fresh water flushing system for Yanmar 300hp diesel

I am looking for suggestions for installing a fresh water flushing system for my Yanmar diesel. Any thoughts ?

I have seen a T just after the sea strainer used, it can be used for flushing with fresh or salt away (which is what this owner did) make sure you have enough pressure to keep up with the pump. An idea and not a bad one, instead of hooking up your hose put the flush side in a five gallon bucket so you can observe and make sure the supply side is keeping up with demand. In addition you can use the t side as an emergency bilge pump.

Simlar to groco sea strainer t - Google Search

This is what I did for a fresh water flush. I installed a Tee in the hose between the sea strainer and the engine water pump. When I'm done with a cruise I hook up a water hose to the Tee. I keep the valve off while hooking up the water hose and turn the water on to about half pressure. The engine is still running. I open up the valve and then close the seacock. I now have fresh water going into the engine. I let it run about 5 minutes and then turn the engine off and disconnect.

I've seen a number of good posts within boatdiesel.com on this, I think the key with all these idea's is design it so it's easy to use, if you are going through all kinds of girations for it to work there is a good likelyhood you won't be doing it as much.

My method is very simple.

I disconnect my hose that is attached to my sea water intake valve, Kingston valve or whatever. Get a 5 gal bucket (clean) and put in low and close enough to the hose so it will easily reach the bottom of the bucket. Get one or more buckets w fresh water in them to replenish the water pumped out while the engine is running. Start the engine and pour water into the suction bucket until the water is gone. Repeat if necessary. Not necessary for me as I have a small engine. Open and close the sea water inlet valve as necessary.

If you unhook the sea water inlet hose now and then (or often) it should be easy to remove. Good place to double clamp.

??

windmist said:

This is what I did for a fresh water flush. I installed a Tee in the hose between the sea strainer and the engine water pump. When I'm done with a cruise I hook up a water hose to the Tee. I keep the valve off while hooking up the water hose and turn the water on to about half pressure. The engine is still running. I open up the valve and then close the seacock. I now have fresh water going into the engine. I let it run about 5 minutes and then turn the engine off and disconnect.

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Who's T did you use? and what other items such as the fitting above the T? I too am getting ready to install similar set up and thought this was slick. I have three motors to flush and would like to make sure it's easy - something like a quick disconnect so I can transfer from each engine to flush would be slick.

Yes I would say simple as well, but certainly not easy like flipping a valve handle and turning on a hose, but everyone has their own methods of skinning a cat.

manyboats said:

My method is very simple.

I disconnect my hose that is attached to my sea water intake valve, Kingston valve or whatever. Get a 5 gal bucket (clean) and put in low and close enough to the hose so it will easily reach the bottom of the bucket. Get one or more buckets w fresh water in them to replenish the water pumped out while the engine is running. Start the engine and pour water into the suction bucket until the water is gone. Repeat if necessary. Not necessary for me as I have a small engine. Open and close the sea water inlet valve as necessary.

If you unhook the sea water inlet hose now and then (or often) it should be easy to remove. Good place to double clamp.

Click to expand...

bshillam said:

Who's T did you use? and what other items such as the fitting above the T? I too am getting ready to install similar set up and thought this was slick. I have three motors to flush and would like to make sure it's easy - something like a quick disconnect so I can transfer from each engine to flush would be slick.

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I got all my parts from Fisheries Supply. Do you have their catalog? They do have an on-line catalog as well. I also made up a short connecting hose that goes between the Tee and the water hose. It has female fittings on each end and a shut off valve.

A friend of mine has a flush system that connects his engine and generator together for flushing. As I recall, he just switches a valve to flush one engine or the other. Three engines could get complicated.

in many cases the easiest thing is to just remove the top of the sea strainer and let the fresh water hose fill it up ...start the engine with just enough flow going in to remain constant with what the engine is sucking out.

I will have a valve installed in the lid of my water strainer, the pressurised fresh water hose is permanently attached to this valve: Make sure the water pump for the fresh water system is turned on. While the engine is running at idle, open the fresh water valve, close the strainer sea cock, run the engine for a few minutes, then shut down the engine and close the fresh water valve.
The lid on the strainer is transparent so it is possible to see if the strainer is full of water or not...

Searios said:

I will have a valve installed in the lid of my water strainer, the pressurised fresh water hose is permanently attached to this valve: Make sure the water pump for the fresh water system is turned on. While the engine is running at idle, open the fresh water valve, close the strainer sea cock, run the engine for a few minutes, then shut down the engine and close the fresh water valve. The lid on the strainer is transparent so it is possible to see if the strainer is full of water or not...

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When you do this there are two things you need to always do otherwise you risk creating bigger problems than you are trying to solve. 1) Shut off the fw feed supply BEFORE you shut down the engine. 2 Always re-open the saltwater through hull.

Obviously your engine shutdown switches and valves need to be within arms length for the shutdown phase. Stopping the engine first will collapse the fw feed hose preventing the overfilling of the exhaust system thus preventing the potential hydro locking of the engine. Re-opening the sw through hull may seem obvious but stuff does seem to happen and people sometimes forget.

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There are many methods and reasons to freashwater flush (or not) your engine(s)...as long as you know your system and have taken the proper safeguards...unless you are doing exactly like someone else...their method or checklist may not really apply to your method.

Pretty much if you don't hydrolock your engine or forget to open the seacock...whatever method or complicated system you want to employ will be fine.

I have 315 Yanmar's and at idle the water fill rate in a bucket to the suction rate on the engine are equal. As stated on boatdiesel/Tony Athen's, just leave the through hull open, any excess will be go out the bottom and no worries of timing valves etc.

I had a machine shop drill holes in the top of the strainer caps and install a ball valve. I connected about 4 ft of sanitation hose with a female garden hose connector on the end to the ball valve. I had to use sanitation hose because the engine would suck so much water it would collapse a regular garden hose.

When I flush my Cummins 330 6BT's I connect the fresh water to the white sanitation hose and turn on the fresh water, I start the engines, open the valve on top of the strainer, close the raw water intake valve (sea cock) , and run the engine for about 10-15 minutes at idle only.

When done if the admirals around she shuts down the engine and I simultaneously shut off the water at the ball valve on top of the strainer. If she's not around, I shut down the engine at the helm and quick like a bunny run down to the ER and shut off the ball valve, maybe 10 seconds.

I leave the sea cock closed. Opening it is on my engine start checklist.

Been doing this way for 3 years, hope it's right.

Does anyone believe the exhaust elbow will last longer with a 5 min flush?

The heat exchanger for engine and tranny with FW cooling could care less , if its a quality item.

So the question is why bother?

FF said:

Does anyone believe the exhaust elbow will last longer with a 5 min flush?

The heat exchanger for engine and tranny with FW cooling could care less , if its a quality item.

So the question is why bother?

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Ditto...inferred ealier..thanks for the supportive thinking...

But it makes me feel good!

timjet said:

But it makes me feel good!

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Nothing better than that until your wife finds out....

psneeld said:

Nothing better than that until your wife finds out....

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Hopefully she won't cut the wrong hose!

This post may be of use.

FWIW: Before embarking on this little project, I did a fair amount of internet reading on freshwater flushing of engines - Yanmars in particular. A significant number of the articles concluded that it is very well worth while doing so. Heat exchangers stay cleaner, corrosion markedly reduced and water injection elbows last longer. Turbos are probably happier not sleeping in a salt-laden atmosphere - at least I hope so.

Shoalwaters said:

Heat exchangers stay cleaner, corrosion markedly reduced and water injection elbows last longer. Turbos are probably happier not sleeping in a salt-laden atmosphere - at least I hope so.

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Makes sense to me. Most folks flush their outboards at the end of the season or sooner, why not the diesel inboards.

If you are going to do it..there are productls like "salt away" to really enhance the process...if you have ever seen salt that has heat dried on metal...just flushing alone doesn't seem to get it all....
Salt-Away Engine Flushing ...

the system was an option on some of the early 2000's Sea Rays that I've run.

I do agree with psneeld, way back in a previous life I had a 1976 V6 Merc 175 (black max), they were noted for rotting out the exhaust baffle and taking out the motor, I had a brand new power head so I faithfully flushed after every use, after 5 years figured I'd take the baffle off and take a look, I couldn't believe all the salt/mineral build up along with a corroded plate, it looked like I never flushed it.

I do believe that fresh water flushing helps and so do the gurus on boatdiesel, specifically Tony Athens.

Without a doubt they will reduce zinc wastage and for no other reason that makes it worthwhile for me. Zincs cost about $10-20 per year to replace on my boat. I suspect that number will drop to a fourth of that with fresh water flushing.

Scale and marine growth will be less. A seawater kept boat will lose all of the barnacles on the bottom.(well they probably won't be gone, they will just be dead) after a few weeks in fresh water. The same thing happens to marine growth inside heat exchangers if they are left in fresh water in between sea water runs.

And even though the metals on modern heat exchangers will resist corrosion and zincs protect them even further, I like the extra benefit of freshwater sitting for 95% of the time.

It cost about $20 in parts to add a nipple, elbow and ball valve to the cover on my strainer. It takes about 5 minutes to flush after each use. Well worth it IMO.

David

Of course flushing helps with zincs...regular zincs are not recommended for freshwater...either aluminum or magnesium alloys are...so if flushing is preserving zincs, are they really doing their job?

The zincs protect the bronze castings and cupronickel tubes of the heat exchangers when they are exposed to seawater. When they are in fresh water, which should be 95% of the time in most cases if you flush with fresh water, then there will be very little corrosion of the bronze and cupronickel and little wastage of the zinc.

The fact that the zincs don't do much good in fresh water is exactly why you want to flush with fresh water. Keep the bronze/cupro-nickle in fresh water and there won't be any significant corrosion.

David

djmarchand said:

The zincs protect the bronze castings and cupronickel tubes of the heat exchangers when they are exposed to seawater. When they are in fresh water, which should be 95% of the time in most cases if you flush with fresh water, then there will be very little corrosion of the bronze and cupronickel and little wastage of the zinc.

The fact that the zincs don't do much good in fresh water is exactly why you want to flush with fresh water. Keep the bronze/cupro-nickle in fresh water and there won't be any significant corrosion.

David

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Bronze and cupro-nickle also do fine in saltwater...bronze through hulls last 50+ years in many cases.... thus why many people don't bother with fresh water flushing.

Don't get me wrong ....I'm still debating...but there's strong arguments on both sides and I just like to know the reasons that really matter.

.I'm still debating...but there's strong arguments on both sides and I just like to know the reasons that really matter.

The belief that doing something ,anything is better than doing nothing.

Of course the boat is plugged into shore power 99% of the time , so with fresh water in the sea water system perhaps the zinc electrodes should be swopped for magnesium, the usual FW protection.