Winterizing 5.0 liter Volvo-Penta engines with raw

This has been discussed many many times on many forums and it is risky at best. The thermostat does cycle open and closed but not all the way open and not all the way closed. One way to see it for yourself is take a pot, hand a stat from a coat hanger wire and heat it up. You will see how it operates then. Most modern stats start to open at 160 (remember that fact) and are fully open at 180. Now if your engine idles at 160 on the gauge and not higher, when you are running it on the water hose, what does that tell you?? That it is starting to open, not all the way open, and that's what you would need to have happen if you want to use this method without draining the block first. If its just starting to open there is not enough flow for the water in the block to exit. And the antifreeze does NOT get warmed by the block until it's sucked in by the circ pump. What happens is, when the stat is closed, the raw water comes in and gets diverted out the manifolds. When the stat opens, hot water comes out the stat, and exits via the exhaust, the antifreeze comes in the raw water flow but gets sucked right into the big hose by the circ pump and then goes in the block, it does not get heated first, only after it gets sucked in.

About the only way to know if thermostat is really open, is to feel the big hose from the thermo neck to the circ pump. When that hose gets too hot to keep your hand on (150*+) then its probably open. I have an IR temp gun and I have taken readings of the intake manifold right under the thermo housing and at 165 on the gauge, the manifold is 155 or so.

Keep in mind that no manufacturer of I/Os or inboards that are raw water cooled ever recommended this procedure, they say to drain manually for FREEZE protection and back fill with AF for CORROSION protection. That's the safest way to do it......
 
Just winterized mine yesterday, and again checked what I wrote above. I let the engine idle about 20 min, till the temp gauge registered a little over 160 . Checked the temp of the big hose from the Thermo housing to the waterpump. Warm, not hot. Thermo most likely not open yet . Water in block was hot when I drained it but not hot enough to open the stat. That's why the suck up the AF method is risky. Take 20 mon longer and DRAIN an poke each drain. Put some OMC or similar gasket sealer on the threads of the drain plugs and they will come right out next fall. Put some marine grease on the necks of the Thermo housing where the hoses get clamped on so they don't rust in place. Back fill the engine and manifolds with -100 AF with corrosion inhibitors if you want to use AF. That is the correct way to winterize raw water cooled engines.
 
I have used the 5 gallon -50 pink run thru the muffs for 14 years on my 99' 5.7 vp and never had a problem. Boat stored in CNY winters inside, not heated, did the same on my mercruiser before that with the same results. Just sayin..
 
Greg, You got the right idea.

Also, depending if you're storing on the hard or leaving in the water, also what type of raw water pick up you have. A 3 way valve would help winterizing.

Drain your cooling system and close the drains. Pour AF from the highest point you want to protect. If from manifolds and risers, fill from both sides.

This is another reason GVP recommended drilling a small hole in the thermostat to purge any air trapped in the system. I drill 2 holes. Turn the engine over a couple times to circulate AF in the raw water pump.

The only reason you need to run the engine is to fog the cylinders.
 
Take out the T'Stats and re lose the housing. . Run the engine for a few minutes and check for leaks. Run pink through the muffs until the exhaust water comes out solid pink. Replace the T'Stats with new next season.

Every couple of years you should be checking the outdrive and all associated wear parts.
 
The bottom hose at the raw water pump was reconnected and the hose clamp tightened before running antfreeze through each engine.
 
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