WWGRMD? Aluminum head corrosion

What would the hive do with this head? I bought it mostly sight unseen, a couple of pictures and a half ass spec sheet. 

I posted about this in my Z build thread but I haven't been able to get it off my mind. I'm torn between three options: cleaning and neutralizing the corrosion then filling with Loctite Fixmaster 2000 and having it surfaced flat. Or, paying someone to weld new aluminum in to the cavities created by the corrosion. 

The third option is to admit defeat and spend the money on another P90 head (I've sourced one locally, just wanting to avoid even more unnecessary expenditures). 

I'll post more pictures soon

Look how close this is. Makes me nervous.

Also this one

And overall.

I'm really hopeful I can salvage this head without spending a small fortune, it has a nice port job, and is set up the way I want it otherwise.

I have had a Mercedes head repaired by welding and machining it. A good machine shop should be able to make it like new.

For the expense of having it repaired, unless the other head is $1500, I'd start with the other head.

Have it cleaned and checked... and any areas you have concern on bring it to the attention of the shop and have them weld it.

I'm currently having a head welded (OST-090) because it has a flaw on the fire ring of #4

I think I'd toss it unless it's costly. On a possibly related note, I learned the hard way about using deionized water as coolant. I ruined a prepared aluminum head, with it looking as though I'd poured acid into the cooling passages, and that only took about six months, eating right into an intake port. 

I would spend the $300 for a used head.  I doubt you could get it welded and machined for that little

kb58 said:

I think I'd toss it unless it's costly. On a possibly related note, I learned the hard way about using deionized water as coolant. I ruined a prepared aluminum head, with it looking as though I'd poured acid into the cooling passages, and that only took about six months, eating right into an intake port. 

I've never seen before/after comparisons, but it always made me wonder how distilled water actually does.  The lack of solutes makes it non-conductive, but it also makes it highly solvent.  The distilled water will have all kinds of ions in it within  10 minutes of running.  It's just a difference of where the ions come from.  Are they already in the water (tap water) or are they sucking them from anything they can (distilled).  I would think that bimetal corrosion would be far worse in the long run with distilled, but that's just how my chemistry brain thinks.

In reply to Curtis73 (Forum Supporter) :

That has always been my thinking, too. "Loaded" water won't corrode/dissolve metals at the same rate.

I am also no chemical engineer, but my gut feeling is that coolant anticorrosion additives merely take the place in the water of the metals.

Certainly any potential leaks in the system will allow air in, which oxygenates the water and promotes corrosion.

What is kind of funny is that apparently the first few boatloads of watercooled VWs (iron block, aluminum head) to the US had saltwater in the cooling system instead of antifreeze, to avoid some sort of tariff.  This had predictably gruesome results.

It depends on your tap water.  Mine is always full of lime and leaves deposits that clog the passages.

Curtis73 (Forum Supporter) said:

kb58 said:

I think I'd toss it unless it's costly. On a possibly related note, I learned the hard way about using deionized water as coolant. I ruined a prepared aluminum head, with it looking as though I'd poured acid into the cooling passages, and that only took about six months, eating right into an intake port. 

I've never seen before/after comparisons, but it always made me wonder how distilled water actually does.  The lack of solutes makes it non-conductive, but it also makes it highly solvent.  The distilled water will have all kinds of ions in it within  10 minutes of running.  It's just a difference of where the ions come from.  Are they already in the water (tap water) or are they sucking them from anything they can (distilled).  I would think that bimetal corrosion would be far worse in the long run with distilled, but that's just how my chemistry brain thinks.

Note that I wrote deionized water, not distilled. My theory (never researched) is that deionized water really wants its ions back, and gets them from the aluminum. To be fair, I was not mixing in any coolant, because California. I think I did add Water Wetter though.