CAPACITY: Engine Closed Cooling System

[wolfe10]

2003 Catalina 350 with standard Westerbeke Universal M35BC.

Getting ready to change coolant. Anyone recall total coolant capacity (yes, including loop to/through water heater)?

It may be in the manual, but not at the boat right now and want to buy the coolant before starting the project.

Thanks.

Brett

[jonnjones]

4 liters

[wolfe10]

Thanks, Jonn.

Sure seems small for engine, heat exchanger, lines to water heater and heater itself.

[MarkElliott]

To the best of my recall I used one gallon of the Napa diesel truck antifreeze cut 50/50. I have 2 gallons of stuff labeled “waste antifreeze from Boat” in the garage at home. Do your self a favor and replace the line from the overflow to the coolest resivour while in there.

[wolfe10]

Yup, doing complete cooling system "tune-up": all new hoses, boil out heat exchanger and new gaskets, etc.

[wolfe10]

Just to close the loop on this. One gallon of coolant concentrate is plenty. Change takes a little over 1 gallon of coolant/distilled water. Bleeding air at thermostat housing and particularly at water heater (both have petcocks) is a real pain, but absolutely necessary to remove air from the system.

As most are already aware, the standard heat exchanger ZN is about 3/8" too long and if not shortened, "two blocks" into the center web of the heat exchanger and BREAKS OFF. Easy to shorten with a hack saw. Broken ZN's sit in the bottom of the heat exchanger and can block water flow through some of those lower tubes.

If you suspect pieces of broken ZN, the fix is pretty easy and can be done with the heat exchanger in place. The ZN is on the starboard end of the heat exchanger.

Buy:
New ZN and shorten.
Buy new heat exchanger end gasket and O ring (need both).

Close through hull.

Place something to catch the raw water under the ZN and remove it. Let raw water in heat exchanger pretty much drain. Remove end cap. With your fingers, pull out any remaining pieces of ZN. Clean heat exchanger mating surface and end cap-- I use 400 wet dry. Reinstall end cap with new gasket and Oring. Open though hull.