I think I screwed up the winterization process. 2001 5.0 EFI, Alpha1

My engine is a 2001 5.0 EFI with an Alpha1.
For most of last week, the highs in Virginia were around 46 and the lows were around 23, so my boat was exposed to light winds and freezing temps for about 9-14 hours per day for 5 straight nights. I'm guessing that was cold enough to partially freeze the water in the block but not cold enough to freeze it solid.

I picked Saturday to pump antifreeze, the coldest day of the month so far at 38.
Here is what I did:

• set up a plastic tank with 2 gallons of pink -50 marine anti-freeze
• connected ear-muffs and turned on the water
• started the engine, revved to 1000 RPM, and watched the temp gauge
• it took nearly 15 minutes to get up to 170, then it stopped rising.
• after a few minutes it fell to 165, then back to 170, then fell to 165 again, then back to 170
• I assumed the thermostat was now fully open, so I shut off the water and opened the anti-freeze valve
• after a whole bunch of pink fluid spilled into the driveway, I fogged the throttle body and shut off the engine
• I noticed that I still had almost a gallon of pink stuff left in the plastic tank

I'm not feeling real good about this because I barely used 1.1 gallons of anti-freeze and probably more than half of that came out through the exhaust. I doubt whether even a half-gallon stayed inside the engine block. Incidentally, the sterndrive was in the trailer position the whole time.

Here are my questions:

1. How much fluid (anti-freeze) should my engine be able to hold?
2. What did I do wrong, if anything?
3. Could I have a bad thermostat?
4. We're expecting a mild winter in Virginia. Do I need to repeat this process?

You should have drained the motor and manifolds first, then simply poured the AF in.
The way you did it could cause trouble in the spring with a cracked block. Two gallons of AF just fills the block and the manifolds can take 3/4 of a gallon each

Drain the block? How?
Pour it in? How?

Oh boy you have a lot to learn. The way you tried to do it is very bad, unacceptable on raw water cooled engines. There is a drain on each side of the block just above the oil pan and one on each manifold. The you disconnect the bottom of the big hose on the front water pump. Lastly you disconnect the raw water intake hose from the transom at the thermostat housing & hood it down to drain it in the bilge. Poke the block & manifold drains with a pick or coat hanger wire to make sure they drain. It’s things like this that make me hate you tube. There’s a collection of fools advocating that method. If your thermostat doesn’t open all the way long enough the raw water will not exit the engine and one good freeze and it’s cracked. So either learn the right way or have a good shop do it for you but do not wait. Remember the Texas freeze thousands of boat engines ruined.
Sorry to sound harsh but do it yourselfers should use factory shop manuals not the fools at you tube university; with their laziness and ignorance.

^^^----Well spoken in my opinion.

If you posted the engine serial number we can look to see what cooling system you have and post pics for you on the drain locations.

Engine Model number: 4M31027N1
Engine ser # OMO68772

I have made a image and explanation on how to Manually winterize an Alpha Mercruiser. DO NOT SECOND GUESS these instructions. THEY WORK.

These images come from the 2001 5.0 EFI parts listing from this web site.

If you cannot read due to size Send me a private message with your email address and I will email it to you.

Here is what I did:

Click to expand...

Ayuh,..... Unless step #1: is to drain the block, 'n manifolds,....... Yes, you screwed up,.......

Nope,

The drive should be down and level so when you add antifreeze into Incoming water hose (removed from Thermostat housing) to back flush water out thru power steering cooler and out drive with antifreeze

Also with the drive down it self drains any water in the water system

.....

Correction,

""Also with the drive down it self drains any water in the water system""

Having drive down allows DRIVE to self drain all water in the DRIVE system will drain out during winterizing.. Once complete you can trim drive back up if you want.