WE NEED YOUR HELP! There's a problem with our van.

We have a problem with our van and need your help.
We have a 2008 Mercedes Sprinter 313 CDI and every 500miles it starts to smoke huge clouds of white smoke. This continues for about 50miles then it stops. Runs perfectly for the next 500miles then starts again. We have logged the mileage on the last few times this has happened and it's regular as clockwork.
The van had a new EGR valve, new Catalytic Converter, and New DPF filter about 10,000 miles ago. The engine is using no oil or water and neither is contaminated. DO YOU KNOW WHAT THE PROBLEM IS?
Please can you leave a message in the comments section below or reach me via a private message on social media if you can help at all.
Really would like to get this resolved before our next big trip in August.
Thank you very much for watching our videos and for all your support.
Best wishes
Greg & Lou

Видео WE NEED YOUR HELP! There's a problem with our van. канала Greg Virgoe