For the past year I have had a frustrating WHOOSH/Whistle on boost from about 3rd gear of full throttle through the gears.

Removed EGR:

Eliminated possible "whoosh" through EGR pipe

I have checked for boost leaks:

Found 1 leak after pressure test: light hissing on joint (bottom pipe, one tooth worn on coupler?)

I bodged this with sealant and for approx 3 days..

Test drove and car felt lively, went well through the gears without a whistle/very faint whoosh for at least 100 miles

3 days later, whoosh returns/less power: (thought sealant could have dispersed/worn away?)

On inspection boost pipe hanging loose:

Replaced bottom boost pipe with second hand one..

Drove ~5 miles: Whoosh returns/less power

On inspection boost pipe hanging loose:

Replaced coupler on bottom boost pipe, fits sound with fresh seals.

Drove ~3 miles: Whoosh/No change/less power

On Inspection boost pipe fitting fine, snug in intercooler joint

Boost test:

No leaks

Tested TWO other Fabia's:

105k BLT Engine 2006: Faint whistle on boost (similar to when I bodged joint with sealant)..lots of power

67k BLT Engine 2007: No whistle on boost, Lots of power

Ok people...what's going on?!!

PS: Can I add that I've not eliminated possible variable vane issues on the turbo (eg sticky vanes) as I am unable to do so!

Have you considered pressurising the system (boost pipe test) with smoke in there (like what plummers use ?)

I've got some smoke pellets but I've evaded using them because I am not sure where I can put one when testing as by the time I've secured the pipe to test, I imagine the smoke will have dispersed. Also I'm worried it will burn a hole!!

good point

OMG, what's your secret, there are infants on here who would KILL for those sound FX as they drive down the chippy!

Here's an old tip i've used before now.

2 parts washing up liquid to 1 part water.

Liberally apply to the joints.

Quick whizz around the block, aim for WOT.

Pull up, look at each joint for signs of bubbles.

Update:

I tested the system with 10PSI with Smoke in the system.. Held well and no smoke leaking from anywhere at all.

Here's an old tip i've used before now.

2 parts washing up liquid to 1 part water.

Liberally apply to the joints.

Quick whizz around the block, aim for WOT.

Pull up, look at each joint for signs of bubbles.

- Done this many times..nothing found.

There has to be something so simple surely?!

At that point I would have suspected an EGR, but you've deleted it.

Are you sure your EGR blanking plate on the manifold is making a good seal?

Whilst you're looking, make sure the exhaust manifold and down pipe seals, and that they haven't got any signs of cracks. They have been known to fail before, either at the gasket or the manifold and that could be it.

Next up?

If you're sure the boost pipes are good and it holds pressure, then you can rule out:

Intercooler

Boost pipes (and anything post-turbo to intake manifold)

So you should start looking at pre-turbo pipework. Check your TIP, and pipework to the airbox. A bad seal anywhere there will cause a whistle on induction.

After proving all those are good... Then i'd start suspecting turbo. Or... Listen to your vacuum box. There's a possibility that your vacuum box could have a leak, they've been known to fail before. People have complained of a buzzing sound on the box even after the car has been turned off.

That's all I can think of right now, i'm sure i'll come up with more at some point.

ok well I did the egr delete as I suspected it could have been that so the seal on the egr manifold is fine.

now it's funny you mention exhaust side because the noise tends to get worse as you drive the car more and heat it up so this is my next suspect.

is there any way of pressure testing the exhaust side?

how easy is it to remove the turbo from the car.. would I need to remove the engine?

I'll try the air box too.

oh and the vacuum box does buzz but only since I've done my egr delete.

but it can't be that surely as the whistle is so loud it reflects off cars and the road

Which EGR delete did you use?

I had much the same, using the egr delete from the group buy, firstly the included bolts were too short and didnt tighten sufficiently then the rubber gasket blew out causing a leak. I checked pipework for ages before spotting where the leak was!

Oh and mine would only leak under full boost so didnt show up under a low pressure 10-15psi smoke test.

It would really leak at full 1.6/7 bar

but it can't be that surely as the whistle is so loud it reflects off cars and the road

Still not resolved eh? I'm free next week if you want to pick up that EGR and maybe we can compare whoosh sounds haha

it's an allard delete kit... to be honest I think I'll take that off. seals perfectly well and the noise and loss of power has been around way before the egr delete.

sounds like a plan Danny

gave it a good thrash this evening. boosts well so must have fixed my leak But only to a point because once you go up and down through the gears e.g. twisty country lanes the whoosh returns major style.

so I'm thinking... exhaust end... it's getting hot... perhaps there is a crack or a bad gasket and its expanding, fumes are escaping ( the whoosh sound) and boost is dropping.

where do I start with the exhaust side of the charge system?

Boost wouldn't really drop that much if you had a cracked exhaust, not unless it was the manifold itself, you'd just have a toxic cabin!

Hmm..well what else can it be when its heated up lots..loosing boost with a horrible whooshing sound..till it cools and goes 'ok'??

Did you take the EGR feed pipe off when you deleted the EGR??

Yea blanked off at manifold!

I'm gonna start saying...

If you're only getting it at temperature then suspect anything on exhaust side. Outlet manifold, outlet manifold gasket, turbo housing (exhaust side), head, downpipe, or a join along the exhaust.

If it's accompanied by a lack of boost? Ignore the downpipe/exhaust items unless it's coming from a limp mode state.

Time to start looking at the exhaust end, make sure all your gaskets/manifolds are good too.

I've had this problem on my Fabia as well but it turned out to be the elbow pipe coming off the turbo had a small but prominent crack, I would reccomend taking off the pipes completely and inspecting in daylight. You may find a small but crucial crack. Also, the original manufacturers pipework is really only good until you start tinkering with it. After you've done that i've found it very difficult for the pipes to still hold pressure.

muddin you have dug up some old posts here!

I would love to find a CHEAP alternative to the rubbish standard boost pipes... no luck yet!