Help with Aluminum Corrosion | Auto Repair Shop Dispute

[tirpitz56]

I don't know if this is the place to post but I was wondering if there is anyone out there that is experienced when it comes to aluminum corrosion.
I am about to take an Auto Repair shop to court because I gave them an engine with 5,000 miles on it to swap into my car and when I received my car back there was an engine in it that had nasty, thick orange corrosion all over and it wasn't corroded equally either. It looks like it was piced together. They only had it for 2 months but they said this is how quickly engines corrode.
The pic on the far left and far right are the before pics with the nice clean head circled and the one in the center is after I got it back.
Thanks for any help in advance.

 

[berkeman]

I'm going to move this to the ME forum, where hopefully FredGarvin and Astronuc and others can offer opinions on Al corrosion.

 

[Astronuc]

As far as I know Al alloys do not corrode with an orange color. My guess is that the orange-brown is iron-based rust on carbon steel components.

Aluminum alloys usually form a protective oxide and that helps prevent corrosion. That protective oxide can be undermined if the aluminum surface is exposed to chlorides.

 

[tirpitz56]

So do you think it would be possible for an engine to corrode like this while sitting inside of a garage for 2 months? I have only seen engines corrode after a couple of years of use outside in the elements like sand, salt and other chemicals on the road.

 

[FredGarvin]

I agree that I have never seen aluminum do this. I wonder if this is really corrosion and not some form of chemical attack. I have had test rig parts made from various alloys of aluminum that have been in storage in uncontrolled environments for years with no problems. The only material I have ever seen corrode that quickly is plain carbon steels.

Do you, by any chance, happen to know what alloy the block is made from?

 

[tirpitz56]

I found this on Aluminum.org.
"die-cast aluminum-alloy block with aluminum-alloy cylinder heads"
http://www.aluminum.org/antemplate.cfm?issuedate=09/01/2003&template=/contentmanagement/contentdisplay.cfm&contentid=7085