Winterization Question

Golflover

Seaman
Joined
Sep 10, 2009
Messages
51
WHAT: I am winterizing my 6.2 L MPI MX Mercruiser for the first time. It has 3 blue plastic, wing nut style, drain plugs and 1 blue plastic vent plug up top near the thermostat. Of the 3 drain plugs; one is easy to access and is centrally located on the lower front or fore side of the motor. The other two are close to each other, down low on the starboard side.

PROBLEM:, I can only see those two with the help of a mirror. While I can contour my arm to touch one of them by hand, I don't have the leverage to spin it off. The other one I simply cannot reach. I entertained getting an extension tool to try reach them, however, my:

MY CONCERN arose when I tried to remove the upper vent plug it broke off, leaving the threads inside. The engine heat and metal, over time, seemed to fuse the materials together. Because this plug was easy to access, I was able to clear out threads enough to replace the plug, however, it took over an hour.

MY FEAR, if I broke one off one of these lower plugs where I couldn't access it I would have to pull the motor to fix it.

QUESTION: If I flush the block with non-toxic anti-freeze and can't pull all three drain plugs after doing so, am I in danger of damaging the block or is this sufficient as a replacement to pulling all the drain plugs? I live in Michigan and it gets cold.

Also, I have read somewhere that fogging this motor is not recommended, it this true?

Any help would be appreciated.
 
Last edited:

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
47,296
There are no shortcuts here. Open the drains and drain the block. Pulling the motor would only take an hour if needed. However its less expensive than broken block from a Michigan winter and a a poorly winterized motor
 

DeepBlue2010

Lieutenant
Joined
Aug 19, 2010
Messages
1,304
what type of cooling you have, open or closed (a.k.a fresh water or raw water cooling)? Last season, I came across some guy in my Marina who was asking a similar question and when I jumped in the engine compartment to help him, I found a fully closed cooling system on the engine. I then explained to him that he doesn't need to do that for his specific engine but he insisted he does because he "watched the video on youtube"
 

tlewis1

Petty Officer 2nd Class
Joined
Oct 9, 2012
Messages
112
The blue plug you broke at the top of the t stat housing is very common to break. I have pulled hundreds of plugs down low on the stb side and never broke one from in the plastic housing. I agree with Scott, they're no short cuts to be taken when winterizing. Although on many boats the plugs seem almost impossible to get out I have always managed to get at them some way.....

I would recommend if this is your boat and you plan on winterizing every year in the future, you make the plugs accessible in a way that every fall they are easy to get at.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
QUESTION: If I flush the block with non-toxic anti-freeze and can't pull all three drain plugs after doing so, am I in danger of damaging the block or is this sufficient as a replacement to pulling all the drain plugs? I live in Michigan and it gets cold.

Also, I have read somewhere that fogging this motor is not recommended, it this true?

Any help would be appreciated.

You actually can "flush" the block with any anti-freeze but YOU MUST remove the thermostat and then replace the thermostat housing so you can run the engine.

Disconnect the manifolds and risers from the cooling system (completely & drain them) and set up a "closed" cooling water system with the block, heads, circulating pump and engine driven raw water pump (this is a Bravo right?)

If it is a Bravo, disconnect the transom raw water hose to the raw water pump and connect another hose to run to your AF container.

Connect the 2 hoses to a that went to the exhaust manifolds to a "Y" and run the Y (single) hose to your container (that's your discharge) Get a large enough container so you can pour the amount of AF in the container that equals the amount of water remaining in the block.

THEN, run the engine to circulate 100% AF through the entire cooling system for long enough to mix thoroughly with the water already in the block. The discharge WILL be the AF and water in the block that mixed

After you're sure the AF has thoroughly mixed with the water left in the block, drain some and test for concentration. You want roughly 50:50. If it's less, add some 100% to the container and run the engine long enough to mix it.

Essentially, you'd be "creating" a closed cooling system............. removing the T-stat allows for immediate mixing............ disconnecting the manifolds and risers keeps you from dumping the mixture overboard. You would connect the hoses that were connected to the exhaust manifolds as your discharge back to the AF container where you would place your raw water "pickup" TO the raw water pump.

If you have an alpha, (raw water pump in the drive), you could use a larger container (tub) and ensure that the level of the AF was at least up to the level of the raw water pump impeller so it would prime......then run the Y-connected manifold hoses back to that container so you could collect the discharge.....

Running the engine while doing this allows the (engine) coolant circulating pump to circulate the ensuing mix through the block and heads.

After doing this, you would still need to ensure that the manifold/riser assemblies are thoroughly drained too.


/////////////////////


All of the above would be quite time consuming.........And would absolutely take longer than just removing the drains to drain the block properly!!


AND certainly longer than fixing the "problem in the first place! If it were mine and I needed to pull the engine to "re-do" [drill & tap] the drains and replace the plugs, I would do it!

Fogging an MPI engine is not recommended because you can damage the intake sensors (MAF, temp etc....)

If I didn't have closed cooling on my 454, I would drill/tap my drains to the next size up and install brass reducers and brass plugs.


Regards,


Rick
 

Golflover

Seaman
Joined
Sep 10, 2009
Messages
51
Thanks for all of your input. I have a Bravo 3. The cooling system is an open (no coolant) system.
 

Golflover

Seaman
Joined
Sep 10, 2009
Messages
51
Tiewis1---." I have pulled hundreds of plugs down low on the stb side and never broke one from in the plastic housing." So you're saying that other than the vent plug up top, those other 3 are threaded into a plastic housing and therefore there is little likelihood that they will fuse like the one into metal?
 

tlewis1

Petty Officer 2nd Class
Joined
Oct 9, 2012
Messages
112
Ya that would be my thought on why they do not break in the plastic housing. I run a marine shop in Northern Canada so we do allot of winterizing this time of year. That top plug in the t stat hsng is always a bugger and almost always need a pair of pliers to pull.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,464
QUESTION: If I flush the block with non-toxic anti-freeze and can't pull all three drain plugs after doing so, am I in danger of damaging the block or is this sufficient as a replacement to pulling all the drain plugs? I live in Michigan and it gets cold.

Also, I have read somewhere that fogging this motor is not recommended, it this true?

Ayuh,..... If ya insist on antifreeze, ya still Drain everything 1st, not after,....

Air Don't Freeze,.....

I don't fog, unless a year or more is the expected lay-up,...

As for the blue plugs, Ya, I find the wings rot, 'n get brittle,....
Usually, I can rip 'em out with channel locks, or vise-grips, 'n put in a new one,...
It makes sense the one on the top of the motor breaks easier, it sees more Sun,....

If the o-ring is good, just snug 'em,...
Folks thinkin' they gotta be super Tight, cause broken wings too,....
 
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