We are back at Estonia! Drove the bus last week 4 days, total about 3800km. All 3600 of those with "broken" engine. Today i got some time to tear it down to see what happened
So after i got the muffler off things looked bad...
i dug on and finally found the reason. again the cylinder #4
so... i took it all apart and... now just have to order some seals and parts and put it back together