I parked my 1983 Mercedes 240D in my driveway and when I went to re start it, it cranks freely with no sign of firing. It is cranking at a slightly higher pitch. I have a feeling it might be the timing chain. How do I check it?
Take vavle cover off and see if cam is turning/lifters moving? If there is no rhythmic laboring sound when cranking but just faster steady drone/pitch then you probably got serious issues including some bent valves.