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View Full Version : What's the BEST way to min internal corrosion?



flying tomato
05-13-2010, 01:52 PM
Like most of you, I have spent some $ on my engine and want it to last a while. What is the best way to minimize internal corrosion of the block and exhaust manifolds.
I have a bbc GM based Marine shortblock and aluminum heads and exhaust.
Of course, I always flush with fresh water after use.

Would draining help or hurt? What about zincs on the block and manifolds?

Thanks in advance,
Flying Tomato

zelatore
05-13-2010, 02:09 PM
Well, the BEST way would be a fresh water cooling system. There are aftermarket systems that can be added for a reasonable cost, but on some Donzis it can make a tight engine room even tighter.

As for zincs, I don't see a lot of value on a system like this. Zincs protect against electrolysis, but as long as you're draining the water when not in use, electrolysis shouldn't be an issue.

And of course, as you mentioned, flushing with fresh water is a major step in keeping everything happy!

mrfixxall
05-13-2010, 02:09 PM
Like most of you, I have spent some $ on my engine and want it to last a while. What is the best way to minimize internal corrosion of the block and exhaust manifolds.
I have a bbc GM based Marine shortblock and aluminum heads and exhaust.
Of course, I always flush with fresh water after use.

Would draining help or hurt? What about zincs on the block and manifolds?

Thanks in advance,
Flying Tomato


internally,the best way would be is to install a closed cooling system..

second,use salt away after every use,just draining it would make it rot faster..

externally,spray everything with ppg dp 40 epoxy primer,then spray over it with imron

Sweet Cheekz
05-13-2010, 03:00 PM
Besides flushing with salt away I always use Boeshield T9 to spray down all electrical connections

Parnell

gcarter
05-13-2010, 04:16 PM
I'm a firm believer in closed cooling.
I wouldn't have a valuable boat w/o one.
Look at any marine diesel used in recreational
boats are all closed cooled. Two reasons;
1) Protection of investment.
2) They run better w/tighter temperature controls.

Here's some thoughts;

http://www.donzi.net/forums/showthread.php?t=50476&page=25

fogducker III
05-13-2010, 04:19 PM
In aluminium intakes there is no harm what-so-ever in placing "pencil zincs" in the water jacket, salt away, as mentioned is a must and obviously flushing with fresh after running.

I have proven to myself that pencil zincs work.......:wink:

DonziJon
05-13-2010, 07:16 PM
Pencil zincs are a good idea. Problem is with the Aluminum. Zinc is very close to Aluminum on the Anodic Table.... therefore much less effective and of marginal protection. :lookaroun:

gcarter
05-13-2010, 07:21 PM
Pencil zincs are a good idea. Problem is with the Aluminum. Zinc is very close to Aluminum on the Anodic Table.... therefore less effective and marginal protection. :lookaroun:

John's right.
Best way is to not let any raw water in contact w/it.

fogducker III
05-13-2010, 07:53 PM
John's right.
Best way is to not let any raw water in contact w/it.

But if there is any "raw" water a zinc is better then nothing, and in salt water they work well with aluminium intakes as well as in un-used water ports on the block........:wink:

handfulz28
05-13-2010, 08:06 PM
They make aluminum "zincs"...aka anodes. Not sure if there's an aluminum pencil anode.

But closed cooling is only way to protect the aluminum with long term confidence. You can install the heat exchanger on the side somewhere; there are pics of different installations. If gcarter will share, he's got some cool ideas. :D

gcarter
05-13-2010, 09:04 PM
The TR is getting a remote mounted HE from Monitor Products and the mounting instructions are below.
Anyway, it will be mounted under the rear seat and on the stringers and completely clear of the engine.
My main differences w/the instructions are, I'll have a crank driven raw water pump and a 12V remote circ pump mounted just above or below the HE.

Cuda
05-17-2010, 08:08 AM
My 82 22C had raw water cooling, as did my 86 Minx, and my 86 Formula. None of them showed any adverse reaction to salt water, and the Formula was run in 99% salt water. I just flushed religiously. I put some dish soap in the hose before I flushed, so when it quit bubbling, I knew it was completely flushed. These are boat engines, not Tiffany Crystal.

I put closed cooling on a 20 foot Formula I had to protect the aluminum intake.
I spent $600 and a chitload of work to save a $150 intake. In retrospect, I should have just junked the intake every few years, it would have been a lot less problem, not to mention once you get the closed cooling in the boat, it leaves very little room to get in to work on anything. I'd never put closed cooling on a boat that didn't come with it. It's not worth the trouble. We will both be dead before it rusts through cast iron.

VetteLT193
05-17-2010, 09:16 AM
salt away.

gcarter
05-17-2010, 10:15 AM
My 82 22C had raw water cooling, as did my 86 Minx, and my 86 Formula. None of them showed any adverse reaction to salt water, and the Formula was run in 99% salt water. I just flushed religiously. I put some dish soap in the hose before I flushed, so when it quit bubbling, I knew it was completely flushed. These are boat engines, not Tiffany Crystal.

I put closed cooling on a 20 foot Formula I had to protect the aluminum intake.
I spent $600 and a chitload of work to save a $150 intake. In retrospect, I should have just junked the intake every few years, it would have been a lot less problem, not to mention once you get the closed cooling in the boat, it leaves very little room to get in to work on anything. I'd never put closed cooling on a boat that didn't come with it. It's not worth the trouble. We will both be dead before it rusts through cast iron.

Joe, did you notice he has aluminum heads and exhaust?

JimG
05-17-2010, 12:01 PM
I've run my Donzi in salt for years. I just flush within twenty minutes of getting her out of the water. I've never had an issue. My manifolds and intake are aluminum. I like the simplicity of raw water.

VetteLT193
05-17-2010, 12:08 PM
I've run my Donzi in salt for years. I just flush within twenty minutes of getting her out of the water. I've never had an issue. My manifolds and intake are aluminum. I like the simplicity of raw water.

+1

Our boats can't really be compared to big inboards because they don't sit in the water. Flush them with salt away and keep the simplicity. With CC you just move any future corrosion to the heat exchanger and I have had more issues with heat exchangers than hard engine parts.

Also... outboards are mostly aluminum. as are the outdrives on our boats.

Cuda
05-17-2010, 12:29 PM
I've run my Donzi in salt for years. I just flush within twenty minutes of getting her out of the water. I've never had an issue. My manifolds and intake are aluminum. I like the simplicity of raw water.
Jim, I agree completly. I ran most of my boats in salt, and never had an issue with internak corrosion. It's a non-issue that some people want to make more of it than it's worth.

gcarter
05-17-2010, 01:09 PM
My boats will have closed cooling.
I think the investment is worth it.
Others don't think it is.
You wouldn't buy a newCorvette and
not run anti freeze in it, would you?

Cuda
05-17-2010, 06:30 PM
My boats will have closed cooling.
I think the investment is worth it.
Others don't think it is.
You wouldn't buy a newCorvette and
not run anti freeze in it, would you?
I imagine a new Corvette would come with antifreeze. If I had to install an entirely different system to run antifreeze, you can bet I wouldn't.

CC on a boat is way overated.

BUIZILLA
05-17-2010, 06:43 PM
Joe, if you went to your sink for a drink of water, and you had a salt faucet on one side, and a fresh faucet on the other, what would you PREFER to drink? :wink:

and why?

DonziJon
05-17-2010, 07:15 PM
I imagine a new Corvette would come with antifreeze. If I had to install an entirely different system to run antifreeze, you can bet I wouldn't.
CC on a boat is way overrated.

Joe: I agree with you completely. These Classics are Trailered which to me makes Closed Cooling an almost non issue. However: If the boat stays in the water..salt water, then Closed Cooling is a GOOD idea. I had it on my 32' sailboat which stayed in salt water six months a year.

On the other hand: Closed cooling allows you to run the motor at the most efficient temperature all the time..say around 190 degrees. AND..because the system is Closed ..and Pressurized..and full of antifreeze...the temperature can run as high as 230+ degrees without BOILING..thereby allowing cooling at much higher temperatures.

Look at it this way; Boiling water is full of bubbles. Bubbles don't cool worth a DAM. Just sayin..

gcarter
05-17-2010, 08:24 PM
I imagine a new Corvette would come with antifreeze. If I had to install an entirely different system to run antifreeze, you can bet I wouldn't.

CC on a boat is way overated.

Well the owner of the new Corvette could make the decision to drain out the antifreeze and put in tap water...........
After all, we're talking about decisions.....closed cooling to protect an aluminum engine, or raw water cooling, which WILL have an impact on it.
The ONLY performance engines I know of that run tap water are NASCAR engines. But they only run a few hours and then are rebuilt.

JimG
05-17-2010, 08:43 PM
No tap water in my Donzi... nothing but salt for me!:bonk:

Seriously, I think we have to agree to disagree on this.

If I bought new Corvette, I'd leave the anti-freeze right where it is. Given the choice, I'd drink fresh water. My Yanmars are fresh-water cooled. If I bought a new engine, I would expect Fresh water cooling. It's a good thing.

But for my 40 year old Donzi, I haven't felt the need to change it. Maybe in another 40?:wink:

mphatc
05-17-2010, 09:04 PM
One approach no one mentioned . .
coatings

My intake manifold, Air Gap, I had it ceramic coated when new . . inside and out . . real easy to clean, still looks new 6 years later .. .when I installed the new AFR heads on the 302, they went to DART Coatings , coated internally and externally . . . I will run the boat in salt and fresh water, rinse only after salt use.
Dart assured me that the coatings will have zero effect on performance.

For the Magnum which will sit in the water for extended periods, I'll do the same, but the exhaust manifolds will be DART coated internally, and the outside will be painted.


on a side note . .
Never powdercoat aluminum or any engine pieces!
A. It insulates and effects operating temps
B. ANY surface or exposed edge will lead to corrosion under the caoting that you can't see. BTDT, NEVER again!

Mario L.

gcarter
05-17-2010, 09:05 PM
No tap water in my Donzi... nothing but salt for me!:bonk:

Seriously, I think we have to agree to disagree on this.

If I bought new Corvette, I'd leave the anti-freeze right where it is. Given the choice, I'd drink fresh water. My Yanmars are fresh-water cooled. If I bought a new engine, I would expect Fresh water cooling. It's a good thing.

But for my 40 year old Donzi, I haven't felt the need to change it. Maybe in another 40?:wink:

Jim, we don't disagree. I wouldn't change anything either.
But the original question was pretty specific, don't you think?

JimG
05-17-2010, 09:56 PM
George, Lee asked about draining and zincs. Never mentioned FWC.

Cuda
05-17-2010, 10:00 PM
Joe, if you went to your sink for a drink of water, and you had a salt faucet on one side, and a fresh faucet on the other, what would you PREFER to drink? :wink:

and why?
I don't drink antifreeze either. :)
I ain't drinking the kool aid with closed cooling either. I can see on EFI engines.

Cuda
05-17-2010, 10:04 PM
Well the owner of the new Corvette could make the decision to drain out the antifreeze and put in tap water...........
After all, we're talking about decisions.....closed cooling to protect an aluminum engine, or raw water cooling, which WILL have an impact on it.
The ONLY performance engines I know of that run tap water are NASCAR engines. But they only run a few hours and then are rebuilt.
The owner could decide to be zapped by death rays from outerspace, but I just don't think so.

How many years were marine engines made without closed cooling? I guarantee there are more marine engines running without cc than with.

Cuda
05-17-2010, 10:06 PM
One approach no one mentioned . .
coatings
My intake manifold, Air Gap, I had it ceramic coated when new . . inside and out . . real easy to clean, still looks new 6 years later .. .when I installed the new AFR heads on the 302, they went to DART Coatings , coated internally and externally . . . I will run the boat in salt and fresh water, rinse only after salt use.
Dart assured me that the coatings will have zero effect on performance.
For the Magnum which will sit in the water for extended periods, I'll do the same, but the exhaust manifolds will be DART coated internally, and the outside will be painted.
on a side note . .
Never powdercoat aluminum or any engine pieces!
A. It insulates and effects operating temps
B. ANY surface or exposed edge will lead to corrosion under the caoting that you can't see. BTDT, NEVER again!
Mario L.
I've heard of people filling the intake with Rustoleum, then pouring it out and letting the intake dry.

Cuda
05-17-2010, 10:09 PM
Jim, we don't disagree. I wouldn't change anything either.
But the original question was pretty specific, don't you think?
George, who are you trying to kid? You'd change absolutely everything about it. :)

zelatore
05-18-2010, 12:46 PM
The ONLY performance engines I know of that run tap water are NASCAR engines. But they only run a few hours and then are rebuilt.

Er, not really relevant, but I think you'll find that almost all road racing motors are NOT using antifreeze in the cooling system. It's actually banned by many sanctioning bodies as it's very slippery in the event of a spill. The cheap guys will be running straight water, while the guys with a bit more budget will run water with an additive like 'water wetter' from RedLine.

On another automotive-but-vaguely-related-to-boats note, A lot of older Italian aluminum engines (Alfa, Fiat, Lancia, Ferrari...) used to use a magnesium plug in the cooling jackets to help prevent corrosion of the head due to dissimilar metals. Basically the same thing we use zincs for on the boats

Cuda
05-18-2010, 01:16 PM
I was driving a Toyota truck that started overheating just as I got on the Howard Franklin Bridge. I didn't have any choice but to let it overheat as I crossed the bridge. Once I crossed it, I got muddy water out of a mud puddle to put in the radiator. It wouldn't be my first choice.
When do you play a crooked game?
When it's the only game in town.

gcarter
05-18-2010, 01:48 PM
Er, not really relevant, but I think you'll find that almost all road racing motors are NOT using antifreeze in the cooling system. It's actually banned by many sanctioning bodies as it's very slippery in the event of a spill. The cheap guys will be running straight water, while the guys with a bit more budget will run water with an additive like 'water wetter' from RedLine.

On another automotive-but-vaguely-related-to-boats note, A lot of older Italian aluminum engines (Alfa, Fiat, Lancia, Ferrari...) used to use a magnesium plug in the cooling jackets to help prevent corrosion of the head due to dissimilar metals. Basically the same thing we use zincs for on the boats
There you go braggin' about your road racin' again......:wink:
Yep, antifreeze is some slippery stuff.

CHACHI
05-18-2010, 02:11 PM
Magnesium is the proper metal for an anode in fresh water.

Ken

VetteLT193
05-18-2010, 02:56 PM
http://www.mercuryracing.com/_media/images/sterndrives/hp1200sci/hp1200sci_med.png



-High-velocity cooling system uses a combination of a circulating pump and sea pump to keep the engine at an optimal operating temperature and peak performance.

-CNC ported, race-prepared aluminum cylinder heads

zelatore
05-18-2010, 04:29 PM
There you go braggin' about your road racin' again......:wink:
Yep, antifreeze is some slippery stuff.

These days, it's not bragging, it's reminiscing.:boggled:

gcarter
05-18-2010, 04:36 PM
Don, the last time Elaine and I went to 'Vegas, we went out to Death Valley and passed that absolutely wonder facility that's located just east of Pahrump.
I never knew it existed until then.
Later, I read about it in R&T, I think.
Pretty impressive.
I suppose it's not a place to go in the summer, unless you're testing prototype cars or something.

flying tomato
05-18-2010, 04:40 PM
WOW!!! That was kinda like lighting a bottle rocket with a broken stick!Thanks to all for the infor and opinions. I'm going to keep doing what I have been doing forever--flush with fresh water every time.flying tomato--out!