I have a 1986 300E w/133k. I recently had a head-gasket done, but I had not yet discovered your great forum, and thus had not yet leaned of the M103's valve problems. I'm now wondering if I should have also done the valves. I burn less than 1q/3000mi.
So what % of M103 valves fail by 150K? Any ideas? Do many make it to 200k before the head comes off? Just curious.