Thread:

Drain the block every time or not?

When I pulled my motor apart I had a good deal of electrolysis going on with my aluminum heads. It seems like some where I read most of that happens while the boat is sitting on the trailer. Seems the obvious thing would be to drain the block every time...???? Or would the block itself tend to rust faster while sitting dry?? Any thoughts here?

Originally Posted by toddnjuzz

I try to drain my block a few times a season, if not every time, but who is to say that it's saving it from rust or corrosion?...Does it rust more when its full of water? or when its moist inside of the block?? I dont know??
I get sand out of the block when I drain it also, I know that a build up of that will definitely not be good if it clogs up a psg way.

I actually run -6 out of the bottom of my block to keep the sand from ever settling. One out the neck, two out the bottom of the block.

I think moisture would make it rust faster rather than sitting full of water Just a guess?

Originally Posted by LicktySplitJr

I think moisture would make it rust faster rather than sitting full of water Just a guess?

That's what I was thinking..could be wrong though.

Originally Posted by LicktySplitJr

I actually run -6 out of the bottom of my block to keep the sand from ever settling. One out the neck, two out the bottom of the block.

I think moisture would make it rust faster rather than sitting full of water Just a guess?

For galvanic corrosion, no.

Galvanic corrosion is dissimilar metals, in contact, with water contacting both.
This sets up an electrical current flow, not unlike a battery (very weak one).
One metal sacrifices itself.
Humidity will very seldom do it, so much as a drop of water, will.

I have seen it with very few heads, since the heat of the engine having run, dries the heads and the upper half of the block out, at least in jet aplications like mine where the block auto-drains to aprox 1/2 way (the water inlets) every time it is trailered.

I run iron heads, BUT, in 4 years I have negligible corrosion in my Al. intake manifold (was off last winter).

Where's a place to pick up some anodes?

What about closed cooling? Just let the block sit around in anti-freeze-coolant and keep all of the sand and raw water away from your alum heads.

Plus, specific to jets, no chance of blowing an intake or head gasket from too much water pressure. If the pressure valve failed, it would just send a butt load of water pressure through the cooler.

Also the engine will be happier staying at a constant temperature and not having cold water thrown into it when hot.

Originally Posted by cfm

Dart, Canfield, Brodix, AFR offer hard anodizing..........before the fact.

I would drain the block after each use and also consider using an anode in one/both of the intake manifold water ports.

I have a set of anode's...sorta, so far I've only got the drivers side one in. I put the one in the drain hole, the other drain hole has something up with it and I was going to put it in a freeze plug. Do you think the ports on the back of the intake manifold would be a better place? I'd rather not try my freeze plug plan if I can help it. My other thought was why have the anode sit there and get eaten up while the boats on the trailer. I guess according to Smoking the heads are "dry" whether I drain the block or not, I didn't realize that.

Originally Posted by toddnjuzz

I try to drain my block a few times a season, if not every time, but who is to say that it's saving it from rust or corrosion?...Does it rust more when its full of water? or when its moist inside of the block?? I dont know??
I get sand out of the block when I drain it also, I know that a build up of that will definitely not be good if it clogs up a psg way.

Years ago I had a chat about this with a rep from FelPro...I was told their testing showed a "wet empty" block would corrode/rust quicker vs the same component full of water. I only empty mine when I winterize and fill with 50/50 antifreeze.