MarineEngine.com does not offer troubleshooting assistance or repair advice by email or by telephone.
You are invited to join our public Boat Repair Forum to seek assistance from other members.
You may also visit the Boat Motor Manuals section of our site to obtain a service manual.
I don't think there is supose to be antifreeze in the heat exchanger.
There are two wet sides to the heat exchanger.
.... the ethylene glycol side, whereby the coolant surrounds the tube bundle.
.... the seawater side, whereby the seawater passes through the tube bundle.
The pencil anode installs in the seawater side of the shell and tube system.
Isn't only fresh water coming out of the zinc plug hole
That would be either river, lake or ocean water.
By the way, the pencil anode serves two purposes.
.... anode protection on the seawater side.
.... drain plug for draining the seawater.