Draining a Merc 3.0L

Condor1970

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Jun 9, 2014
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Ok, I've decided it's probably easiest to just drain the block when winter hits here for winterizing, because in the Seattle area, we don't get the super cold winters seen in the Midwest. I really see no reason to use anti-freeze, as it will only be winterized for a few months before the spring then hits, and the boat goes back in the water.

So, does anyone have a pic or video description as to exactly how to properly drain the block on a 3.0L?

I see a brass fitting on the port side of the lower block in the bilge. I don't see any actual valves, like pet-cocks. Just a brass fitting that requires a wrench. It has a hole in it, like it would be a tubing fitting or something. Is this the drain?

If so, do I need to do anything else, like blow air through the system somehow to dry the inside of the water channels?
 
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thumpar

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That is one drain. There should be one in the exhaust elbow or riser also. Take the lower hose off the water pump to drain it too.
 

airshot

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Jul 22, 2008
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Be sure your outdrive leg is down so the water drains from that as well. I remove my leg for the winter which allows me to look inside and check gimbal bearing and look for any leak signs. Best for the bellows if stored down so no stretching is done during storage. When you remove the drain plugs from engine and manifold use a wire to poke the holes to be sure their is no blockage and all the water drains out.
 

Condor1970

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Jun 9, 2014
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That is one drain. There should be one in the exhaust elbow or riser also. Take the lower hose off the water pump to drain it too.

That skinnny hose is really hard to remove on mine....

Can I remove the larger hose on top on the starboard side of the engine, instead?
 

Starcraft5834

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Jun 2, 2013
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Condor.. you should have (2) points to drain... back right side low,, block petcock drain screw.. pull that and drain it.. other one should be above that on same side...manifold drain screw, unscrew that and drain it.... then take a air compressor, remove water hose on top and blow away... that will drive out 99% of the water in there,,,what ever is left wont matter.... if your stored outside, remove drain plug and leave out... do your other fluids, wrap her up nice, it will sleep very well all winter empty... I live in the north east.. last winter we had (15) days in January that were below zero... I had bought my first mercruiser and asked about winterization, Bondo told me to drain it and forget about the pink stuff,,, I did that and it ran perfectly.........pink stuff is a waste of money in my view...cast iron and empty get along just fine....
 

Bondo

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That skinnny hose is really hard to remove on mine....

Can I remove the larger hose on top on the starboard side of the engine, instead?

Nope,.... No skinny hose, pull the BIG hose off the circulatin' water pump,....
If ya don't have 1, invest in a Hose Pick,...
A cheap tool, I can't live without, it helps remove Any hose, regardless it's size,...

The Block drain is down low, mid-way, portside,....
The Manifold drain should be just above it, upside-down on the manifold,...
If ya got an older motor, with the squareish riser, it has drains on each side, aft lower corner,... pull either 1 you can get too,...
If a newer motor with the roundish riser, No drain,....
No compressed air is necessary, gravity will drain it,....
'n if ya got P/Steerin', the cooler needs either of the Big hoses pulled from it,....

If ya got petcocks., take 'em Out,....
Drain Plugs leave the bigger hole,....
Always, Always, poke, 'n prod the holes with a screw or nail to knock the crud outa the way, to be Sure it's drained,...

As noted above, Air just Don't Freeze,....
Water, antifreeze or not, does freeze,..... ;)
 
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Condor1970

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Jun 9, 2014
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195
Got it. Thanks.

I was wondering why all these guys use anti-freeze. I just can't see why.
 

bruceb58

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Mar 5, 2006
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I was wondering why all these guys use anti-freeze. I just can't see why.
There are more people with frozen cracked blocks using anti freeze than any other method when you read the posts in the spring.
 

Bt Doctur

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Aug 29, 2004
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the cast iron dosent dry out and start to shed scale ,either way works, filled or drained.
 

JimS123

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Jul 27, 2007
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Got it. Thanks.

I was wondering why all these guys use anti-freeze. I just can't see why.

If you ever saw a cracked block, then you would see why.

Just follow the directions in your owner's manual. If you don't have one you better get one, they are cheap and easy to come by.

You can't get all the water out in the older models. Naturally, you have to drain first.....duhh. Nobody ever froze a block by putting in anti-freeze if they followed the book first.
 

Bondo

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If you ever saw a cracked block, then you would see why.

Just follow the directions in your owner's manual. If you don't have one you better get one, they are cheap and easy to come by.

You can't get all the water out in the older models. Naturally, you have to drain first.....duhh. Nobody ever froze a block by putting in anti-freeze if they followed the book first.

Ayuh,.... Bull,.... Older motors are Easier than the crap hoses, 'n drain "Systems" used on the newer motors,.....

By pullin' the drains, 'n hoses I've stated here, Over, 'n over, there's NO chance in 'ell of a frozen cracked block,....

Antifreeze is a Waste of money, 'n time,....
 

JimS123

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My owner's manual says drain and then fill with AF. When there is no consensus on a subject I always defer to the manufacturer's recommendations.
 

HT32BSX115

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If you're not really sure that you got all the water, after you poke and prod with a "poke & prodder" take your wet-or-dry shop vac and put a piece of rubber hose on it, and place the business end on each of the "holes" you expose. Let the shop vac suck out any residual water.

It DOES get cold enough here in the NW to crack ANY cast iron block. But if there's no water left in the block, there's nothing to freeze!


Cheers,

Rick
 

Maclin

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May 27, 2007
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In my manual there is a section on Cold Weather Precautions that mentions only draining. In another section called Inhibiting for Long Term Storage it has flushing and draining and anti-freeeze steps along with oil change to special oil with inhibitors and removing and storing the impeller in climate controlled environment.

I just drain for the winter and change oil and filters in the spring.
 

tinkerguy70

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Oct 12, 2012
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My first year of owning a boat I used the anti-freeze method. It's messy and troublesome. After hearing all the old timers here on the forum I stopped using it and just drained as instructed above. After I have drained everything for lay-up, I hook up and pull the boat around the block, just to give her a good shakin'.
Needless to say, I'll just be using the drain only method from now on.
 

jerryjerry05

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May 7, 2008
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One reason that they add liquids is the block/manifold and riser will rust faster if left without liquids.
The air will allow it to rust faster.
IF???? You have drained it the way it should be done?????? Then you don't have to worry about adding liquids.
Making sure you get the stuff built up in the corners, a piece of wire through the drain plugs.
Loosen the drive and allow the water to drain from the hoses.
 

HT32BSX115

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One reason that they add liquids is the block/manifold and riser will rust faster if left without liquids.
The air will allow it to rust faster.
My last marine engine (1966 150 Mercruiser) did not get anti-freeze in it's entire life before I sold it in 2005.....(39 years) It was still running pretty good, but was well on the way to being WORN OUT instead of rusting out.

I would venture to guess that any fresh water engine will wear out LONG before you rust out the block due to NOT filling it with AF each year.

It might be a slight factor with a salt water engine, .................but, I'll defer to my salt-water friends on that one:D
 

Bondo

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My first year of owning a boat I used the anti-freeze method. It's messy and troublesome. After hearing all the old timers here on the forum I stopped using it and just drained as instructed above. After I have drained everything for lay-up, I hook up and pull the boat around the block, just to give her a good shakin'.
Needless to say, I'll just be using the drain only method from now on.

Ayuh,.... The Key to the dry storage is pokin', 'n prodin' the crud outa the drain holes,....
 
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