Doug R has diagnosed ur problem & given u the correct cure.
May I suggest an easy & foolproof way to get the antifreeze thru the RW system. Locate the hose from seacock to wherever it first reaches the engine or RW filter. Close seacock,if boat is in water.
Disconnect the seacock end of hose.
Stick this hose in a gal of pink RV a-freeze.
Fire up engine & run til u see pink coming out the exhaust.
Shut down-you're done.
Before launch,install a tee in this hose.
Install a ball valve on the tee & enuff hose to reach bottom of bilge
Put a strainer on the bilge
end of hose.
Next winterizing.you only have to pull the "bilge Hose" up,stick it into A/F jug,close seacock,open tee valve,& run eng. as above
Now you have the ability to use this tee bilge hose as an EMERCENCY bilge pump
. Caution:If ur bilge contains "chunks" of material,that will pass thru the strainer,it is possible to suck this crud thru RW pump & heat exchanger-hence the warning to use it only as last resort emergency
,if at all.
This works fine in my VP 2003 -takes 10min.& < 1 gal A/F. cheers/ Len