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Old 10-14-2013, 03:30 PM
bigmac bigmac is offline
MC Platinum
Join Date: Jun 2005
Boat: 2004 Maristar 230 VRS
Location: Central Minnesota
Posts: 8,324
Originally Posted by Baszy View Post
Great info. thank you. I am about to winterize my 08' mcx with heater. Anybody have any different procedures for the antifreeze to the heater? My understanding is to warm engine with water,drain, run engine with antifreeze and turn on heater to draw antifreeze to the heater core. Right??
If you do that before draining all the water, the antifreeze you put in there will be diluted. It's an OK thing to do if you drain the block of your dilute antifreeze solution. The comment above about the thermostat not being open is also very true. If you're going to rely just on an engine full of antifreeze, you're probably better off pumping it in there rather than relying on the engine's natural circulation, which will be dependent on the thermostat.

If you're not certain of the procedure, I'd be inclined to recommend that you just pump antifreeze through the heater and just drain the block and manifolds as MasterCraft explains in the manual.

You could kill two birds with one stone by pumping antifreeze through your heater core from the heater supply line (splice into the 5/8 hose, or install a flushing T). In addition to filling the heater that should return antifreeze to the upper part of the engine too.

Not sure what you mean about turning on the heater. Unless you have the return valve closed, water is always circulating through the heater. "Turning it on" only turns on the fan.

I did the antifreeze through the engine thing for a couple of years, putting the raw water intake line into a five gallon bucket while running the engine. It was the hassle of doing that, as well as the rest of the stuff, that made me decide that paying the dealer to do it just worked a lot better for me. He "pickles" the boat too, in -100 propylene glycol throughout the engine and heater. I don't know his technique exactly, but it's worked well for me. Never had any issues the the last 5 or 6 years, and as a bonus, I rarely need to change the RW impeller. Come the spring, there are no hoses to reconnect...just drop the boat the water and start her up. Dealer's been doing this to literally a thousand boats a year for well over a decade and proven it to be an effective technique.
'04 MariStar 230VRS/MCX

Last edited by bigmac; 10-14-2013 at 03:42 PM.
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