Single point drain

[ZafSC]

Hi folks,
Planning to winterize my engine the first time. Actually, I was going to give it to a marine shop (I'm in NH), but all the shops are fully booked until November and it will be freezing on next Sunday night, so I guess I have no option other than DIY.
It is a MerCruiser 5.0 MPI. After watching some videos, I assumed there are multiple blue plugs under the engine, but I found only one on the front bottom. (see picture) How can I be sure that is the case? (It is extremely difficult to see under the engine, because starboard there is heat exchange, and port side there are batteries. I had to use a selfie stick to take pictures)
Thanks

 

[alldodge]

In most cases there is also plugs on the raw water pump or there is air valves

What is your motor serial number?

 

[ZafSC]

Attached are the serial numbers.
I am worried that when I drain thru this plug, I might not be able to drain all the water in the engine. Is there any way to verify that?

 

[Lou C]

We need more information about your cooling system, you mention a heat exchanger, if there is a closed cooling system on this engine, then the block does not have to be drained since it should be full of antifreeze, but the raw water side has to be drained, and if the manifolds are on the raw water side, they do need to be drained as well.

 

[Bt Doctur]

If you collect the water coming out you should catch about 4 1/2 gallons. But to be sure you need to unhook the quick disconnect fittings at the block to verify complete draining. Sometimes they get clogged
and you need to probe the fittings to insure there not clogged with scale/rust/sediment.
manifolds/risers/inlet hose/manifold hose/raw water pump



should drain from the blue plug. I try to remove this system permanently by installing the block drains with the blue plugs and the manifold drains with the blue plug .The small drain hoses get removed
,the block hoses get removed .You can cap them at the drain manifold or simply loop them or just cap them.

 

[ZafSC]

No no, it is not a closed system. It takes the cooling water from the lake. (I guess it means open cooling, right?). I took it the shop last year and after that I made sure pink water came out from the plug above. And for the heat exchange and all the fresh water, I did it myself by putting lighter pink into the fresh water tank.
My question is straightforward: How can I make sure all the cooling water (I guess it is called raw water) is fully drained so that it doesn't freeze.
Thanks

 

[alldodge]

Not what you want to here but there are a few variables.

With open cooling and single point drain you should have a blue plug on the thermostat housing. Either that or will have a small air pump mounted on it.

The drive comes up as a A G2, so there is no worries with the raw water pump

The way it should work is pull the plug, drain and then refill with AF

 

[ZafSC]

Not what you want to here but there are a few variables.

With open cooling and single point drain you should have a blue plug on the thermostat housing. Either that or will have a small air pump mounted on it.

The drive comes up as a A G2, so there is no worries with the raw water pump

The way it should work is pull the plug, drain and then refill with AF

Allright, that does it ! When I open the round valve, water comes out abundant on the orange outlet in my initial post. Clearly that should be the main drain point. Now some questions for the remaining work:
1) What is the use of the blue tap/plug on the thermostat (left one on the picture), is it relevant? Similar question for the tap/valve at the bottom.
2) I will drain all the water and fill with AF as you suggest. Which hoses should I use for refill? (See picture, I numbered them) Does that guarantee that there is no water left in the engine?
3) If not, should I feed extra AF from the muffs on the drive while running the engine and watch the pink comes out of exhaust, just to be on the safe side? (Or this step is totally unnecessary?)
Thanks

 

[alldodge]

The plug on the thermostat housing is to open an air way so the water flowing out goes easy and there is a reduced risk of a vacuum happening and it holding some water back. It gets removed first before lower plug is removed and valve is opened

If all the water is out your safe, but if any of the drain lines are plugged up and don't drain, then there is a chance of freeze damage. Pouring AF in after draining is a way to help mitigate the possibility.

AF issues, and note this is MY Opinion, others vary:
Green stuff is toxic to animals but when mixed with water it's good to below zero

Pink stuff is non-toxic, made for water systems but when mixed with water the burst rating is reduced

Blue AF is non-toxic and helps protect against rust and corrosion and when mixed with water is same as pink

Air doesn't freeze but does not protect against rust, and if in salt water would highly recommend using Blue AF. If 90% is water is out then any water left behind if not fully confined will freeze and expand but will not break anything.

What you need is the owners manual for your motor. The manual tells you exactly how to winterize
Look HERE and find the one for your motor

 

[ZafSC]

Thank you for the manuals link. It will need some digging, many items about 5.0 MPI.
Could you answer my questions 2 (hoses) and 3 above, if possible?
And about the heat exchanger (see attached picture), will the antifreeze naturally fill the hoses and the heat exchange with gravity?
Thanks a lot in advance..

 

[alldodge]

Pour AF in hose 2, it won't be completely fill everything, but will be real close

Don't know the heat exchanger is used for, warm air or hot water?
Is it connected to the motor or something else?

Look on the HE and does it have a drain valve? If not remove both hoses

 

[ZafSC]

Heat exchanger is for the hot water (see picture). The right side hoses come from the engine. The left side is fresh water (faucet, shower etc..). It needs to be winterized separately. Last year I did the left side (fresh water), used potable antifreeze. The shop told me when they did the engine, the right side was done as well. So my question is, filling up the AF thru hose 2 sufficient flow for the heat exchanger?

 

[alldodge]

That is a hot water tank and looks like it is only heat by electric. If it's heated by the motor as well then the lines need to be drained. There is a valve on the tank when opened will drain the tank.

Once drained you can fill and pump RV AF thru to all parts but what I do is connect the in/out lines together. Put AF in water tank and pump it thru the lines, otherwise it will take a few gallons just to fill and move thru water tank

 

[ZafSC]

If you collect the water coming out you should catch about 4 1/2 gallons. But to be sure you need to unhook the quick disconnect fittings at the block to verify complete draining. Sometimes they get clogged
and you need to probe the fittings to insure there not clogged with scale/rust/sediment.
manifolds/risers/inlet hose/manifold hose/raw water pump



should drain from the blue plug. I try to remove this system permanently by installing the block drains with the blue plugs and the manifold drains with the blue plug .The small drain hoses get removed
,the block hoses get removed .You can cap them at the drain manifold or simply loop them or just cap them.

Doctor, is the plug on the picture the "quick disconnect fitting"? I found it on my engine (see picture) as well. Does it have the same function as blue manifold? I mean they are supposed to be out for draining as well?
What is the difference between block drains and manifold drains? As I mentioned, I cannot see any blue manifolds under the engine. I only see two of them, one at the bottom of the engine (my first picture) and one on the thermostat. (Mentioned in this thread).

 

[tank1949]

I'd ditch the blue plastic crap and replace with 2 brass or SS. My ss ones came with o-rings. Most Chevy V8s have block side drains, usually a brass pipe threaded plug (one each side ). Mine have drain cocks but are very difficult to access. Yours will be too. However if you drain and go back with drain cocks, life will be much better for you later one. Of course disconnect all water inlets.

 

[ZafSC]

Ok, after draining the water using the round valve in the picture on my #8 post, I removed the thermostat block (only two screws, easier than removing the hose), I poured down 3 gallons of antifreeze and it looks full now.
1) Is it supposed to be 4.5 gallons? Where is the remaining 1.5 gallon?
2) What about the water left in the power drive (around exhaust, impeller etc). Did the AF go there as well? How can I make sure?
Thanks

 

[alldodge]

Water in the drive drains out on it's own.
The 4.5 gal includes the the exhaust manifolds, and hoses, and some parts just drain back out

 

[ZafSC]

Water in the drive drains out on it's own.
The 4.5 gal includes the the exhaust manifolds, and hoses, and some parts just drain back out

Sorry, not clear. So there is no water in the drive that I should worry, no need put antifreeze there?
I checked the quick release disconnect on each side of the engine block, and AF came out nicely.
So, is it all done? No need to run the engine and suck more AF thru the muffs?

 

[Lou C]

Does the engine have power steering and/or a fuel cooler? If so they may need to be drained unless the one point drain also drains them which should be the case.
My brother’s 2020 Merc had this set up and when we filled it with -100 AF after draining the AF filled the engine & came out the water intakes on the outdrive.
If he still had this boat (traded it on an outboard) I advised him to measure how much water drains that way you can tell if it’s starting to clog. Here in salt water it’s just a matter of time, when that happens I’d think about removing it.

 

[alldodge]

Sorry, not clear. So there is no water in the drive that I should worry, no need put antifreeze there?
I checked the quick release disconnect on each side of the engine block, and AF came out nicely.
So, is it all done? No need to run the engine and suck more AF thru the muffs?

Yes on all questions

PS cooler is on rear of motor and self drains with rest. Fuel cooler is connect with single point