Drain Block and/or Fill with 50/50 Antifreeze

T

tcontic

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Hi All,

If I drain the block completely of my 2001 Merc 7.4 via the block drains what's the purpose in pumping 50/50 antifreeze through the block?

I can see do one or the other but not sure both

Thank you,
Tom
 
An empty block encourages rust formation inside the passages. Fill it with 50/50, or marine/rv antifreeze.
 
Makes sense.

Would this be a proper procedure for winterizing the block. 2001 Merc 7.4 B3.

1. Warm Engine
2. Change Oil/Filter
3. Open all block drains including risers
4. Close block drains
5. Run to operating temp, thermostat open
6. Switch from fresh water to antifreeze mix on intake to ears on outdrive
7. Wait till antifreeze is observed coming out of cooling system
8. Fog engine till it stalls
9. Done?

Thanks in advance,
Tom

quote:
Originally posted by Msibley

An empty block encourages rust formation inside the passages. Fill it with 50/50, or marine/rv antifreeze.

Click to expand...
 
Don't use a 50/50 mix of standard automotive antifreeze coolant (ethylene glycol). It's toxic and there's not a practical way to recover it from a winterized engine. Use the non-toxic marine / RV antifreeze (propylene glycol)- that's what it's for.
 
Better this way...

1) Warm to operating temp on muffs (or however you want to)
2) Change oil/filter
3) Open petcocks...drain block and manifolds.
4) Remove the hoses from t-stat housing
5) Start backfilling the three smaller hoses one at a time with AF...when you hear/see antifreeze coming from one of the petcocks, close it, and reconnect the hose to t-stat housing
6) Repeat with remaining hoses.
7) Fill the biggest hose last...that's the engine block hose thru the water circulating pump. Keep backfilling til the hose cant take anymore, then reconnect.

You'll use about 4 gallons or so. Much easier this way and does not ingest all the air that those silly "do-it-yourself" winterizing jugs let in.

I've never fogged an engine yet, carbed or otherwise.
 
Clean the block drain holes out with a stiff wire to allow complete drainage. You'll be surprised how much crud comes out.
 
on a FWC engine, do you recommend filling the RW side with anitfreeze, or simply draining?
 
I actually blow compressed air into the block drain holes after draining and running a stiff wire in them. One year, I did the stiff wire thing and filled the block with antifreeze, but it didn't use as much as I thought it should (only about 1 1/2 gallons). So I figured there must be some water still held in the block. I opened the drains again and nothing came out except a few drips; not even the 1 1/2 gal. of antifreeze I just put in. That's when I blew the compressed air through the drain and lo and behold, a whole lot of water and antifreeze came pouring out. After closing the drains and refilling again with antifreeze, it took almost 4 gallons. I figured I did the right thing and didn't have a cracked block in the spring. Now I just blow the air in to make sure I've loosened anything that could plug up the drains.
 
Absolutely fill the RW side of a FWC system with anti-freeze. Much easier to winterize FWC engines than RWC. The block is already full of antifreeze so you don't need to worry about the thermostat being open. Just run a couple gallons of antfreeze thru and you're done.
 
Mike, on my 5.0 merc. 1999, i have 4 hoses total, 2 manifolds, 1 main block and 1 is the water intake from the drive.
If i fill this hose whit AF till it comes out the drive am i OK??
 
Should be OK, I drain the water intake hose for my Cobra by disconnecting it at the thermo housing and then pointing it down in the bilge, that drains the hose. If there is a P/S cooler inline with that hose, you can take out the drain plug to be on the safe side. I then fill that hose with AF, it will start running out the water intakes of the drive, so you can't fill it all the way, but that will get AF in the impeller housing and push out any remaining water. I fill the engine from the big hose in the front (disconnected on the thermo end, connected on the engine water pump end) till AF comes out the thermo housing, then reconnect. I fill the manifolds thru the hoses the same way, till I hear AF run out on the ground. By the way that is why you need to use no tox AF, regular AF is very poisonous to people and animals. Takes about 5 gal total to do my 4.3. I think adding the best -100 AF helps reduce corrosion in cast iron.
I would not use any of the suck up the drive kits, for a raw water cooled engine. That can work for the raw water side of a closed cooled engine, but I still prefer to drain and backfill.
 
Adding antifreeze ensures that the engine is protected. After draining the block there will be some water left in it. Will it be enough to crack it? I don't know and have never taken a chance. I fill all the hoses. Both engine and exhaust. Spending $20 today is a lot cheaper the $2000 come spring
 
I never bothered blowing out the RW side and always used a non-toxic automotive AF like Sierra cut 50/50 with cheap windshield washer fluid. Provides increased freeze protection and corrosion protection but still is non-toxic so it can be disposed of easily in the spring. All of our I/B engines were closed cooling systems so it was a simpe task of putting the end of the RW intake hose into a 5 gallon bucket of solution and running each engine for a minute or so until we saw the solution exiting the exhaust. Then, shoot fogger into the air intake until the engine stalls. Done.
 
I never used the antifreeze until last year and I worried about it all winter due to the fact that the stuff will gel. If I were doing it over I would drain the water, blow the air through the block from both block drains (always did this) and then run the pink stuff through. Only change in that sequence would be to then drain the pink stuff as well.
 
The safest way is to drain the block and fill the hoses with AF. If you try and pull in AF via the cooling system, you must be positive the T-stat is fully open and even then its a mixing situation.

Its always a good idea to poke a nail or small screwdriver into the drain plug hose to pop out rust. If water come out, you need to keep doing it until nothing comes out.

But the real test is being able to add what you know is the correct number of gallons of AF to the block via the hoses. If your block takes 2 gallons of AF, then when you have poured in 2 gallons of AF you are done. There were no pockets of water blocked by rust.

If people who winterize by muffs and a bucket of AF would try draining and filling the block one, they would never go back.
 
For example, if yout T-stat happens to malfunction and does not open properly during winterization you will still have mostly water in the block and there goes a $2000 or more engine. Your temp gauge will still show the engine is warmed up, just that the water is circulating within the engine and not mixing with any cooling water. The temp gauge will start to climb, but may not be noticed during the short timeframe of mixing in the AF solution.

If I winterized pulling in AF, I would drain some AF into a Dixie cup from each side of block and pop into freezer to see if it frooze.
 
DD. if those who run on muffs with anti-freeze would check the mixture in the block, there would be a lot of worries all winter if they realized just how dilute the mixture can be in the blocks!
 
I agree, but I would not be one of them. But the irony is that draining the block and filling via hoses takes less time and uses less AF to achieve a better result.

Also I think its also impossible to run the engine on muffs sucking up AF while at the same time trying to stall the engine with fogging oil and timing all of this so it works out.
 
Agree 100%. I always run about 3 gallons of full strength antifreeze thru each engine as soon as the boat is hauled and engines still up to operating temp. That way, I know the raw water pumps, oil coolers, manifolds and exhausts are covered. I then check the mixture in the block and always find the block mixture is so dilute that I'm only good to 0 degrees to 10 degrees above. A really watered down mixture. Then I drain the blocks down and re-fill with 50/50 and sleep well all winter.
 
I always just drain and back fill with -100. No worries about AF running out when you are fogging and no worries about the impeller not sucking up the AF. I really don't get why people are so stuck on trying to suck the AF up the drive. It isn't that hard to remove the drain plugs manually like you are supposed to. One of the firs things I'd look at when considering buying a boat, is how easy it is to get at those plugs. If you never remove them, and then one day you have to, you could be in for a nasty (rusty) suprise.
 
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