I recently found a small leak around the rad cap area and thought it was my rad cap that was starting to break down with age since, it's been on the car for the duration that I have had it (6+yrs) and I don't know when it was last changed so, I have to assume it's the original one that came with the car.
Anyway, I bought a new one from my local dealer and while some 200+ miles away from home, it failed on me. Not during the trip but, overnight in the hotel car park. Luckily, I had the old rad cap with me and 5ltrs of coolant & a funnel so, was OK.
Here are some pic's, is this the normal part that fails on the cap ?