Valve marks in piston

[AndreasF]

I'm trying to figure out the root cause of why i have marks in my cyl 2 piston. Clearly the intake valve have met the piston.

























































I bought the car a year ago. It has been sitting in a barn for 20 years. It has been driven less than 10 km by me due to different reasons. There was a valve "tick" on one cylinder when i bought it. Thougt it needed vave adjustment. I changed timing belt + tensioner and adjusted the valve clearance. Camshaft/crankshaft alignment was correct both before and after the belt was replaced. Inspected Camshaft and rockers, Couldn't find anything abnormal.
Due to a oil leak from the head gasket i removed the cylinder head and found this.
I have turned the crankshaft back with one finger on the piston, can't feel any play there. I have also turned the camshaft, the valve closes as it should.

Someone got any ideas?

[moatilliatta]

OVERR3V, broken timing belt, or cam timing off. Chance someone could have had the valve adjustment way out of wack. Maybe got lucky on a dropped valve. Id check the rocker shaft holes for cracks.

[digger]

that's the exhaust valve. Valve could be sticking in the guide to.

given you've done only a few km may be damage from a while ago