This car was an absolute fucking nightmare(1985 Mercedes 500SL, imported from Germany). It started with a leaking radiator that overheated the engine. Which obviously led to blown head gaskets as I was road testing it. So the heads got removed and sent to be milled flat. After re-assembly it was smoking blue. An attempt to replace valve seals showed the guides were loose in the heads. Heads come off again to be repaired. During second re-assembly is when the head bolts wouldn’t tighten. So the whole engine gets removed and sent to the machine shop so they can figure it out. I learned several years later that Mercedes had a huge fixture that made drilling the holes straight and to the proper depth fairly easy so I probably could have done it at the dealership. But it was much easier to let the machine shop worry about it. After re-assembly #3 it finally ran under its own power again but still smoked a tiny bit. We told customer that it was probably stuck rings and that he could pay for a re-ring but it would cost another small fortune( I think all the above was about 5k) or he could take the chance that it was a symptom of overheating and after a few oil changes it might resolve itself. He was actually from far away and this happened randomly near our shop. Blessedly, he decided to take this fucking thing home and far away from me
