During adverse conditions, 45knt gusts, blinding rain a tide going out and a
current besides, (At one point I looked at the GPS and with the engine
running 2400rpm we were going 0 knts) shortly after this the engine
overheated so I shut it off, there was enough sail sticking up so I had
steerage but I did get blown off course. After about half-hour of being
blown around I started the engine, the temperature came down to normal
slowly and the engine ran fine for the next few hours it took to get back to
the slip. Is this engine getting too old (1979) ? Thermostat and impeller
about 20hrs., raw water cooling, strainer not clogged, no air leak.
Do the water passages get clogged after years of use and if the engine is
under strain it will show up as overheating?

On Sat, 09 Aug 2003 08:11:22 -0400, "Mr. Catfish"
wrote:

Do the water passages get clogged after years of use and if the engine is
under strain it will show up as overheating?

Sure. The heat exchangers need occasional boiling out at a radiator
shop.

Lemme ask another question. We had a 3GM on an Endeavour 35 sloop
that overheated. When I opened the cap on the heat exchanger it was
NEARLY EMPTY even though the level in the recovery tank was full!
What had happened is the hose to the recovery tank goes from the heat
exchanger to the CAP on the recovery tank, then depends on a tube that
goes from the cap down to the bottom of the tank to suck fluid back up
as the engine cools. It sucks! The hose inside the tank fell off
because the idiots who made it have it trying to grab onto a slippery
piece of plastic that's NOT a barb. I gave up trying to keep it on
the cap's little pipe and replaced the whole tank with a recovery tank
from an auto parts store where the hose came out the BOTTOM in the
first place, making opening the cap easier without all the hose crap
in the way.

Every time the engine ran, antifreeze pressurized the cap on the heat
exchanger which allowed fluid to flow to the tank. Every time the
engine cooled, the fluid in the heat exchanger contracted, SUCKING AIR
FROM THE TANK WITH THE DAMNED HOSE LAYING INSIDE IT.

Stupid design, stupid installation......almost burned up the engine!

Idiots!



Larry

Extremely intelligent life must exist in the universe.
You can tell because they never tried to contact us.

Do the water passages get clogged after years of use and if the
engine is under strain it will show up as overheating?
ANSWER: A MOST DEFINITE --- YES!

Your engine is probably 'salted': both in the exhaust manifold and the
internals of the engine proper. Especially if the thermostat opens at
above 190 degrees the salting process is amplified.
Sea water when heated above 150 degrees will precipitate carbonates
(salts) which CONTINUOUSLY form an insoluble coating on the engine
internals. This fouling will retard heat transfer and if the 'salt'
deposition is significant will block the flow of cooling water.

Best remedy is to drain the cooling water, then add MARSOLVE
(www.marsolve.com) circulate* this through and let sit to dissolve the
'salt' accumulations. Marsolve is commercial descaling compound that is
biodegradable and will NOT dissolve the base metal of the engine. Many
use muriatic acid to 'pickle' marine engine internals but the muriatic
will also react with or dissolve engine base metal. ALL salt water
cooled engines should be so 'pickled' every few years to remove the fouling.

Once the engine is 'pickled' make a decision:
1. Install a thermostat that opens fully at 135 degrees and suffer less
thermodynamic efficiency because the combustion chambers operate at a
less combustion-efficient state. OR
2. Plan to 'pickle' the engine every few years.

*circulate = pull the inlet water hose from the closed through-hull.
Remove the hose from the water injection port to the heat/steam rise
elbow. Put the inlet water hose, put a temporary hose from the muffler
water injection into a large bucket, pour the marsolve into the bucket
and run the engine until the marsolve fills the engine, Keep running
until the marsolve solution is warm, then shut down the engine and let
the marsolve soak. Etc.

On Mon, 11 Aug 2003 04:07:03 GMT, RichH wrote:


Once the engine is 'pickled' make a decision:
1. Install a thermostat that opens fully at 135 degrees and suffer less
thermodynamic efficiency because the combustion chambers operate at a
less combustion-efficient state. OR
2. Plan to 'pickle' the engine every few years.


I've always felt bad bringing a nice yacht to a dock then just leaving
it all corroding away for sometimes weeks at a time leaving salt in
the heat exchanger and exhaust. I don't do that to outboards and
jetboats. Why is it "ok" in nice boats?

Is there a particular reason expensive yachts don't have fresh water
flush systems on, say, a sailboat auxiliary? It's so simple to
install to simply backflush it into the sea and close the seacock,
leaving the system full of clean, salt-free, fresh water that will
absorb the salt.

These engines aren't immune.....


Larry

Extremely intelligent life must exist in the universe.
You can tell because they never tried to contact us.

Thanks, I will pickle the engine, I got a copy of Good old boat yesterday
and they have an article on cleaning out raw-water cooled engines using
muriatic acid. Same technique would work with marsolve.

George Pappas
S2 9.2A "EXO"

In these engines with water lift mufflers extra pressure is required
of the raw water pump at high power to over come the exhaust pressure.
Motoring into rough water adds air bubbles to the system reducing
pressure and can stop all flow of water. A through hull water scoop
helps control this problem by forcing the air through the pump.
Have you cleaned out the outlet fitting on the heat exchanger and the
inlet water fitting on the exhaust elbow? Has the raw water pump cam
been replaced? In charter boats these cams only last about three years
in the older small Yanmar engine.
From the author Of books on Boat Refrigeration
http://www.Kollmann-marine.com


"Mr. Catfish" wrote in message ...
During adverse conditions, 45knt gusts, blinding rain a tide going out and a
current besides, (At one point I looked at the GPS and with the engine
running 2400rpm we were going 0 knts) shortly after this the engine
overheated so I shut it off, there was enough sail sticking up so I had
steerage but I did get blown off course. After about half-hour of being
blown around I started the engine, the temperature came down to normal
slowly and the engine ran fine for the next few hours it took to get back to
the slip. Is this engine getting too old (1979) ? Thermostat and impeller
about 20hrs., raw water cooling, strainer not clogged, no air leak.
Do the water passages get clogged after years of use and if the engine is
under strain it will show up as overheating?

From: (Richard Kollmann)
Organization: http://groups.google.com/
Newsgroups: rec.boats.cruising
Date: 11 Aug 2003 05:59:20 -0700
Subject: Engine overheat-yanmar 2qm15

In these engines with water lift mufflers extra pressure is required
of the raw water pump at high power to over come the exhaust pressure.
Motoring into rough water adds air bubbles to the system reducing
pressure and can stop all flow of water. A through hull water scoop
helps control this problem by forcing the air through the pump.
Have you cleaned out the outlet fitting on the heat exchanger and the
inlet water fitting on the exhaust elbow? Has the raw water pump cam
been replaced? In charter boats these cams only last about three years
in the older small Yanmar engine.
From the author Of books on Boat Refrigeration
http://www.Kollmann-marine.com


Well, damn, that is another angle I have not heard before, my old yanmar is
raw water cooled, just a thermostat to direct the water for temp. control,
I'll check the inlet fitting when I flush the engine, and replace the raw
water pump cam. Thanks. Maybe I should get a storm sail?!!

George Pappas
S2 9.2A "EXO"

Not the same ------

You flush an outboard to prevent corrosion from occurring.

You cant flush the already solid precipitated carbonates as once they
form they are insoluble in water. What you formed by the elevated
temperature (greater than 105 degrees) is ROCKS!

I sued to 'pickle' all the time with muriatic (hydrochloric) acid ...
you can remove a fair amount of engine base metal if youre not careful.
Muriatic pickling does remain a valid process - just be very careful.

Mr. Catfish wrote:

Thanks, I will pickle the engine, I got a copy of Good old boat yesterday
and they have an article on cleaning out raw-water cooled engines using
muriatic acid. Same technique would work with marsolve.

George Pappas
S2 9.2A "EXO"

Mr. Catfish wrote:

During adverse conditions, 45knt gusts, blinding rain a tide going out and a
current besides, (At one point I looked at the GPS and with the engine
running 2400rpm we were going 0 knts) shortly after this the engine
overheated so I shut it off, there was enough sail sticking up so I had
steerage but I did get blown off course. After about half-hour of being
blown around I started the engine, the temperature came down to normal
slowly and the engine ran fine for the next few hours it took to get back to
the slip. Is this engine getting too old (1979) ? Thermostat and impeller
about 20hrs., raw water cooling, strainer not clogged, no air leak.
Do the water passages get clogged after years of use and if the engine is
under strain it will show up as overheating?


The other comments are useful, particularly cleaning out the raw water
cooling passages, but 2400 RPM seems VERY low revs for what I expect
would be high-cruise (or higher) engine settings. As I recall, the older
Yanmars had a 3200-3600 max range like the newer ones such as ours
(2GM20F). In other words, this sounds like an over-propped engine which
would overheat at relatively low power settings.

We propped for our 1-hour max setting. True to specs, the engine
overheated about an hour after we firewalled it. (that hour got us
nearly a quarter nm further, though we had to drop revs drastically for
a few minutes to let the cooling system catch up.) When running at the
continuous setting (200 RPM lower), we cruise for as long as we want --
at very high consumption rates.

We now cruise at 2200-2400 normally, which gives us about 80% of hull
speed in flatish water. If we're rushed, like a couple of weeks ago, I
can bring the boat's speed up high enough to maintain surfing conditions
much of the time in downwind conditions and can punch through waves when
we're going upwind at nearly hull speed (though at an angle, not head-on
with our blunt bow section).

If we pitched a bit more aggressively, we could cruise faster at lower
RPMs, but couldn't go as fast when we really needed it.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/