" Lou,
If you're not seei
" Lou,
If you're not seeing any leaks, and not smelling anything in the bilge, then the coolant is going out the exhaust. This can only happen one of two ways. A blown head gasket or a leak from the freshwater directly to the raw water. Fortunately the second is the more likely and the cheaper to repair.
To check for a blown head gasket. First pull the dip stick and look at the oil, there should not be any light brown foam. If so you have coolant getting into the oil most likely from a leaky head gasket. Next fill the coolant and start the engine with the radiator cap OFF. Look for any oil floating by or bubbles in the coolant. If you see bubbles or coolant gets ejected from the expansion tank it's time to pull the heads. A more through diagnosis is to do a compression test.
From the diagram above a leak to the raw water can only mean an internal leak in the heat exchanger. Drain the coolant, take off the heat exchanger, and have it cleaned and pressure tested at a radiator shop. If you haven't done so recently, check the exhaust manifolds and elbows at the same time. They can be pressure tested also if your unsure of their status. A leak in a exhaust manifold or elbow can easily blow your engine.
Good luck
Chuck "
