So this is a rookie shade tree wrench cya question. Can a loose pcv valve cause any damage? I noticed on the weekend that my pcv valve was loose enough to pop out without resistance. The rubber grommit had melted/disintegrated and both hoses were split at the cylinder head end. I replaced the gromitt and pcv valve with oem (it was an aftermarket) and backordered the hoses. There was some oil staining on the head around the grommit and the hoses are not air tight right now, but I hope no harm done?