Just draining block is not enough

[shaw520]

I saw a video where a guy took white vinegar poured it over salt and in 3-4 mins the salt had dissipated.....(just a random video on YT),... But in the NE fresh water (upper hudson river) we dont have salt,... so Im thinking salt away is NOT the optimum component,..if I were to guess, the flake that comes out of our block is 75% metal scale, 15% sand, and remaining is algae ect. So as Scott mentions above there's probably a better chemical (Oxalic acid) or something better suited.
75-80% of the flake that comes out of our cooling systems will stick to a magnet.

 

[shaw520]

Evapo-rust,.... claimed non-toxic and turns metal flake into liquid ??

https://www.youtube.com/watch?v=MO4lFxl6oE4


Evapo-rust also makes a product caller Therma-cure
https://www.youtube.com/watch?v=wW4LlVJ19MA

Thoughts on filling the block with one of the above products,... let sit 24hrs,.. then start engine ???

 

[Lou C]

Well, I am in the drain and add -100 camp and I can say based on doing it for 15 years in salt water, when I took my engine apart due to blown head gaskets, what I found was the only passages in the block that were clogged, were the smallest ones that you could easily rod out with a drill bit by hand, none of the larger ones were the least bit clogged, and none of the passages in the heads were. There was of course flaking rust in the cooling passages, which is un-avoidable with raw water cooling. The heads had not yet rusted through, but there were cracks on the exhaust seat area and the cooling passages were eroded to the point that the machinist felt that even if they were welded they would not seal properly so we installed re-man heads.
After the top end rebuild I noticed that on the water hose it consistently ran about 10-15 degrees cooler than before, this most likely due to the reman heads with no scale in the cooling passages and all the cooling holes in the block were opened up fully. I thought of a way of flushing the block, every few years, by fabbing up a fitting that would bolt over one of the water pump inlet holes in the block, with a controlled source of water pressure, you could flush out a lot more of what's in the block, than you could ever get out of the block drains being much smaller in diameter. So you'd just need a few new WP gaskets, remove the pump, bolt up your hose adapter and use a valve on the water hose to limit the flow and pressure (don't want high pressure there, just enough to move water through). Just an idea, not sure if its a good one.

Of course all of this silliness could be avoided with standard closed cooling!

 

[Maclin]

Our boats have all been fresh water,...and the scale is plentiful,... maybe not as corrosive as salt water, but plenty of rust scaling no doubt.
The boat next to me at the marina is a 46 Four Winns with twin Volva Penta Pods,...installed on it is a Nuetra-Salt system that automatically injects the solution for 30 seconds on shutdown (just prior)

How does it know ahead of time that you are shutting down?

 

[shaw520]

How does it know ahead of time that you are shutting down?

You hold the injection button down for 30 seconds, then shut engine down

 

[QBhoy]

I just finished winterizing 10 minutes ago a motor that was new 2 years ago. I didn't think the drain holes would show a need to be probed already. I was wrong. One side block drain was nearly plugged solid. Came out easy enough. Like Chris, no way I am adding anti-freeze. I get my motor up to temperature, shutdown and start pulling drains. I end with the water pump hose and then pull the outdrive. Motor then steams for a while. Will have temps in the twenties starting tomorrow night. There ain't nothing there to freeze.

That said, if enough scale is built up to block heads, they are toast whether you add antifreeze or not. No way a quick anti-freeze swap is going to replace all the plain old freezable water stuck behind those blocked passageways.

Rick

My reason for anti freeze Rick...is to stop the very thing you refer to above. Rotting corroding flaking engine internals.

 

[Rick Stephens]

My reason for anti freeze Rick...is to stop the very thing you refer to above. Rotting corroding flaking engine internals.

Good luck with that. Very humbly believe that my dry winter block ain't makin rust. All spring and summer though, it has water in it sitting 24/7. That's what makes scale build up.

 

[Lou C]

Then why does Mercruiser themselves recommend it in all their shop manuals?
Take a look its all there. And I can tell you with 16+ years of raw water cooling the block on my boat has not rusted through and it does drain, after the holes are poked. It has been filled up after draining every year with -100 marine AF or 50/50 mix of Sierra no tox PG antifreeze.

100% salt water use. Iron oxide (rust) is Fe O2. With antifreeze you don’t have room for the O2.....

 

[Rick Stephens]

I think we can agree there are two types of people here - those that do, and those that don't do. Whatever makes you happy.

 

[shaw520]

I'll agree with that,.. But those who dont shouldnt advise others to not,,...or it could result in a very expensive venture for the unknowing.

 

[Rick Stephens]

I'll agree with that,.. But those who dont shouldnt advise others to not,,...or it could result in a very expensive venture for the unknowing.

And a new priesthood is formed.

 

[Scott Danforth]

boating is expensive. its an acronym for a reason.

rust doesnt stop once it starts - boat motors should have heat exchangers and be running AF, however the majority of cheap buyers dont want to pay for it up-front

the typical half-system HX system costs about $600 for the HX, Bracket and hoses, about another $200 for a full system. a raw water cooled motor has about $100 worth of hoses. that $500 delta would cost the average boater another $2-3k or so on the purchase price. most people shop by price, hence the reason most boats do not have a HX

 

[QBhoy]

Totally agree there are two types of thinking on this...but at the risk of being arrogant...one is wrong and one is right. Put simply, if the block is filled with a liquid, it is less susceptible to corrosion than if not...especially over cold, damp and changeable conditions winter storage.
For those who say that they have drained and not filled with antifreeze for 30 years and maybe more...that’s totally fine, but no doubt the crud you clear out every time is a result of corrosion on the internals. Doesn’t make it good practice and I would think rather just perhaps a testament to how hardy these GM engines are. Doesn’t make it a good thing to encourage the corrosion though.

 

[TurtleTamer]

I don't think it makes a bit of difference whether you add AF or not. I'm somewhat new to this. I bought my 38-year-old boat from an old man that had a 2003 engine in it. The boat seemed meticulously maintained. I bought it in March of 2017 while it was still winterized, or rather, I had it demonstrated while still winterized. What the old man had done for winterization was drain, add AF, fill gas tank, add Stabil, and run fogging oil until it quit. Well, that was ALL he did on the boat. He'd never, since 2003, changed the impeller, bellows, rebuilt the carb, changed the cap and rotor, anything but maybe the motor and drive oils. MAYBE he'd changed the impeller at some point but the riser and manifold in the 3.0 were most definitely 2003 vintage.

I do believe the man didn't do a lick of maintenance he didn't think he needed to. I think he added AF each winter and flushed with hose water after each use (salt water boat). My first season with it, I relentlessly flushed it each outing and when winter came I drained and put no AF at all in it. I didn't even drain the water pump hose, just the block and manifold. Come this year, the riser was done, and it took out my valves and I had a warped head, either from one time when it got hot or from water in cylinders. Either way, I had the head off and let me tell you, I couldn't tell that there was really any scale or rust whatsoever. This is on a 15-year-old motor with questionable care and maintenance in salt water, 14 of which with the old man and one with my inexperience.

I lack the experience many in this thread do, but I'd venture to suggest that good flushing after each and every single use is more vital than how you winterize, as long as you winterize in some way, of course. It may even be important in fresh water, though I'd never think that. Maybe tap water from the hose is good for flushing out lake and river water.

For what it's worth, the metal inside the GM 3.0 head and block were in MUCH better shape than the thermostat housing, manifold, water pump and riser. The difference in the factory long block and these parts was night and day!

 

[shaw520]

, but I'd venture to suggest that good flushing after each and every single use is more vital than how you winterize

There are many variables,.,for instance the quote above would suggest that we all take our boats out of the water after each use, my boat stays in the water from mid April thru end of Oct...so flushing is not an option. Ad to that a 7mph constant current and a 0-6 mph tidal exchange two times each day, and my guess is that electrolysis plays a huge role in corrosion. Yes the sacrificial zincs are supposed to absorb that, but they are not nearly enough to handle the load. My previous searay had an onboard electrolysis supressor unit..( Galvanic Isolator),..not really sure how it works,... But i never saw the rust flake in that engine that ive seen in others without the system. Promariner makes a newer version but theyre pricey,.. $400+. But with more proof that they work im considering installing one.

 

[zellerj]

Would taking IR temperature measurements at various points of the block and head give us a clue with respect to how plugged our cooling passages are? I assume with a new engine the block would be fairly uniform in temperature, and as it gets blocked with sand, dirt, rust etc various portions of the block and head would manifest a different temperature.