Have been getting head that the valve guides are droping out down into the exhaust port last one was a 07 outback had 4 droped ex valve guides also had a 03 forester motor and a 01 outback motor all droped guides. When the drop the valve hitts them and it damages the end of guide and valve seal falls off I'm not shure if is from overheating or bad casting seems to only happen on #2#4 anyway if doing any head work CHECK HEIGHT OF EX VALVE GUIDES before doing any work on heads I also think this is why so many unexplaned misfire codes. Also a'm looking for valve guides that are machined with a snapring on them to pervent thiss from happening.

sounds like a good idea on the snap rings - if they will stay put.

 

Um, I have an 06 WRX, any idea how common my engine might have that problem? Did these cars seem well-maintained?

ferreli has guides that are 1 thow biger is the best i found yet i think the exhaust over heats the heads and the guides fall down seems to be more of a problem on late model sohc but have seen it on 2.2 and 2.5d but non on wrx yet. I think some kind of heat sink between the head and exhuast whould help. some kind of heat resistat material keep the heat off the heads. To find thiss problem without pulling heads you could look up the exhuast port and see if guides are were they should be. This engine came from wreakers so no idea on matanace but was under 140000kms on it and oil was clean good thing i dident just throw it in there good thing valve were bent or i wouldhave installed a droped guide engine was just lucky i foud it