It's the exhaust manifold passage between the small inlet port on the
head closest to the flywheel and the manifold water inlet. As you
probably know, the cooling water enters the manifold on the bottom of
the manifold between the aft and middle heads. There are three small
holes where the cooling water leaves the manifold and enters the head.
There are three large rectangular holes where the cooling water
re-enters the heads, then leaves via the thermostat. (At least that's
how I think it works. The aft and middle ones are very clear (dedspite
being physically smaller).

I had the thought to put a pressure gauge somewhere on the cooling
circuit to monitor the cooling water pressures/impeller status.

-Ryan
S/V Whale II

"dbraun" wrote in message alkaboutboats.com...
Which passage is it? One of those passages is supposed to be blocked.


David
S/V Nausicaa