We just replaced valves in 3&4th cylinder after a broken spark plug. Car was running fine for 1000 km and we have again compression loss in 3rd. Can the piston be dropped down and removed via oil sump?
When you did the compression test did you try poring some oil down the spark plug hole and testing again? If compression is higher after oil is applied it is probably a piston/ring problem, if it stays the same valve issue. If you can borrow a bore scope that may shed some light on issue. What caused the broken plug? Maybe faulty injector causing lean running in that cylinder which could have burnt out new valve too.
Thanks, yes I did the oil trick and more or less same result I.e. 10-10-0-10 so it may be a valve problem again. We probably need to take the head off and see what's wrong. I looked inside, clearly see the piston and nice and shiny cylinderwall
