drivrswntd

Running a monitor system as well. Have it on my 548 tall deck. Running a half system as I have CMI's. Never had temps above 170 and the system performs great.

http://www.monitorpro.com/products/i...i=14&f=14&c=20

Budman II

iTrader: (1)

TBF, I'm more worried about corrosion and mineral deposits in the aluminum heads and intake than I am worried about the cast iron block rusting. We almost never see rusted out blocks around here, as it is exclusively fresh water. However, the water is pretty hard (high mineral content), and therefore we can get some mineral deposits building up in aluminum water jackets and causing blockages. I have read that aluminum oxidation actually provides a protective layer against further corrosion, so it would seem that draining the block wouldn't hurt in this regard with fresh water.

I think one of the major issues with aluminum heads / cast iron blocks is galvanic corrosion between the dissimilar metals. I'm seriously thinking of looking for some kind of screw in anode that I can install in one of the water ports on the intake manifold to help with this. Also planning to make sure everything is grounded together.

tpabayflyer

I am not a chemist or chemical engineer by any means..... but I would say why not do your own cast iron rust/corrosion test? Got a used mild steel bracket or two or something similar? Drop one in a bucket filled with anti freeze/water and hose the other one down real good and leave it outside...... after a week, which one would you like your cooling passages to look like? Raw, wet, cast iron will rust superfast when exposed to air........ faster in a salty environment for sure..... I always flush my raw water cooled wellcraft engine after each use and use salt away as well. It is a rust and corrosion preventer and remover....... I would say it would be a good idea for you too, but I would never leave my block exposed to ambient air unless it was either full of anti-freeze/corrosion inhibitor or pickled with some kind of petroleum product..... rust never sleeps!

Budman II

iTrader: (1)

TBF, since I'm raw water cooled right now, the proper test would be to take a piece of cast iron and aluminum bolted together, drop one in a bucket of fresh river water for a couple weeks, and dip the other in the water and then let it sit out for a while. However, to be truly representative of what goes on inside a raw water cooled boat motor, the test would probably have to be carried out over a few years. Now if we wanted to make things interesting, take a third bucket and add some stray current to it.

In order to pull this test off, it would mean that my engine build would take even longer, and I would incur the ridicule of OSO!

I would love to hear from some folks who have done it both ways - leave the block full of water all summer, versus draining it down after each use.

mike tkach

iTrader: (3)

i agree with tbf,oxygen in the block speeds the oxidation[rust]in cast iorn and steel.

Budman II

iTrader: (1)

What about aluminum?

tpabayflyer

I would go on the salt away website and check it out.... I know you are not in the salt but I think it would be a good idea to use it anyway..... It foams up and leaves a protective coating all throughout the cooling passages in your engine..... Maybe there is another product to use but I bet your engine will rust/corrode ten times faster if you drain it after each use and let air get to it.... Maybe check with your machine shop and see what they recommended? Notice how fast freshly machined engine parts rust?

I would install a half closed cooling system if you are so concerned about the rust/corrosion issue. It should work fine for many years..... Look at the millions of automotive engines on the road with cast iron blocks and aluminum heads and accessories..... Anti-freeze with corrosion inhibitors built in are surely the way to go. Your engine will warm up quicker and stay at an efficient temp and probably last longer than if it was raw water cooled. I would say spend $6-700 on a good system and your problems are solved forever!

Budman II

iTrader: (1)

It's tempting to install the closed cooling, but honestly I have already dumped way more money into this old boat than I should have, and there's a fair chance that I may swithc back to stock power at some point and drop the 489 into one of my Camaros to play with on the street. I have run aluminum intake manifolds on my engines for many years and seen very little if any corrosion in them. Like I said, I think the larger issue around here would be mineral deposits instead of corrosion, although I'm sure it could happen over time, especially if you have some stray current involved.

Thanks for the info guys - this has been an informative thread.

ezstriper

if you are running in any kind of salt...won't matter will eat the hell out of the aluminum parts quick....you can drain all you want...closed system is the ONLY way to protect them..

Wes Burmark

San Juan Engineering in Bellingham, Washington is another option for closed cooling systems as well as oil and power steering coolers. They do custom work as well as regular kits.