Cheech... thanks for at least keeping the thread alive :-) Yes mine is RWC. Your FWC is quite different especially as relates to thermostats. Due to your being a pressurized system and not being exposed to sea water
, it can run at a higher temp. This changes everything when it comes to the thermostat(s). You have just one but the 3qm30 RWC is a bit puzzling as regards the cooling system in that some apparently have 2 thermostats in series. To add to the strangeness I can find several 3qm30 owners on line who verify the 2 thermostats but can find no official Yanmar
source. All online manuals
from Yanmar show just the one thermostat in the housing. Strange...