[C320-list] Intermittent coolant leak

[Onat Dogruer]

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
>