Corrosion in Block

[ralphy670]

I have owned my boat from new since 2007. The first 4 years, I left RV antifreeze in the block and manifolds all winter. Although paranoid at times through these years I have never had an issue. The last 3 years I have been flushing the block with antifreeze and draining both block and manifolds and leaving it dry through the winter. I was not as paranoid and again never had a problem.
So this leads to my question. I live in Canada (very cold here) and the boat is used in freshwater only. How much corrosion will this process cause inside the block and manifolds? I have noticed some minor rusty water in the spring after first startup and this fall I have found some crud in the block plugs. I cant really tell what it is though, could be sand or something.

Any information is appreciated as I am curious if anyone has had a major block issue due to corrosion.

 

[HT32BSX115]

Howdy. Many people have fresh water mannifolds that are 20 years old. My last boat had a 150 Mercruiser (66 model) that was original that i sold in 2005. You don't have a lot to worry about. Regards Rick

 

[DaveG55]

My boat is a '94, fresh water all its life. I had to replace exhaust manifolds this past spring. They cracked from the combination of being less than diligent with winterizing and a much colder winter than usual. My fault, no excuses, lesson learned!
Anyway, the water passages, both in the manifold and what I could see in the block, were surprisingly free of substantial corosion. I believe that they would have lasted many more years had my inattention not intervened.

 

[Starcraft5834]

Corosion happens...no matter what..dry storage is recommended by Merc... thats what my manual says..stressed out worry warts use antifreeze..which by the way does freeze..your in O' Canada? You can bet the farm it will turn to slush at least....air dont freeze..even in Canada.. remove what does freeze.. water..in any form...moisture still in there only crystalizes and wont hurt a thing...

 

[Scott Danforth]

my boat is a 1988. fresh water except last two years. did nothing in the fresh water other than drain.

manifolds were great last time I had them off, however down in the salt, will be replacing soon.

long story short. they last 20-30 years in fresh water, and only then are usually murdered.

 

[DaveG55]

Corosion happens...no matter what..dry storage is recommended by Merc... thats what my manual says..stressed out worry warts use antifreeze..which by the way does freeze..your in O' Canada? You can bet the farm it will turn to slush at least....air dont freeze..even in Canada.. remove what does freeze.. water..in any form...moisture still in there only crystalizes and wont hurt a thing...

Two points:
First, my manual clearly says to drain the block then fill with antifreeze.
Second, as long as the proportion of propylene glycol is high enough it doesn't matter if it does freeze because it doesnt expand. The problem comes in when cheap pink stuff is used because it has a lower percentage of propylene glycol and a higher percentage of water which really lowers the burst point. Burst poing is far more important than the freeze point. If you get the stuff with higher prrcentage of propylene glycol you can push the burst point to -100 or so.

 

[thumpar]

Two points:
First, my manual clearly says to drain the block then fill with antifreeze.
Second, as long as the proportion of propylene glycol is high enough it doesn't matter if it does freeze because it doesnt expand. The problem comes in when cheap pink stuff is used because it has a lower percentage of propylene glycol and a higher percentage of water which really lowers the burst point. Burst poing is far more important than the freeze point. If you get the stuff with higher prrcentage of propylene glycol you can push the burst point to -100 or so.

The manuals that I have read either don't mention it or instruct it as added but not a must. Antifreeze will freeze before air will. People worry about corrosion but run there boats all summer long with no protection. The short stay over winter will not save anything.

 

[DaveG55]

Of course antifreeze will freeze before air but so what? Propylene glycol does freeze but DOES NOT expand. It's the expansion that breaks things. Just get antifreeze with a high enough percentage of propylene glycol so the burst point is lower than your winters get cold.
Also, go on Mercruisers website and look up winterizing, it says to use antifreeze.
Not trying to convince anyone to winterize one way or another but lets at least put the truth, out there.

 

[Starcraft5834]

The manuals that I have read either don't mention it or instruct it as added but not a must. Antifreeze will freeze before air will. People worry about corrosion but run there boats all summer long with no protection. The short stay over winter will not save anything.

:cheer2: my gf cheering on................. and agreeing with Thumpar....

Dave. put in antifreeze if you think you need to do that.....have at it and enjoy..............its your boat.....

 

[Bondo]

I have owned my boat from new since 2007. The first 4 years, I left RV antifreeze in the block and manifolds all winter. Although paranoid at times through these years I have never had an issue. The last 3 years I have been flushing the block with antifreeze and draining both block and manifolds and leaving it dry through the winter. I was not as paranoid and again never had a problem.
So this leads to my question. I live in Canada (very cold here) and the boat is used in freshwater only. How much corrosion will this process cause inside the block and manifolds? I have noticed some minor rusty water in the spring after first startup and this fall I have found some crud in the block plugs. I cant really tell what it is though, could be sand or something.

Any information is appreciated as I am curious if anyone has had a major block issue due to corrosion.

Ayuh,..... Yer no doubt seein' sand, 'n debris from the raw water coolin',....

That's the Why, of Us tellin' folks to poke, 'n prod the drain holes, to be Sure it's drained,....
Just pullin' the drain plugs, Ain't good enough, because of the crud that collects at the low points of the system, from the raw water,....

I've got 40 year old blocks, drained each year, with no more corrosion than a brand new motor,....