From what I've read, the 1.0 has had coolant loss issues that lead to overheating and engine damage s ranging from head warpage to gasket fails to blown engines.
There has been some issues with coolant tubes and connectors that are becoming brittle and crumble or break due to heat exposure. I have not found any deifinitive explanation of this engines causal problems. But, if an engine loses coolant it will have nearly immediate big problems
Ya i think we are all aware that if an engine losses coolant it can usually have bigger issues due to coolant lose . Lol
Devils advocate mode...
Ah but see coolant loss issues can be monitored and sorted out with diligence by the end user in conjunction with the manufacturer. In fact in the BMW world damn near all of their inline 6’s are prone to coolant leak out the back of cylinder headgasket areas leading to a blown headgasket. Its not a if its a when yet I don’t see people bemoaning the engines as diasasters. Lol
This includes the much beloved M3 engines.
I only bring that up because people on the internet tend to blow things out of proportion. Not saying this stuff might not have happened.... but how bad is it really and how many people have really been affected? Also are there extenuating circustances that have increased probability.
I would hazard to say a bigger issue was the Focus RS head issue which turned out to be a wrong gasket being installed at the factory.