'Honking' diverter valve ...?!

[andrewd]

The diverter valve on my S4 started making noises variously described as 'monkey noises', 'honking' and 'blowing over the top of a bottle' when boost was at an indicated 0.9 bar (abs) a few weeks back. I decided to swap the aged original one for a spanking new S3 (710N) valve and that seems to be doing exactly the same thing.

Seems it's not staying shut when the pressure in the inlet is approaching atmospheric pressure ..? Any ideas what might be up? Checked all the inlet/boost pipework and they are as tight as ever, and boost is still ultra strong!

[PeteRR]

Might not be the diverter valve at all then.
Is it any worse when the car is hot or cold?
Apparently it's fairly common for air to escape past the Crankshaft rear seal. Leading to similar noises you describe. Worth checking (somehow!)

[andrewd]

Eek! Not suspected anything like that! Although if there was an engine seal problem I'd expect the noise to increase as boost pressure increased?

Still suspect something DV related as the noise is identical to the noise my '97 Impreza Turbo made when the DV was faulty (a common problem for that year), and occurs under identical conditions ... hmm.

[Ski]

i had same issue. I replaced the valve with OEM one but noise is still there.

seems we are in same shoes.