DimanC

hiThank you for yout opinion. I shall check all things - injectors, air leaks in intake gasket (current manifold has two gaskets...), ignition. But I'm 95% sure, that valve itself IS NOT melted. Melted are those deposits (or how do you call them), on valve face. If you take a look at my previous head - it looked exactly the same, and after cleaning that black sh1t from valves, they don't seem to be melted, you can clearly (despite to blurry picture) see all symbols on it: but whatever - I agree, that possible reason of broken valve is too big hot in cylinder.

Hi Haven't read a whole topic yet, but I just want to say that I have also similar problem. The same exhaust valve, gone twice. Subaru Impreza GF6, 1994, 1.8 [ EJ18, SOHC, naturally aspirated ] AWD, European spec. I bought car with ~205'000km, and after some 4 months driving exhaust valve was gone. I changed whole head (from bit newer engine, it was said to be 1.8 USDM), and it run ok for some 14 months, around 15'000km. And then again - the same cylinder (#4), the same valve was gone. What's the reason for those deposits on valve face? both heads: newest below, oldest above. Removed pistons as well, because I thought that cause is oil that gets in cylinder. All seems fine: As next I'm going to check ignition cables, spark clubs must be ok, since they were changed short after first engine head was gone. For a pity I don't have equipment to check injectors, probably that's the fault.