sprinter diesel smoking

[Johno1]

I have a 311 cdi sprinter which has started to smoke diesel fumes and knock when warm and under load,also the turbo seams to drop out. It is fine before it warms up.

The localmechs have replaced the boost sensor to no avail and are suggesting a dodgy turbo.

I do not think turbo is a prob. p.s have checked inter cooler pipe

 

[dieselman]

First check the EGR valve isn't stuck open and that all the vacuum pipes are attached to the EGR and turbo actuators.
Next up would be a split intake pipe or intercooler.
Turbo vane rings and actuators can be freed off and lubricated. Sometimes a good dose of injector cleaner will work.