Topic: Raw water cooled diesel

Never mind.  In an unsurpassed explosion of self-sufficiency, I looked at the Yanmar site and saw that the engine is raw water cooled, with no reference to a fresh water cooled option.

Re: Raw water cooled diesel

The engine is designed to be raw water cooled, and as such runs quite cold in terms of operating temperatures.  The overheat switch energizes the warning circuit somewhere around 160F.  This is pretty cold, the idea being that salt will precipitate on the walls of the water jacket at elevated temperatures, which is what you dont want.  The 1GM10 in my 1974 JJT had seen 2 1/2 years of saltwater use, and when I pulled the head and inspected the water jacket I was actaully surprised as to the minimal buildup of crap.  I just used gun cleaning type wire brush to loosen up the junk that I could, and I intend to run the engine and flush the cooling system with a chemical flush before I reinstall it in the boat.  The downside to such a cold running engine is the carbon buildup on the exhaust valve, exhaust elbow, and precombustion chamber and injector.  Best I can say is regularly service the injector, and what should almost be a regular maintenance item is the removal of the exhaust elbow and having it 'dipped' to remove all the buildup.  As for the head, nothing you can do until it has to come apart for a valve job.  Well maintained, theyre a great little devil of an engine.  Reliability is directly linked to maintenance standards.....

Re: Raw water cooled diesel

The actual running temp of the engine is about 145 deg F. Prolonged running above 145F causes mineral build-up.

Re: Raw water cooled diesel

I teed in a seacock on the raw water intake hose and do freshwater flushes.  Any point in doing this?  My engine was rebuilt a few months ago, and Farymann has re-designed the cooling "jacket", which was actually useless, and now has a cast compartment...so hopefully I won't have another hole in my cylinder?!  I bought a new cylinder, which is one hp larger, so also needed new piston and new head!  quite the shock, but feel better as the engine is almost "new".
So, I have been fanatical about flushing.  Opinions?

Re: Raw water cooled diesel

the best way to flush a raw water cooled engine is a good hard drive through freshwater.  A river is handy to drive up for a quick flush.  When i wanted to flush my engine, i went for a quick trip up the fraser river.  It is very simple and effective.

Re: Raw water cooled diesel

Shannon RHIANNON Co26 318 wrote:

I teed in a seacock on the raw water intake hose and do freshwater flushes.  Any point in doing this?  My engine was rebuilt a few months ago, and Farymann has re-designed the cooling "jacket", which was actually useless, and now has a cast compartment...so hopefully I won't have another hole in my cylinder?!  I bought a new cylinder, which is one hp larger, so also needed new piston and new head!  quite the shock, but feel better as the engine is almost "new".
So, I have been fanatical about flushing.  Opinions?

How do you intend to flush the engine?  With a bucket and a length of hose?  Any chance that your engine was damaged by stray electrical currents?  Is your engine fitted with zincs? Did anyone investigate the cause of the failure?  My last diesel (1972 Westerbeke) had over 1600 hours in salt water as of 1995.  It's still alive and well.

Re: Raw water cooled diesel

Well, it was the design of the cooling jacket on the Farymanns, which they have since changed.  It was a brass sheet around the cylinder with o-rings.  An accident waiting to happen...as the sea water will eventually get past the rings...AND the cylinder had a thin spot in the wall where the stud went through to bolt the head down.  That is where the hole was both times...again Farymann has changed that.  So obviously there was a problem there.
However, you are also likely right about the electrolysis, and that makes sense, as the hole also happened to the old owner while he was in that marina for 12 years.  And, when I moved her to my marina in Vancouver I, being the paranoid one that I am, ;-) did drop a zinc over the side and monitored it for three months...and nothing.  Not a nibble by any kind of current...(I mean, it should have shown something after three months, shouldn't it have?!)
So, yes, it could be a number of things.
And yes, I use a bucket and a hose that I have a special snap on, tight, non-leaking ;-) attachment to the ball valve...and I have timed it that it takes about a minute a gallon, and I figure two minutes is enough...I mean, I basically don't want another $4,800 repair bill!  But, it's unlikely that will ever happen again....as the whole situation has changed...cylinder design as well as marina...
OK, I've rambled on enough!

“You get a boat for only one reason, because you want one.  If you’re worried about being practical, forget boats.”

Re: Raw water cooled diesel

By the way, I was also looking at the heat exchanger option.  With my Farymann, I do have room to install one.  With a Yanmar, however, you wouldn't.  And if they don't have it as an option, you would simply just tee one in yourself.
I am religious about my fresh water flushing, however, so don't anticipate any problems....but I am always prepared for disaster, ha ha!

“You get a boat for only one reason, because you want one.  If you’re worried about being practical, forget boats.”

Re: Raw water cooled diesel

My last concern on the boat I am trying to buy is the engine.  The boat has a 2002 installation of a Yanmar 1GM10, which is raw water cooled.  The boat has spent all of it's life since installation in Florida salt water. I understand the differences between raw water cooled and fresh water cooled.  Is there room for a heat exchanger in the engine compartment?  If so, can it be added without removing the engine?  Is it necessary if some care is taken to flush the engine periodically when in salt water?  If it matters, the boat is a 1984 model.