[C320-list] Intermittent coolant leak

[Troy Dunn]

Wow, great catch Dave, I interpreted the always dry comment to mean there
was no coolant leak over there at the expansion tank.

Sara,

IF you meant there is no coolant in the tank you need to open the radiator
cap when the engine is cool and fill the heat exchanger to the top with
coolant. (Never open a radiator when the engine is hot, severe burns are
likely)    You should also fill the overflow to the "min" mark on the
expansion tank and then run your engine until warm and watch to see if
there is more coolant in this tank when the engine is warm.  The level
should rise since the coolant in your engine will expand  into the
expansion tank.    If it doesn't rise, then you probably still have air in
your freshwater system.  When the engine cools it will suck coolant out of
the overflow and back into the engine.  You should repeat this process
until the level in the expansion tank remains about the same once cool.
Of course...you'll have to find your coolant leak for this to happen.
Also, before you add coolant to your system, you'll want to make sure you
have the right coolant.    The coolant is most likely a DEXCOOL product
(generally orange, but not always).   If it is another color, you'll have
to figure out what product is in there and try to get a match.   Mixing
products can be bad if they are significantly different.  (e.g. Ethylene
Glycol products...generally green...but not always).   If you do find "the
green stuff" in there, I think most folks would tell you to do a full
system flush and replace the green stuff with the orange stuff, but you can
probably save that project until you figure out your leak.

Sorry I wasn't more helpful with the leak itself.   It looks like that post
didn't make it to the list because of the picture size.

Troy

On Mon, Jul 23, 2018 at 7:08 PM, Onat Dogruer <onatdogruer at gmail.com> wrote:

> Sara,
>
> I am not at the boat right now but if my memory serves me right, there
> is a coolant drain valve right above the fuel pump in that area you
> are describing. Could it be that it is not closing properly?
> Sounds like the leak is only happening when the engine is hot and
> coolant is pressurized(expanding) with heat. I would begin the process
> of elimination by getting to full temperature at the dock. When the
> engine is on, you will have to wait until it is at normal running
> temperature (~160F on ours) and the thermostat opens. The coolant will
> begin to heat up at the engine block and once the heated coolant
> starts circulating back to heat-exchanger, you may start to see
> 'spray'. Careful - the coolant is going to be hot at that time. Just a
> thought..
>
> Onat
> 1998, #546
>
> On Mon, Jul 23, 2018 at 2:45 PM, Sara Skinner Schroeder
> <saras951 at comcast.net> wrote:
> > Hi guys,
> >
> > Over the past 8-9 months I have an intermittent coolant leak that I just
> can't find. Over the past 8-9 months it's leaked about 5 times.  I have a
> 2000 C320 (#707) with a Yanmar 3GM30F. She has about 1450 hours on her.   I
> have narrowed it down to the following:
> >
> > 1. It is coolant - not diesel (yes I've tasted it).  It leaks about the
> equivalent of a tablespoon+.
> >
> > 2. It leaks on the starboard side of the engine compartment about
> halfway between the front of the engine compartment and the back of the
> compartment (right where the bulkhead is and right around the fuel
> pump/fuel filter). It never leaks on the port side.
> >
> > 3. It only leaks when I am on a port tack and am leaning over pretty
> hard.  Never leaks if I am not heeling over hard.  The fluid will pool on
> the starboard side of the galley floor and then drip over to the port side
> when I change tacks.
> >
> > 4. The leak seems to "spray" all over the inside of the engine
> compartment which suggests the engine needs to be under load - but when I
> turn on the engine and put her on a lean but I can't see where it's leaking.
> >
> > 5. I wipe down the inside of the compartment each time it happens so I
> can see where the new leak appears.  The pattern is always the same.
> >
> > 6. I replaced the radiator cap thinking it was leaking from the top of
> the radiator but it still leaked yesterday with the new cap on (yes, it was
> on right).
> >
> > 7. It is not coming from the overflow tank as it's always dry and there
> are no leak marks on the side of the container.
> >
> > 8. I have absorbent pads on the bottom of the engine bag but there never
> is a pink stain on the pad. The bay is dry.
> >
> > 8. I have spent hours with a little expandable mirror looking for a
> cracked hose, loose nut, anything. Nada.  Have also run my fingers over the
> entire starboard side trying to find a leak but I can only do that once the
> engine has cooled down and by then the fluid is drying up.
> >
> >
> > Am beyond frustrated so am reaching out to this wonderful community.
> Any ideas would be appreciated!  Note: I do not posses the 'guy gene' that
> makes diesel engines understandable.  Am slowing learning how to do my own
> maintenance but need pretty specific directions!
> >
> >
> > Sara
> >
> > Wandering Star/Seattle
> >
>