Oil in coolant expansion tank

[blacksheep-1]

Look over my post on 07 to 08 coolant upgrade and see if there's anything that you could use there. A LOT of the new mustangs are having the same issue, egg shaping or cracking in #8. So there might be a solution already in the works. It's funny, we ran some of these engines over 270+ in race traffic with no issues.

 

[ArizonaBOSS]

Ugh, terrible to see this. Glad you found the root cause; sorry to hear and understand the repairs necessary.

 

[misterpeanut]

I can't imagine a coolant change has anything to do with this situation. The plastic tab was breaking the seal on the intake runner, leaning out #8. It's unfortunate the knock sensor didn't pick it up, but it's also fortunate it didn't break the piston and cause a cascade of issues. Must have been just lean enough.

What did the number 8 combustion chamber look like? It had to be lighter color.

 

[67GTA]

What did the number 8 combustion chamber look like? It had to be lighter color.

Definitely had a different color, but also attributed to the steam from the cracked sleeve. The piston was nice and clean on the portion nearest the crack.

 

[misterpeanut]

I'll bet! Whenever I get the "my head gasket is leaking why" and I get the gaskets back to inspect them you can always tell an overheated situation because the material of the gasket changes color.