MD6a raw water cooling in fresh water

wemccourt · Jan 6, 2009

John,

There is a non-toxic antifreeze available for use in winterizing RV potable water systems over here. It may be available to you thru camping or outlets with supplies for trailers or caravans as you call them in the UK

Bill McCourt
Reston, VA

j.hunter9999 · Jan 6, 2009

John,
I assume you plan on running the engine during the winter? I have RV
antifreeze in my head and pipes. Its perfectly safe for discharge
into the lake. I also drained the water from the engine (she is on
the hard for the winter).

I'd love to see if anyone else has run a closed loop raw water system.
I did some engine work and am interested to find out if the engine is
going to run.

Jack

perry_basden · Jan 7, 2009

Hi, John... et al

I've been following this thread with some interest. I'm not sure what you
are asking ... "Has anyone tried re-circulating the exhaust water as a poor
man's "enclosed" system for winter running?" One must be very careful when
using exhaust water for re-circulating purposes.

Under normal engine operation the water is fed into the engine by the raw
water pump. The water passes through the engine block and is then piped
separately into the exhaust elbow aft of the engine exhaust. This water,
which has already absorbed the heat of the engine block, is then used to
cool the exhaust system from that point onward until it is expelled from the
exhaust transom fitting along with the combustion exhaust gasses.

If you try re-circulating this water you must be very careful that it does
not build up in the exhaust system where it may flow backward through the
valves and into the combustion cylinders. Water in the cylinders can cause
some major grief if you try and start the engine. This same problem has
come up when repeatedly trying to start a stubborn engine. The water cannot
be blown out of the exhaust and will flood the cylinders if one is not
careful.

If you were to install a heat exchanger that would allow you to run
anti-freeze in the engine and thus avoid the freezing problem, you would
also have to be sure to drain the heat exchanger after every use or flush it
with anti-freeze to prevent freezing. The same can be done directly with
the engine. So in reality, I don't think you would have gained much by the
heat exchanger installation.

If you are ecologically minded, you could always hang a bucket on the
transom to catch the anti-freeze/exhaust discharge when the engine is first
started and then dispose of the material in a more acceptable manner.

Best regards

Perry Basden
Windsor, Ontario, Canada

MD6a raw water cooling in fresh water

Vega1447

.

wemccourt

.

j.hunter9999

.

Vega1447

.

perry_basden

.

Vega1447

.