sprinter 312d engine blowing blue smoke

[lode]

has anyone else had a 5 cyl 312 start to make a small noise like a cam follower and then in about 200 miles start to put out blue smoke? there is no loss of power and the engine still starts fine but you cannot see behind for blue smoke. this has happened to me with two engines one at 127000 and a searls recon at 85000 both had full service history. van went to main dealers and i was told engine was worn out i cannot believe this as it was still going so well in fact better than the engine that i have now fitted. so i intend to take head off to investigate any ideas welcome.jeremy

 

[television]

How clean is the air filter Jeremy

 

[lode]

Hi
Air filter was clean
Jeremy