I had driven my 2006 v50 t5 on the highway for about 50 miles before i noticed this. The black circular cover on the right side of my camshaft was blown off with spot of oil here and there. I checked the oil and I had plenty left. I snapped it back on and the car has been running fine but i'm not sure if this might be an issue in the future.

here is a picture of the part that came off

2001-2004 Volvo S40 Camshaft Seal - Beck Arnley, OE replacement, Front - JCWhitney

 

So this problem just became a little more serious. I found my camshaft plug blown off again today but after a 350 mile drive from Waco to Oklahoma. this time however it was completely destroyed. It was bent in half with a nice gash in it. I can not figure out what could have caused this? it didn't make any noises or act differently. i just check my engine before and after long drives so i can catch stuff like this. i'm looking into an aftermarket replacement that wont have this issue. my only modifications are an IPD rear sway bar and a k&n intake which I cant imagine causing the plug to just blow apart like this.

here's a replacement from IPD
Cam Hole Plug/Cap

 

Maybe a combination of PCV over pressure and a loose cam hole plug? Have you got the turbo cranked up a bit? Maybe a dab of RTV when you install the new cap. Something to look out for on my car too.

 

Hudini you were right. I'm not running more than stock boost but i replaced the whole PCV system and got a new cam plug. took me a full day and a half to figure out what I was doing but I had the new plug and PCV installed then I ran fresh oil and a new filter. I also run some fresh coolant because i pulled a hose that was in the way while removing the old PCV. I red lined it a couple of times and its staying on so I think that was it. the old PCV was choked off with black sludge and build up.

now my question is how do i modify my car to not have this problem in the next 100k miles. is the a breather system out there for the T5 s40/v50's?