330 excalibur losing coolant

[xtremeBS]

Hi,

Just got the boat out for the first time this year, all seemed in good order but the coolant was low. Topped up and started (its closed cooling).
Its losing about 1/2 pint in 5 mins with no sign of any external leaks. Checked the oil and doesn't appear to be any coolant getting in the oil. Only thing we could think of is the heat exchanger with an internal leak and its going out through the manifolds.
We intend getting some uv dye in there next weekend to see if we can trace it, but any ideas would be appreciated.

[Neverenough]

Are you seeing any oil on the water surface when boat is running? Come to think of it I'm not sure coolant will leave that on top of the water. Radiator shop could check the heat exchanger for you.