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I lost compression in cylinders 4 and 5 of my s4 at the end of the winter. I finally got around to taking off the head and this is what I found:
New passageway between cylinder 4 and 5
Reminds me of something that's been flame cut
Cylinder 5 is very clean.
Rich at the front and lean at the back?
Jetting from coolant leaking into the cylinder (clean spot)
An older gentleman at work told me he's seen this before when an engine is running too lean; the head slowly melts away until there is a passageway between the two cylinder. He's seen it on cast iron headers! I still don't know if that's the culprit, but that was my first thought too. Has anybody else seen something like this before? Is this a common problem? I took a quick look through the forum but I didn't see any posts on heads melting. Anybody have any other ideas? I'd love to hear your feedback. Thanks.
I meant to add a question mark to my coolant jetting comment. I don't know if that's what those clean spots represent but that's what it looks like to me.
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Aan melted head
