Engine Coating and Block Protection?

[garp2112]

Does anyone know what coats the engine block?  My engine block's surface is chipped underneath the front end.  It is a little tough to see from the below picture but the coating is definitely chipped to the base material. 

Will the block begin to rust and is there something I can apply to protect it?

[scduc]

I believe that it is just paint, and I also believe that the block is aluminum, so it wont "rust". It may however start to oxidize.

[He Man]

the paint on my engine is peeling off the same way, but in more than 1 spot. im planning on stripping it and repainting it with something more durable.

it wont rust like iron does, but it still "rust" or rather it oxidies into this hazy white finish that is dry to the touch. wont harm the aluminum.

[ducpainter]

the paint on my engine is peeling off the same way, but in more than 1 spot. im planning on stripping it and repainting it with something more durable.

it wont rust like iron does, but it still "rust" or rather it oxidies into this hazy white finish that is dry to the touch. wont harm the aluminum.

Until it's all gone.

The white powder is aluminum oxide.

Rust is iron oxide.

After time they both 'rot' away.

[He Man]

Until it's all gone.

The white powder is aluminum oxide.

Rust is iron oxide.

After time they both 'rot' away.

it'll be a long time before the aluminum rots away unless you spend every waking second rubbing the aluminum oxide away.

[ducpainter]

it'll be a long time before the aluminum rots away unless you spend every waking second rubbing the aluminum oxide away.

True...

but your statement of...

<snip>or rather it oxidies into this hazy white finish that is dry to the touch. wont harm the aluminum.

is pretty inaccurate.

[He Man]

True...

but your statement of...
is pretty inaccurate.

Can you clarify? the oxidation layer should protect the raw aluminum underneath.

[64duc]

I have a 1964 250 single that was sandblasted in 1967 that except for the oxidation looking bad is still sound. it'll last longer than you will.

[ducpainter]

Can you clarify? the oxidation layer should protect the raw aluminum underneath.

If that were the case wouldn't rust protect the metal underneath?

That would mean cars would never perforate from rust which obviously doesn't happen.

I realize that the casting that makes up our crankcases is thick enough to out last us.

My only point is bare aluminum does get harmed from oxidation.

[He Man]

If that were the case wouldn't rust protect the metal underneath?

Rust is the term for Iron oxide or any iron based metal that oxidizes.
Aluminum oxide is not called rust

and if iron rusted teh same way aluminum did, it would protect the base metal. It just so happens it doesnt. Iron rust in huge chunks and gets flakey, and when it lifts it exposes new iron and the process continues till it eats it away.

[ducpainter]

Rust is the term for Iron oxide or any iron based metal that oxidizes.
Aluminum oxide is not called rust

and if iron rusted teh same way aluminum did, it would protect the base metal. It just so happens it doesnt. Iron rust in huge chunks and gets flakey, and when it lifts it exposes new iron and the process continues till it eats it away.

I understand the difference. I can read.

I've been working with metal longer than you've been alive. Maybe longer than your father has been alive.

Just because it isn't called rust doesn't make it good.

Oxidation is bad for all metals.

All oxidation harms metal.

If that wasn't the case the aerospace industry wouldn't have such strict anti-corrosion processes to control corrosion.

How many planes have to crash from corroded aluminum parts before you believe it's an issue?

[scduc]

I'm not sure that the oxidation of Aluminum has the same repercussions (short term) as that of carbon based steel. It does however break down the chemical makeup. Therefore it will affect the long term stability of the alloy. Steel will be affected by the process much sooner than aluminum so in a way you are both correct. I think that by the time that the oxidation's affect the aluminum to the point of failure, the bike will have many other issues. So to say that it's not going to hurt it any, well not in the bikes life time. Than again, if he is still riding it in 40 years, yeah it will be a concern.

[gOoIe B]

Saw this discussion, thought I'd throw in a couple pennies...

I suppose this point has already been made but rust is oxidation.  It is oxidation of iron and other ferrous alloys.  Lots of metals oxidize in different ways based on their chemical properties and the substances they react with.

This also makes it true that the oxidizing rate of cast aluminum is slower than that of say, mild steel, given the same environmental conditions.  The structures created by the formation of aluminum oxide typically do form a dense and nonreactive layer above the aluminum object.  But it is still penetrable by most liquids and gases, and the aluminum object will continue to corrode so long as it is exposed to the environment which initiated the corrosion.  This is typical of the oxidation of most metals, BUT, there is at least 1 exception I can think of right off hand.

And while its not really relevant to monsters, or motorcycles (save for some crush washers and other odd bits), copper is one such metal which is not ultimately destroyed from water oxidation.  This is one reason why it is used in your house's plumbing (in addition to being naturally antimicrobial).  The oxidation layer that forms on the inside of the copper pipes forms quickly, but remains thin because the layer is so dense, it blocks the water from contacting and reacting with the pure copper.

Of course none of this is likely new information for most yous guys, but since when are a couple pennies something new to somebody anyways?

[He Man]

All oxidation harms metal.

If that wasn't the case the aerospace industry wouldn't have such strict anti-corrosion processes to control corrosion.

How many planes have to crash from corroded aluminum parts before you believe it's an issue?

Planes go through extreme temp differences, pressure differences, and any corrosion gets blasted off, exposing new metal until it gets painted. Though true, It has no valid point in my argument which is, If you leave the oxidation layer alone in the case of Aluminum, it will not continue to eat through.

Start washing the layer off every day and neglecting it on something that keeps weight to a minimum  and has huge forces applied to it and you almost have to be the worst gambler in the world to say it wont eventually fall out of the sky.

[ducpainter]

Planes go through extreme temp differences, pressure differences, and any corrosion gets blasted off, exposing new metal until it gets painted. Though true, It has no valid point in my argument which is, If you leave the oxidation layer alone in the case of Aluminum, it will not continue to eat through.

Start washing the layer off every day and neglecting it on something that keeps weight to a minimum  and has huge forces applied to it and you almost have to be the worst gambler in the world to say it wont eventually fall out of the sky.

Are you going to be an ME?

I guess corrosion inside a wing structure gets blasted off all the time. 

You totally miss the point, and I'm bored with trying to convince you that oxidation of aluminum is harmful.

Why are you painting your engine?