150 PD vw engine problem snaped fuel piston

[tonbug08]

Hello vw 150 pd and having a running issue. The car seems really noisy seem to get worse after oil change was the right oil came from the dealer. I have changed the injector loom, recent service about 8000 miles it had new Hydraulic tappets, cam shaft bearing and belt.




http://www.youtube.com/watch?v=rEM7jbAezQ4

After i had a better look at the car took the rocker cover of and after bit of looking noticed that second injector in from drive side was sitting on the side at a angle from the rest.. after taking apart bit more to get the to the injector i found that the fuel piston had snapped into two pieces inside the spring, there a link to some photos any ideas what would have caused this and how the engine was running for about 3000 mile like this with no misfire on shudder only on tickover and sounding louder??????