Glass media taking chunks out of coolant passages

[MeowBox]

Here's the story, I dropped my head off at a local machine shop to have it surfaced and get the valve seats done.
A couple days later I got a call saying that as they were glass beading the head the coolant passageways started to flake off as the pics should show.

Has anyone seen anything like this, I've heard of it happening but not like this? Do you think the shop did anything wrong?

 

[Tnice17]

I dont think they did anything wrong. The aluminium is obviously soft/corroded in those areas. Cast iron block and aluminium head, dissimilar metals, will do things like that.

if your doing a high HP build, id get a new head. If its a stock rebuild - i would lay the HG on the head and see if those areas will prevent any sealing issues. Getting the head resurfaced would be wise idea to help clean up the surface. Will have to use your best judgment.

 

[supranaut]

Pretty typical from what I've seen. Some of the pits are pretty bad in the combustion chamber...I don't think you will be able to take that much meat off and still be able to use it!

 

[MeowBox]

Thanks guys, I didn't think they did anything wrong so I've already dropped off another head that looks not so corroded. My main concern was that this was going to happen again but, I guess we'll see.

I'll be putting up a build log sometime soon. Cheers!

 

[adampecush]

I'd try source a known good head that hasn't been sitting on a blown motor for the last 5 years. Lots of things can hide on these heads like pitting and cracking in the combustion chamber. if you're going for high power, have the head dye penetrant checked.

 

[supraguy@aol]

I've had that happen to my head. If you use traditional green antifreeze, or straight water, or get combustion gases into the coolant jacket- any of those
can cause pitting.