High pitch sound between 50 and 60

[skippy41]

I have just bought a 36,000 mile superb 2 1.9 tdi, when I get it up to 50 mph, I can hear a high pitch sound similar to that of blowing across the top of a bottle but its continuous until it reaches 60 mph.
if I try to drive at a steady 55 its always there in 5 gear, drop below 50 and it disappears, also over 60
Anyone got any ideas what it could be, and how to rectify it.
This only happens between 1500 and 2000 revs

[adamss24]

Either a boost leak or the turbo is on last legs ! Take the intake pipe and feel the impeller for play, done with the engine turned OFF ! Any small play from side to side is acceptable, in/out play is no good- means wear in bearings. Also too much play means turbo is *****ed and it needs a rebuild !

[GTW]

My Mk1 Superb developed similar recently, but mine was only speed related, not related to rpm at all. After much ado, it's turned out to be wind noise on my NSF inner door seal.

Gaz

[skippy41]

Depressed the clutch while it was doing it and the sound went away, just thinking DMF???

[adamss24]

Depressing the clutch pedal releases the load on the engine so the turbo goes from "on boost" to "no boost" hence the noise stops ! It could be a dry release bearing but that will make noise when depressing the clutch, not the other way round !