No, I'm not looking to make my car sound like it's got a dump valve.  Or change the air intake etc. to make it sound different...

 

I'm assuming that the Mk2 TDi is like the Mk1 and is a recirculate rather than dump to atmosphere system?

 

If that's that's the case, then I'm wondering why I hear a quiet dump valve like release when I change gear?  It doesn't appear to do it all the time, just sometimes I notice it I guess.

 

 

Regards

 

Tom

You will notice it more at lower speed and lower gear changes. For example, changing from 1st to 2nd. Its quite noticeable in my Mk2 07 TDI.

 

Why?

 

Yes - they are recirc by default, however a certain amount of "process" can be heard, and at lower speeds you have less "environmental" noise (wind and engine), which can mask this sound. Not sure whether you are actually hearing "intake noise" or exhaust noise or, turbo spool up or "gas release"

 

Why am I noticing it more now, than I ever did before?

 

As a car gets older things wear,corrode, etc, and noises will change, which can normally start to indicate things going wrong. I say that because my previous car, a Mondeo 2.2 ST 155 TDI estate, suddenly started to make dump valve noises and it was only when the back box fell off, I realised that it was because the exhaust had rotted through just before the back box. Now, I am not saying there is anything wrong with your vehicle, just that changes in noise could indicate a problem, for example a split turbo pipe of a joint coming apart on the exhaust - I believe there is a clamp joint just behind the turbo, which may be releasing a "whoosh". It wont affect performance per say. It could be the gasket on that joint that has gone.

 

Its worth checking out, due to the type of gas.. .etc

 

Hope you resolve the issue.

The car doesn't have a dump valve but instead uses a variable turbo.

 

So when it needs boost some fins on the exhaust side of the turbo move to spin the turbo. Then when boost is no longer required they move back. Obviously as the pressure changes and drops off etc there will be some noise to be heard.

 

The 1.9 PD105 should have an audible noise from the turbo but without any excessive whoosy or hissy noises.

Whoosing between gear changes I'd check the exhaust system. Whistling noise is normally a leak in the boost system.

Just searched on youtube to give you an idea.

 

Mine sounds just like this:

 

https://www.youtube.com/watch?v=ZE6dxd5-KnY

 

There's a little "tsssst" noise when you let go of the throttle. I don't hear it while driving (maybe because the gear changes are so quick with the DSG) but sat in N if I rev the engine like this I get that noise. I was concerned when I first heard it but I did some googling and seems it's perfectly normal on the PD105.

 

Phil

I get the "tsst" noise on my PD Octy Scout. Only really noticed it when I ditched the original Dunlop SP01's!