[Jules]

Thanks Ron I was thinking along those "lines" !
It may even be a pipe that needs slightly bending a different way so the tension is different.

It's got to be an assembly issue as it only affects approx 2 in 10 cars

I would like to spray that expanding foam around but that would be an awful mess!

Last year I took a CDTi up to Frank Massey in Preston who specialises in diagnostics & PWM's etc. He even runs Diagnostic courses for garage techs.
He thought it was regulation but we ran out of time to look further.

I would like to swap a high pressure pump assembly from an CDT that doesn't have the Whine to a CDTi ??
Any differences as far as you know. Rail pressure's same as its just a remap?

I'm going to do a visual now on a CDT & CDTi to see if I spot any differences.