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Old 10-02-2021, 09:45 PM   #1
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Default winterizing '91 2300 SCR

Much as we hate to see it go, summer is gone and this is ourfirst winter with our new boat. I have winterized others boats before & have been looking through the mercruiser manuals, but . . . Does any one have a list of must do on the mercruiser 5.7 alpha? I will blow out the water system in the boat (air can't freeze), just would like someone elses take on engine must do. It is a closed system so,must do risers, heat exchanger, power steering cooler, fresh water intake, and what else am I missing? Thanks in advance!

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Old 10-03-2021, 11:34 PM   #2
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Add stabilizer to the fuel tank and run the engine to get it trough the system. Fog the engine. Change oil and filter. Change gear lube. Change fuel filter. Flush engine with hose water then drain HE, elbows. Since you have an Alpha I would use a winterization kit to pump antifreeze into the raw water pump displacing any water in it.
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Old 10-04-2021, 05:47 PM   #3
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Save yourself a lot of time and just run the antifreeze through the outdrive on muffs. I used to use a garden hose splitter. Run the single to the muffs. A garden hose goes to one side. A short hose into a 5 gallon bucket full of antifreeze.

Turn on the garden hose and start the engine. Once the water is existing the exhaust, open the valve to the anti-freeze and close the valve to the garden hose. You'll need to stand by and continue filling the 5 gallon bucket while the engine is running (I would have a case open sitting handy, plus a few more unopened just in case.).

Once solid pink is coming out of the exhaust, shut down the engine. You've now just winterized the outdrive, the heat exchanger, and all the passages where raw water flows.

As for the "Air Don't Freeze". That is a very common adage by a small number on a variety of forms. There is no guarantee you'll get all the water out, or that it won't collect at a low point, freeze and expand. That low point will almost always be where a fitting is located.

Bypass the water heater, drain the water heater and pump pink AF through the system.
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Old 10-06-2021, 04:34 PM   #4
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Thanks for your input, I like your approach! Does that replace opening all the drain plugs on the risers etc? Or do I drain them and then run the pink through the system?
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Old 10-10-2021, 05:43 PM   #5
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Thanks for your excellent advice Shrew! I got the kit to do the pink antifreeze flush. It was perfect! Project done . . . .
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Old 10-10-2021, 11:36 PM   #6
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Quote:
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Thanks for your excellent advice Shrew! I got the kit to do the pink antifreeze flush. It was perfect! Project done . . . .
Before adding the antifreeze did you run the engine long enough to ensure it was warmed up the the thermostat open? If not the antifreeze bypasses going thru the engine. You can remove the engine drain plug on the lower port side of the block. If antifreeze starts coming out reinstall the plug and your done.
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Old 10-11-2021, 02:15 AM   #7
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Hey Mike,
Yup, ran it till the thermostat opened and checked my manifold drains to make sure they had pink in them. All is good. Gonna get down in the mid 20's next couple of nights here in North Idaho, stand by here comes winter . . . .
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Old 10-11-2021, 12:49 PM   #8
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Hey Mike,
Yup, ran it till the thermostat opened and checked my manifold drains to make sure they had pink in them. All is good. Gonna get down in the mid 20's next couple of nights here in North Idaho, stand by here comes winter . . . .
Yikes to cold for me.

The manifolds are not impacted by the thermostat position and always get coolant. Since you ran it till it warmed up you should be ok but this has been a big mistake made by many resulting in a cracked block. Again an easy check is to pull the block plug to verify.
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Old 10-11-2021, 09:51 PM   #9
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where is the block plug? found it, don't think it has ever been opened. rusty and won't open
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Old 10-12-2021, 11:45 AM   #10
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where is the block plug? found it, don't think it has ever been opened. rusty and won't open
Another option is to loosen the circulating pump hose to see if antifreeze is in it.
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