Hi Simon

I had an Astra that had an intermittent rattle from the cams, I found that both vvt actuators had small carbon deposits on their gauze filters. According to Vauhall (I'm led to beleive) you discard the filters, clean out the actuator bores and reassemble without any filters. Thats what I did and cured the problem instantly. The deposits were not really hard so I assume the actuator can break them if they enter it. The astra is still quiet 6 months on.

Mark