Our
engine started making a strange
noise right at the start of our
cruise south. To me it sounds like steam, it doesn't sound like a
noise that relates to
RPM mechanically... kind of like a pressure cooker sh-sh-sh but without any regular rhythm in both frequency or volume (ie, it's a random shssshhhshhhhSHHHshhhshhhhshhhhhshhhh. Otherwise the
engine does not operate outside of normal, no steam in the
exhaust that I can see (it is under the stern, so it would have to be significant to be visible, but I look out the stern lights and don't see anything), no difference in performance or temperature, but she consume
coolant. 2-3 hours of running and the reserve (the plastic bottle that has the FULL WHEN COLD/FULL WHEN HOT marks on it) empties out.
It hasn't really gotten worse for 50 hours of running or so. I flushed the
coolant (it was muddy, had to fill and flush 4-5 times to get it to be clear again), and I've changed the
oil.
Any ideas on what I should check?
Engine is a Cummins 4BT Turbo
Diesel. I tried poking around it with a mechanics stethoscope yesterday but couldn't figure out where it's coming from.