Hello everyone. My 2012 Subaru Legacy (2.5i, non-turbo, 134,000 miles) got an issue. I am hoping someone can explain what could have caused it, because I am at a complete loss.\n\nA while ago, out of a blue, the engine started idling very rough, lost power, could barely accelerate. I ended up towing it back home. After a bunch of investigation, I realized there is zero compression in one of the cylinders. Not low compression, but 0.\n\nAfter removing the cylinder head assembly, I can see that one of the valves does not close all the way. When I removed it, I saw that the valve guide popped out (see attached image) and is preventing the valve from closing. The cylinder next to it has a similar issue (valve guide popped out), but not far enough to cause this problem. All other valve guides on that side of the engine look good. I did not remove the other head assembly.\n\nI am looking for a replacement left cylinder head assembly. In the meantime, I am wondering if anyone can suggest what could have caused this to happen. This car is my kid transporter, was maintained well, never abused.\n\n[IMG]https://i.imgur.com/Qboov8j.jpg[/IMG] \n\nThank you very much!