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Message: <blockquote data-quote="daneast" data-source="post: 23423" data-attributes="member: 6666">Here's an update since outback bumped this thread.I pulled the engine and tore it down. I've never seen valves with so much soot / carbon buildup on them. The exhaust valves had 4-5mm (1/4") built up on the back side of them. What broke was an exhaust valve, and the cause was almost certainly a chunk of that carbon broke off and got between the valve and the head, breaking off the edge of the valve.The cause was piston rings allowing oil around to the combustion side. Burning quarts and quarts of oil has bad implications, which is what you see in these pictures, even if you keep it topped off so it doesn't run low.I replaced the exhaust valves (they looked horrible - terribly pitted), lapped the intake valves (they looked good), all new timing stuff (chain, guides, tensioner, cam phasers), new Hastings rings, new connecting rod bearings. And of course all seals, etc.  Keep in mind this engine had less than 80k miles and was meticulously maintained. I rebuilt a 1.6 liter Suzuki Sidekick engine with 200k miles on it that looked far, far better internally and was still running fine, to give a comparison.Fortunately the only actual damage was to the valve - the cylinder and pistons, etc, looked fine.[ATTACH=full]2558[/ATTACH][ATTACH=full]2559[/ATTACH][ATTACH=full]2560[/ATTACH]</blockquote>