MerCruiser update

[muc]

SMC-24-03 service bulletin.

Mercury Marine would like to once again stress the importance of using propylene glycol for storage of MerCruiser engines.

Mercury MerCruiser engines require propylene glycol antifreeze in the cooling system for maximum freeze protection during storage in freezing temperatures. Engines must be completely drained of water and then filled with the antifreeze mixture. Drawing the antifreeze mixture through the water pickup will also provide protection to water pumps and some drive components as well.

Mercury Marine offers propylene glycol antifreeze in multiple strengths and quantities. Please refer to the Mercury Precision Parts Accessories Guide to get the right stuff.

Came out last February, I'm guessing they are turning down some warranty claims due to improper winterization.

Just remember the "pink stuff" they sell at the big box stores is for water systems, not for winterizing engines.

 

[alldodge]

If you don't get it all out there is that chance

 

[muc]

If you don't get it all out there is that chance

I don't think it's so much the getting it all out. Cooling water is like engine oil. You can drain it all you want, but when you roll that engine over on the stand --- still gonna have a oil and water mess on the floor --- there is always some left. But, yes the good antifreeze will mix with the bit of water that's left over.

This is why I continue to bad mouth the "pink" antifreeze. Most of it uses alcohol for freeze protection and the cheap ones that do have some propylene glycol in them also still use mostly alcohol. There's a reason for the price.

I think the rust and corrosion are probably more important. I'm in MN and we don't see problems with the single point drain systems on engines that have correct winterization. But I see a lot of people on the internet complaining about that system, I always wonder if it's the water their operating in or poor maintenance?

Some of the better shops here in MN are starting to run the big outboards on antifreeze as part of winterization. Pretty much all the EFI outboards have water cooling the fuel and many (I'm guessing your engines are one) now have some sort of water filter or strainer.

It just makes sense to spend a little money to protect such a large investment.

 

[Chris1956]

If you have a raw water cooled sterndrive, rust will build up in the drains. When you go to drain the block and manifolds, you must dislodge the rust for proper drainage to occur. V-engines have 2 drains on the block and at least 2 on the manifolds. There is also the P/S cooler and the raw water pickup tube and pump/impeller. I would assume the rust would be less in freshwater, vs saltwater.

With a single point drainage system, I would expect some of the drains that feed that system to be clogged with rust.

What the TSB doesn't say is that after you clear the drains of rust, pour a bit of A-F into the cooling water hoses and watch it push out some extra water, before the A-F emerges.

On my 4.3LX V6 engine, I removed the 4 drain plugs, stuck a screwdriver into each drain and waited for the water to drain. Then I poured a bit of a-f into each manifold supply hose, the large recirculation hose from water pump to block and the raw water hose. Antifreeze should emerge from each of the 4 drains and the water intake grates on the outdrive. Now install the 4 plugs and fill the manifolds with straight antifreeze. You should see some drip out the exhaust ports as well as thru the prop. Now fill the block. I would use about 4 gal of antifreeze, which I would drain in the spring and reuse next year.

 

[nola mike]

I'm curious why for many years Mercury didn't require AF for winterization, but then it suddenly became mandatory. I don't think a lack of corrosion in MN is applicable to motors run in salt. I'm also skeptical of the claim that most corrosion happens during layup rather than during the season when warm salty water is being continuously circulated through the engine.

 

[Chris1956]

Mike, I will guess that the single point drain feature started causing more freeze damage, due to clogs of rust in the drains. I say this because I had to poke the drains pretty thoroughly to get them to drain. If you simply open the single point drain, I would expect only partial drainage.

 

[Bondo]

Ayuh,...... I'll continue to winterize my motors, drained, bone-dry,......

Air still doesn't freeze,.....

 

[nola mike]

Mike, I will guess that the single point drain feature started causing more freeze damage, due to clogs of rust in the drains. I say this because I had to poke the drains pretty thoroughly to get them to drain. If you simply open the single point drain, I would expect only partial drainage.

Ayuh,...... I'll continue to winterize my motors, drained, bone-dry,......

Air still doesn't freeze,.....

Yeah, I still suspect that this is merc's attempt to limit user error. The case could be made for corrosion protection, but in a rwc salt engine I think you're pissing into the wind.

 

[Scott06]

Yeah, I still suspect that this is merc's attempt to limit user error. The case could be made for corrosion protection, but in a rwc salt engine I think you're pissing into the wind.

Exactly belt and suspenders, plus it only offers more opportunity to sell more services.

Not sure on the corrosion. Bottom line if you have a way of doing it that works for you stay with it.

I drain , put the plugs back in backfill with a little AF to get any remaining water or water and silt out, drain it and leave the plugs out. This is fresh water only and in the spring the threads in the block would build enough corrosion to require chasing with a tap to thread the brass plug back in. Still leave it dry it worked for years before I started reading how to's on the internet ...

 

[Lou C]

I’ve been telling people around here for years that if they want to use AF West Marine has a page on their site that explains which AF to use based on your climate. Here were we can get to zero, I would not use -50 or -60 in a cast iron engine. I used to use -100 but it is pricey. Last few years I started making my own PG mix of Sierra PG AF & water. 50/50 gives you -26 freeze protection. And about half the cost of premix -100.
Does it help? The eternal debate. I do have a raw water cooled engine run in salt for 20 years. Block & intake haven’t rusted thru yet. Replaced heads 7 years ago I think corrosion is more of an issue for them, perhaps because they get hotter.
In any case if I wind up repowering this boat a half closed cooling system is going on the next engine. I am getting tired of pulling out the rear seats to get at the drains. Closed cooling will make winterizing much easier and you get longer engine life as well.

 

[cyclops222]

If you can afford any NON TOXIC about 35 to 55 gallon drum ? Mix up in it a correct mixture of Anti-freeze solution. REMOVE the prop !!! Run the motor in the A F drum. Until it heats up to correct heat and the thermostat opens fully. Add more A F if needed. Run again to circulate the new A F mixture. We have never lost a engine in over 40 ? years. 1 tank can do everyone's motor.

 

[Scott Danforth]

I use EG on the motor side..... the Raw water side gets drained, and anodes changed every years or so.... and I live in Florida.

 

[nola mike]

Aside from potential toxicity/environmental concerns, why not run EG on the raw side for those inclined to use AF. @Lou C ?

 

[Lou C]

Well that’s the thing you’re gonna spill some no matter how careful you are so I use PG….remember Sierra no tox is good enough to use as an engine coolant

 

[Chris1956]

Gee, storing 4 gal of antifreeze over the season is a drag. I am not storing 35 to 55 gallons of the stuff.

 

[Searay205]

Couple time a year when flushing on garden hose I will open the single drain valve with engine running. It blows the water into the bilge and out the drain. I keep it open for 15 seconds.... Never had issues with blocked drains doing it this way. I usually drain my block at 10:00pm at night with a 40 mph wind. Lunch time its 65f by midnight its 32F welcome to Houston....

 

[muc]

I'm curious why for many years Mercury didn't require AF for winterization, but then it suddenly became mandatory. I don't think a lack of corrosion in MN is applicable to motors run in salt. I'm also skeptical of the claim that most corrosion happens during layup rather than during the season when warm salty water is being continuously circulated through the engine.

MerCruiser has recommended antifreeze for over 50 years, The only years it hasn't been in the manuals was when there wasn't a viable alternative to ethylene glycol and the smart people were starting to realize that we can't keep F ing over mother nature. But they still recommended we use in the schools we attended. The marina I worked for during those years used the polypropylene, I remember because it came in 55 gallon drums and we had to add a dye packet because it came clear. Once the price came down on Polypropylene glycol it was back in the manuals.
It became mandatory when MerCruiser realized they would be dropping GM as an engine supplier, maybe their engineers know something us keyboard warriors don't?
I only mention I'm in MN because I have next to NO saltwater experience and maybe things are different there? But I do have a lot of experience in MN and have found that when MerCruiser engine's are stored full of good antifreeze, they don't have any rust flakes when I drain them down. Only time I had to poke drain holes or mess with the single point drain hoses was when the customer has been choosing low price over quality.
I'm no expert on rust, but I think for the conversion to happen, it requires oxygen. And there isn't much free oxygen when the block is full. So I do guess that most rust happens when the block is empty and just shows up next fall when you drain it. Saltwater? I don't have a clue, but MerCruiser seems to still require it.

 

[Scott Danforth]

maybe their engineers know something us keyboard warriors don't?

I would say yes..... many of them used to work for me.

 

[muc]

Ayuh,...... I'll continue to winterize my motors, drained, bone-dry,......

Air still doesn't freeze,.....

Yes, I understand where you're coming from. And I'm not trying to force anybody to use antifreeze. Your boat-your choice.

But I am asking to STOP and consider those people who are asking for advise. Telling someone with a new MerCruiser engine that they don't need antifreeze during layup is kind of like telling them they don't need a engine oil/gear lube change every year. Will it cause their engine to blow up? No it won't. Could it effect warranty coverage and product longevity? Yes it very well could.

This is kind of like the good vs cheap oil and filter debate. People gonna take a side with out any actual science, just a strong gut feeling.

 

[Scott Danforth]

the issue with the merc manuals is it does not come out and state -100F PG...... so johnny 6-pack grabs -30 RV antifreeze and ends up with a busted block. I pointed that out to a few MC engineers over 20 years ago.....

yes, properly rated PG helps. yes, air does freeze at -471F. however when it comes to winterizing. the merc manuals of yore had the AF as optional. Now to cover their butts, its mandatory. yet, they still do not state -100F PG.