Re: Leaving the block empty
Both Merc and Volvo list adding antifreeze to reduce corrosion in their manuals as a recommended procedure, as long as you do it the RIGHT way (drain manually first, probe drains to make sure all the water is out) then there is no problem with filling the block&manifolds with AF. I have heard of people seeing a lot of rust come out on the spring start up wtih raw water cooled engines and I never see that so the AF does help. I replaced a thermo housing back in 2003 and after 6 seasons in the salt (but with AF winterizing) it has very little rust and no flaking chunks which is what iron does in salt water eventually. Like I said if you remember your chemistry Fe 02 is iron oxide, rust. Keep the 02 away and the iron won't rust as much...air and water have 02....not so with AF...
I do flush mine at winterization but honestly how much can that do after sitting with salt water in it all season....
My mechanics are not so pro closed cooling, they say if you flush at the end of the season and fill with the good AF with corrosion inhibitors your block/heads are not likely to rust through...but having said that...if you need a valve job at some point...most mechanics are not going to try to take apart a raw water cooled (salt) engine....so there is one more benefit of closed cooling. I think I will put it in my next engine because of the other mentioned advantages, more consistent temp control, way less corrosion, more efficient combustion, etc...
