*pressure* water into the raw water intake can indeed overfill the waterlift
muffler once the engine is not running, and it doesn't take long.

As far as "cleaning out" the cooling system by flushing after use, that just
doesn't play. The cooling system gets clogged up by a.) "carbonates" loosely
meaning the various salts that plate out on the cooling system walls as hot
salt water (which has LOTs minerals in it), and b.) crud -- like silt -- that
falls out of the water as it flows through the cooling system.

And Yanmar raw water cooled engines were more suseptable to both a.) and b.)
than other raw water cooled engines of the era.

And again, do NOT turn pressure water on when the engine is not running.
Better is to run the water into a 5-gallon bucket and suck it from the bucket
into the engine.

your explanation was not clear that the engine MUST be running.

On 27 Jan 2004 15:22:20 GMT, (JAXAshby) wrote:

larry, do that as you suggest on a Yanmar with a waterlift muffler and you
will
cause some expensive to repair damage.

How? The engine is RUNNING during the flush. Feeding fresh water
into the stream into the RUNNING water pump simply replaces salt with
fresh. Any fresh water not pumped into the engine by the engine's OWN
water pump (whos impeller, by the way, meters how much water it passes
because my way has no hose pressure on it to speak of)...any excess
fresh water is simply fed backwards through the seawater strainer,
probably clearing it of the crap and run overboard unless the intake
or strainer is clogged, of course.

As the engine is RUNNING, there is no waterbox flooding or exhaust
backup because of the exhaust pressure of the engine. No excessive
water pressure is applied to the engine, any more than the water the
seawater pump on the engine imparts on it.

How's it going to destroy the engine this way. Simply turn off the
hose as soon as you stop the engine......before the seawater is pumped
through it, again.

You'd probably NEVER have to flush or core the cooling system if you
did it every time you used it.....even on closed systems with a heat
exchanger!


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

On 27 Jan 2004 15:22:20 GMT, (JAXAshby) wrote:

larry, do that as you suggest on a Yanmar with a waterlift muffler and you will
cause some expensive to repair damage.

How? The engine is RUNNING during the flush. Feeding fresh water
into the stream into the RUNNING water pump simply replaces salt with
fresh. Any fresh water not pumped into the engine by the engine's OWN
water pump (whos impeller, by the way, meters how much water it passes
because my way has no hose pressure on it to speak of)...any excess
fresh water is simply fed backwards through the seawater strainer,
probably clearing it of the crap and run overboard unless the intake
or strainer is clogged, of course.

As the engine is RUNNING, there is no waterbox flooding or exhaust
backup because of the exhaust pressure of the engine. No excessive
water pressure is applied to the engine, any more than the water the
seawater pump on the engine imparts on it.

How's it going to destroy the engine this way. Simply turn off the
hose as soon as you stop the engine......before the seawater is pumped
through it, again.

You'd probably NEVER have to flush or core the cooling system if you
did it every time you used it.....even on closed systems with a heat
exchanger!


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

larry, do that as you suggest on a Yanmar with a waterlift muffler and you will
cause some expensive to repair damage.

On Mon, 26 Jan 2004 23:17:52 -0500, "Leanne" wrote:


When we were running the Volvo that was raw water cooled, there
was an attachment, in the water line inboard of the strainer that
allowed for flushing. About a quarter turn on the fresh water
hose was sufficient for enough cooling. It also worked when you
went to the hard for the winter as it was an easy way to get
antifreeze into the cooling system.

Leanne


If one were to introduce fresh water from the hose to a T after the
salt water strainer (with a valve in the fresh water inlet, of course,
to shut off when not flushing), many good things would happen at once.

You'd be providing fresh water in the intake of the engine water
pump.....flushing the engine.

You'd be BACKFLUSHING the intake system and strainer, probably blowing
out the crap in the strainer back overboard.

The backflushing of the intake with fresh water would eliminate any
"pressure" from the hose as the system would be wide open to the sea.
There wouldn't be any pressure to worry about.

In all honesty, this isn't my idea. My Mercury Sport Jet 175 in my
Sea Ray Sea Rayder F16XR2 is fresh water flushed this way. The only
difference is it has no water pump to buy impellers for. 35 PSI of
seawater pressurizes the water jacket from the BIG pump under the
stern. It simply has a pipe pointing into the 60 gallons per second
pressurized water stream just aft of the stator inside the nozzle's
pressure chamber.

There's no reason not to put a T with a ball valve to the fresh water
hose tap in the hose between the strainer and the water pump. I,
personally, like the idea of flushing out the salt in ANY cooling
system after use. Most yachtsmen, who are too lazy to eliminate the
water ingestion into their diesel tanks by filling them after use,
wouldn't flush the engine, either. To many, engines are just
disposables, anyway. The water jacket, all its fittings and the main
jet pump on "Tess Tickles Too", after 6 years of salt water use, look
just like the first day I launched it.....just because it's flushed
after each use before being stored. It's stupid to leave salt
corroding away the inside of an expensive diesel engine, eating away
at the zinc pencils, when you're not using it.....


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

On Mon, 26 Jan 2004 23:17:52 -0500, "Leanne" wrote:


When we were running the Volvo that was raw water cooled, there
was an attachment, in the water line inboard of the strainer that
allowed for flushing. About a quarter turn on the fresh water
hose was sufficient for enough cooling. It also worked when you
went to the hard for the winter as it was an easy way to get
antifreeze into the cooling system.

Leanne


If one were to introduce fresh water from the hose to a T after the
salt water strainer (with a valve in the fresh water inlet, of course,
to shut off when not flushing), many good things would happen at once.

You'd be providing fresh water in the intake of the engine water
pump.....flushing the engine.

You'd be BACKFLUSHING the intake system and strainer, probably blowing
out the crap in the strainer back overboard.

The backflushing of the intake with fresh water would eliminate any
"pressure" from the hose as the system would be wide open to the sea.
There wouldn't be any pressure to worry about.

In all honesty, this isn't my idea. My Mercury Sport Jet 175 in my
Sea Ray Sea Rayder F16XR2 is fresh water flushed this way. The only
difference is it has no water pump to buy impellers for. 35 PSI of
seawater pressurizes the water jacket from the BIG pump under the
stern. It simply has a pipe pointing into the 60 gallons per second
pressurized water stream just aft of the stator inside the nozzle's
pressure chamber.

There's no reason not to put a T with a ball valve to the fresh water
hose tap in the hose between the strainer and the water pump. I,
personally, like the idea of flushing out the salt in ANY cooling
system after use. Most yachtsmen, who are too lazy to eliminate the
water ingestion into their diesel tanks by filling them after use,
wouldn't flush the engine, either. To many, engines are just
disposables, anyway. The water jacket, all its fittings and the main
jet pump on "Tess Tickles Too", after 6 years of salt water use, look
just like the first day I launched it.....just because it's flushed
after each use before being stored. It's stupid to leave salt
corroding away the inside of an expensive diesel engine, eating away
at the zinc pencils, when you're not using it.....


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

"Jeffrey P. Vasquez"
wrote in message
...
Hi all,

I am advised to flush a raw-water cooling system on a Yanmar
2GM with fresh
water. I have a couple of questions on execution to any kind
soul that can
offer some advice.

I'm thinking of running a dock hose down and hooking it up to
the hose
coming off the through-hull intake, turning the faucet on,
starting the
engine and just letting it go. However, I'm concerned about
overpressuring
the system and filling the water lift to the point it dumps
into the
engine. Is this a valid concern? Is there a better way to
accomplish this?
There's always positive pressure on the system from the
through-hull
anyway, so I'm assuming as long as I'm pressurizing it from
upstream of the
water pump, I'm safe. True?

When we were running the Volvo that was raw water cooled, there
was an attachment, in the water line inboard of the strainer that
allowed for flushing. About a quarter turn on the fresh water
hose was sufficient for enough cooling. It also worked when you
went to the hard for the winter as it was an easy way to get
antifreeze into the cooling system.

Leanne