"Robert Why do you measure the top of the header tank? There will be air at the top. R." Actually, Ralph, if you have a coolant recovery system with a vented filler neck atop the expansion tank, the coolant is probably completely filling the expansion tank at all times. Mine are full to brimming whenever ZI check them with the engines cooled off; so I'm sure they are full when at operating temp. Rich Gano Calypso (GB-42 Hull 295) Panama City area, Florida

Ah - good point. I concede ! R. ----- Original Message ----- From: "Rich Gano" <richgano@gmail.com> To: "Great Loop List" <great-loop@lists.trawlering.com> Sent: Sunday, July 31, 2011 4:32 PM Subject: Re: GL: Engine Room Checks > "Robert > Why do you measure the top of the header tank? There will be air at the > top. > R." > > > Actually, Ralph, if you have a coolant recovery system with a vented > filler > neck atop the expansion tank, the coolant is probably completely filling > the > expansion tank at all times. Mine are full to brimming whenever ZI check > them with the engines cooled off; so I'm sure they are full when at > operating temp. > > Rich Gano