water is not in the engine, exchangers and exhaust.**

After 3 years, I had the exchanges clean/inspected and replaced the engine/exchange zincs which were in good shape.*If there is a concern than have them inspected as*its cheaper than having them fail.*

*

 

[paulinaM]

With regards to engine flushing, I read an article recently that when you go in for an oil change or basic tune-up, your mechanic may offer an engine flush. Motor flushes are among those services that are offered much more frequently than they are really needed. Source of article: The basics of an engine flush


-- Edited by paulinaM on Wednesday 1st of February 2012 03:41:41 AM

 

[Peter B]

Too true, and that does not just apply to the oil system. More likely you will be offered a coolant flush. This can also be disastrous. How's that you say? Well I once was silly enough to entrust my car to a non-franchise garage which was primarily involvedr in brakes, transmissions and clutches, but branched out into servicing, and my wife bought some vouchers sold at the door for "cheap' services. Well, when time came for a simple service, eg grease, oil, filter and brake check, I thought..."how could it hurt...what could go wrong with them just doing that..?" The answer is plenty. It cost me an engine, I kid you not.
First, without asking they put a pure synthetic oil in it - not recommended in a fairly old engine, though it was running well and not using excess oil. Also very expensive. That was bad enough, but they went even better, and compounded the error by, again without asking, (no doubt trying to impress), put flushing solution in the radiator, advising me when I picked the car up, to "drive it two weeks, then bring it in for a flush and coolant replacement". Well the flush was not done correctly, the apprentice just stuck a hose in the radiator and pulled off the bottom hose, I saw him. I found out later it should never have been done, but if done, then it needed to be a high pressure reverse flush. So, in effect, all the flushing solution did was soften and partly dissolve all the scale harmlessly coating the water jackets, and turn it into a brown sludge, which subsequently got filtered out in the radiator core. When I was driving one day a week or so later, it ruptured the header tank, overheated, and also - not immediately apparent - cracked the head. The radiator was replaced. The company involved refused to take any responsibility. Some time later, unfortunately all happening in slow motion so hard to prove, the oil pressure started falling, and it became apparent the main bearings were gone, because water had been getting into the oil, but in barely noticeable amounts, and the engine was cactus. With main bearings and head ruined, it was cheaper to install a low mileage, second hand engine, but I never got satisfaction over that. I should have taken the risk and sued the pants off them. However, I'm still driving that car, a 1990 Celica GT4, 4WD Turbo, and still love it, and the new engine is a beaut. Moral to story. Don't trust wannabes...and just flush out old coolant occasionally, then replace with new - don't use "special flushing solutions"..!

 

[Steve]

Most of my cruising is done in salt water, but the boat is docked up a fresh water bayou so gets a fresh water purge at the end of a cruise.
Steve W

 

[sunchaser]

As mentioned by Eric, fresh water flushing can be disastrous if not done correctly. There comes a point that engnie size and setup precludes fresh water flushing. On a Cummins, Cat or ?? with a bad turbo after cooler design, by all means correctly flush. Better yet, update your HX and after*coolers as covered under several warranty and recall instances*by Cat, Cummins etc.

But to think fresh water flushing will prolong the life of every engine and or component*is incorrect.

 

[Codger2]

paulinaM wrote:
With regards to engine flushing.................

******** That is a really cool avatar!

 

[sunchaser]

Willy

Is your genset dry stack too?