the other day while changing my oil i noticed that my coolant resovior looked like a couple drops had leaked outta the cap and when i went to unscrew the top there was alot of pressure built up behind it.... could you give me info as to whats going on here? i'm guessing it's egr related problems maybe?Thanks

 

Or headgaskset related problems.

 

Thats may just be normal. Mine and a buddys burp bottle does it.