hissing noise turbo/intercooler pipes

[GW]

has an one had any experience of problems with intercooler pipe work?
My 2.0TDI has a hissing air rushing sound from the bottom righthand side of the engine bay. It's difficult to hear but between 1500-2500rpm you can hear as the turbo boost rises and falls.
started to open my window when driving past buildings, as you can here it much better.

any ideas, is this a common fault? its along way to the dealer!

 

[ddc]

Hi GW,

Are you sure this isn't just your waste gate dumping excess boost??

My 1.9 TD toledo hisses at around the same 'ish rpms but it's only excess boost nothing to worry about..

Cheers

DDC

 

[loadswine]

Sounds like it could be a boost leak. Check the pipes and unions if you can, otherwise , yes its to a dealer.
I had something similar on my last car , that was a turbo diesel and the intercooler to manifold pipe got caught by a tree branch that had flicked up under the engine bay and split. Hissing all over the place when boost started to build. Got a new pipe and fixed. You can't normally hear turbo wastegates on the TDIs as the blow off valves are recirc type and pretty discreet.

 

[Viking]

Hi GW,

Are you sure this isn't just your waste gate dumping excess boost??

My 1.9 TD toledo hisses at around the same 'ish rpms but it's only excess boost nothing to worry about..

Cheers

DDC

You don't have a wastegate on your car, nor on the 2.0 ltr tdi engine.

 

[Richie D]

Have you checked your oil level lately? The turbo can dry out and make similar noises when the bearings are on the way out.

Rich

 

[ddc]

Hi Viking,

If there is no waste gate, where does the "waste gate" like sound come from when I change gear after accelerating hard?? Really sounds like boost dump (with the window open!!!)

Cheers

DDC

 

[muddyboots]

The TDI engines don't use wastegates, they use VNT turbos.
Also, you can't get boost dump (or use dump valves) on TDIs, because there is no throttle

The hissing sounds like a intake pipe popped apart or split somewhere. You'll probably be getting more smoke too.

 

[markirel]

Mine wooshes as well when I change gear and feels like it has lost some 00mph. Are there any specific culprits for split pipes or area's I should look at?

 

[muddyboots]

If you get the hissing when accelerating, it's most likely a leak.

If it's when lifting off to change gear, I believe this may be the sound of exhaust gas flowing over the VNT vanes as they move to a different position which is nothing to worry about.

 

[markirel]

If it's when lifting off to change gear, I believe this may be the sound of exhaust gas flowing over the VNT vanes.

That's probably it then (hopefully), the perception of lost 00mph is probably just over familiarity with the car!

 

[Viking]

If there is no waste gate, where does the "waste gate" like sound come from when I change gear after accelerating hard?? Really sounds like boost dump (with the window open!!!)

Not certain what you mean to be honest, unless it's the turbine spinning down, which you wouldn't hear for the engine noise when booting it.

For interest, this page shows the workings of a VNT turbo. There's a nice animated gif at the end showing the vnt movement which changes the angle of attack on the turbo impellor.

Instead of making full boost all the time, and losing it via a wastegate when it's not required, the VNT makes a controlled amount of boost as required.

 

[muddyboots]

I think it's the noise of the exhaust gases flowing over the VNT vanes as they change position.

 

[ddc]

Not certain what you mean to be honest, unless it's the turbine spinning down, which you wouldn't hear for the engine noise when booting it.

For interest, this page

Cool site Viking, thanks...

Whatever is making the woosh on the gear change.. It makes me smile!!

Cheers

Dave

 

[GW]

Loose Intercooler pipe

thanks for all your help, last Saturday Westgate refitted a leaking intercooler hose.

car now better than ever

 

[III]

Hi There,

I have a 1.9 tdi and seem to have the same hissing noise. If it is the same problem is it serious or can it wait for a few weeks?

Thanks