Winterizing Mercruiser 4.3 question

[Maverick7]

Watched a bunch of videos on YouTube and thought I had this winterizing thing figured out. However, I realized after watching that my engine differs slightly from those that I have watched. I have attached a picture of my engine, it has an extra set of hoses going into a “T” on top of the thermostat. On the videos I was watching, this was absent from those engines. Just wondering what exactly this “T” is and if I need to do anything special as far as winterizing.

Secondly, I bought a winterizing kit from camco, basically just a big jug you fill with antifreeze, and it comes with a hose to connect to the muffs. However, in the directions it says not to use if you have a front engine mounted seawater pump. Not sure if this applies to me or not.

my plan for winterizing was this:

1. Connect water to muffs and place on drive
2. Run engine up to operating temp
3. Switch over to antifreeze and run engine on antifreeze
4. once pure antifreeze is coming from exhaust, fog motor until it dies.
5. Pull all drain plugs on engine block and drain antifreeze, then reinstall plugs.
6. Fog spark plug holes, reinstall spark plugs

And of course do oil, drive lube, filters, etc.


This is my first year with an onboard/outboard, so the learning curve has been drastic.

 

[Rick Stephens]

I think you are guaranteed to leave a big ol pure water pocket in the engine and crack your block that way. You must drain completely before adding antifreeze. I skip that and just drain everything and leave it open. I'm one of those 'air don't freeze' guys. Nothing wrong with using antifreeze, but if you push into warm engine it will go into the thermostat housing and 99% bypass right out the exhaust. Engine will not get much antifreeze at all as the thermostat isn't going to be open when not under load and an endless supply of cold water.

 

[Maverick7]

I think you are guaranteed to leave a big ol pure water pocket in the engine and crack your block that way. You must drain completely before adding antifreeze. I skip that and just drain everything and leave it open. I'm one of those 'air don't freeze' guys. Nothing wrong with using antifreeze, but if you push into warm engine it will go into the thermostat housing and 99% bypass right out the exhaust. Engine will not get much antifreeze at all as the thermostat isn't going to be open when not under load and an endless supply of cold water.

I guess I’m not picking up what you are putting down here. Sounds like we are saying the same thing. Ultimately I would drain the engine, and it would be empty of water and antifreeze. The point of running the antifreeze would be to push it into anyplace that isn’t going to completely drain by pulling the plugs.

 

[Bondo]

I guess I’m not picking up what you are putting down here. Sounds like we are saying the same thing. Ultimately I would drain the engine, and it would be empty of water and antifreeze. The point of running the antifreeze would be to push it into anyplace that isn’t going to completely drain by pulling the plugs.

Ayuh,...... The process starts with drainin' the block, 'n manifolds 1st,......

If you then wish to run antifreeze through it, 'n drain it,.......... Go for it,......

 

[Scott Danforth]

too bad the correct process wasnt in a manual......wait......it is

change engine oil and filter
change fuel filter
run to verify no leaks

drain water from block, manifolds and intake t-stat cross-over
probe drains
pull large hose and drain
pull hose to outdrive and PS cooler and drain

you are now winterized

in the big "optional" section
then if you want anti freeze, use a funnel and fill from the thermostat housing

 

[muc]

https://www.mercurymarine.com/en/us/faq/?category[]=mercruiser-corrosion&category[]=mercruiser-maintenance&category[]=mercruiser-winterization

QUESTION:

Do I need to put antifreeze into the raw-water/seawater section of the cooling system after draining?

ANSWER:

MerCruiser requires the use of propylene glycol antifreeze (with a rust inhibitor for marine engines) in the seawater section of the cooling system. Damage caused by freezing or improper winterization is not covered by the limited factory warranty.

QUESTION:

Do I still need to have winterization performed by my dealer if I have a self-drain system on my engine?

ANSWER:

The drain system on your engine is NOT intended to replace full winterization. It is for extending your boating season by allowing the cooling system to be drained after use if there is a risk of light freezing weather and you will be boating the next day. For full extended winter storage, after completely draining the cooling system, Mercury MerCruiser requires the use of propylene glycol antifreeze (with a rust inhibitor for marine engines) in the seawater section of the cooling system. The fuel system must have fuel stabilizer added and the system must be fogged with 2-cycle oil. We recommend that your product be winterized by an authorized MerCruiser dealer. Damage caused by freezing or improper winterization is NOT covered by the limited factory warranty. This is also a good time to have scheduled maintenance performed on your engine by your dealer.

 

[Lou C]

I’ve been simply draining everything as per the manual and then backfill with PG to reduce corrosion not sure if it really helps but in salt water you need all the help you can get.

 

[tpenfield]

to answer your question about the "T" fitting on the thermostat manifold . . . that looks to be the hoses that go straight to the exhaust riser/elbows.

Water comes up to your engine from the outdrive (I assume it's an Alpha) . . . goes the the T-stat housing, goes through the engine block, then goes to the exhaust manifolds, goes up the riser/elbows and out the exhaust. The lines coming from the "T" fitting are a secondary flow to make sure the exhaust has cooling water immediately, and not totally relying on the water that went through the engine, which will be hotter than the incoming water.

If you use the jug-kit approach, keep in mind that a fair amount of the AF that goes into the engine will go up out the "T" fitting directly to the elbows and never go through the engine. That is why you see the pink liquid coming out the exhaust fairly quickly. It has not gone through the engine.

Also within the engine the AF that goes to the engine block will 'mix' with the water that is there in a diluting fashion. Your engine probably holds about 3-4 gallons of water (including the exhaust manifolds) so it might take 8-10 gallons of AF to fully purge the water from the engine. Most folks run 4-5 gallons and call it good. But about 1 gallon went straight out the exhaust, and 3 gallons mixed with the water in the engine making it about a 50% concentration of AF & water.

That is why draining is so important, and a preferred method is to drain the water while the engine is hot, then run the AF.

 

[AMMO DAWG]

too bad the correct process wasnt in a manual......wait......it is

change engine oil and filter
change fuel filter
run to verify no leaks

drain water from block, manifolds and intake t-stat cross-over
probe drains
pull large hose and drain
pull hose to outdrive and PS cooler and drain

you are now winterized

in the big "optional" section
then if you want anti freeze, use a funnel and fill from the thermostat housing

Thanks, was actually what I was looking for. Does pulling the plugs on the block drain the intake or is something additional done? Sorry to hijack the post.

 

[nola mike]

https://www.mercurymarine.com/en/us/faq/?category[]=mercruiser-corrosion&category[]=mercruiser-maintenance&category[]=mercruiser-winterization

QUESTION:

Do I need to put antifreeze into the raw-water/seawater section of the cooling system after draining?

ANSWER:

MerCruiser requires the use of propylene glycol antifreeze (with a rust inhibitor for marine engines) in the seawater section of the cooling system. .

When did this start? Manual #7 doesn't mention it, #18 and 25 "recommend" it.
@Maverick7 , removing all the drains and hoses will drain the block and manifolds completely. If adding a/f, Merc recommends removing the thermostat and adding through the tstat housing.

 

[louc]

1) if this is a Vortec V6 (intake has 8 bolts holding it to the cyl heads instead of 12) there is an additional drain plug on the front surface of the intake that needs to be removed to prevent freeze damage. This was not present on the older ones like my ‘88 4.3.
2) its not necessary to remove the t stat housing to fill with AF, simply reconnect the bottom end of the big hose at the circulation pump, and disconnect the top end. Put a funnel in the top end and start filling with AF till it spurts out the neck of the t stat housing that the big hose was connected to. Reconnect hose & done. Fill exhaust manifolds same way till AF runs out the exhaust housing in the transom mount.
3) I like to put the drive down, disconnect the raw water feed hose at the t stat housing and then fill that hose till AF runs out the water intakes of the outdrive. That pushes water out of that hose and any coolers in line with it and the impeller housing in the outdrive.

 

[muc]

When did this start? Manual #7 doesn't mention it, #18 and 25 "recommend" it.
@Maverick7 , removing all the drains and hoses will drain the block and manifolds completely. If adding a/f, Merc recommends removing the thermostat and adding through the tstat housing.

I'm not sure when anti-freeze became required. High quality marine service providers have been doing it for decades so I really didn't pay much attention when MerCruiser made it official. My guess is that it was around the time they were designing the single point drain system and realized there would be problems with engines that weren't properly maintained.

Manual #7 was written in 1982. #18 in 1992 and #25 in 1997. Even back in 1963 they started the manual with these words.

.This service manual has been written and published by the Service Department of Mercury
Marine to aid our dealers’ mechanics and company service personnel when servicing the
products described herein.
It is assumed that these personnel are familiar with the servicing procedures of these products,
or like or similar products manufactured and marketed by Mercury Marine, that they
have been trained in the recommended servicing procedures of these products.
We reserve the right to make changes to this manual without prior notification.
Refer to dealer service bulletins for other pertinent information concerning the products described
in this manual.

So we can see that all of these manuals were outdated when they came off the printing press. And they are written for mechanics who have been trained and have access to the service bulletins.

MerCruiser hasn't recommended removing the thermostat for many years. We suck it up through the muffs, that way it fills the entire system. Or do it like @Lou C and pour it in many different hoses. Just remember that won't work very well on the new systems.

 

[louc]

I think the debate about does AF really reduce corrosion in storage will go on forever just like oil threads. I do it because in a salt water region you are always dealing with corrosion, it never stops. My reasoning, it keeps out oxygen and you need oxygen for rust. Just like coating trailer leaf springs with grease/oil/corrosion X or similar. I recall I changed the springs on my old trailer about the same time my neighbor bought a new boat. The marina maintained hers and no one ever put anything on the springs. About 5 seasons later hers looked like they had to be replaced right then, mine still looked good. I've been getting approx 10 years out of a set of springs doing this.
One thing for sure, if I put in a reman or new engine there is no way I'd leave it raw water cooled. The first things I'd add are closed cooling and a remote oil filter mount. That makes having an I/O here tolerable for the do it yourselfer, otherwise as you get older they become an incredible pain.

 

[QBhoy]

As said above. This debate will go on forever. But what ever you decide. Do not use the idiot YouTube flushing from muffs method of winterising. These are the smart ass guys that you never hear from again...because they are too busy looking for a new engine block the year after.
either drain completely and leave it..and suffer internal cold corrosion for years to come...or drain completely and fill with AF at the t stat to stop any corrosion. If it’s not been done like this from day one...may not be worth it with the damage already done and having to constantly clear bits of rust from the drains each year. Up to you.