Fiat Coupe Club UK

Car sounding like a hoover

Posted By: Yann

Car sounding like a hoover - 17/09/2019 16:27

Hi,

I’ve recently noticed that my car is noisy when flooring the throttle, above 2500-3000 RPM (once the turbo starts its magic) and sounds like a hoover. If I release the throttle it’s OK.
I checked all the intake pipes (from the turbo to the airbox, from the airbox to the throttle body), cleaned them, refitted them and tightened them correctly but it still sounds like it’s sucking/releasing air somewhere. Maybe it’s normal but I doubt as I don’t remember hearing this sound before.

What could cause this noise ? I noticed the exhaust tailpipe is perforated by rust on the welding but it’s probably not related.

Thanks
Posted By: Blueboyracer

Re: Car sounding like a hoover - 18/09/2019 05:06

Have you checked the filter in the airbox?
It could be an exhaust leak on the downpipe area too
Posted By: Master_Mariner

Re: Car sounding like a hoover - 18/09/2019 10:45

Is your car still running the original (plastic) dump valve?

Are the hoses to it/from it all attached tightly? A leak there could cause some noise.

Regards

MM
Posted By: Yann

Re: Car sounding like a hoover - 20/09/2019 12:33

Originally Posted by BBR
Have you checked the filter in the airbox?
It could be an exhaust leak on the downpipe area too

I didn't check the air filter, will do that next time. Good idea on the downpipe, I removed some nuts few months ago, maybe I messed up with something.
Originally Posted by Master_Mariner
Is your car still running the original (plastic) dump valve?

Are the hoses to it/from it all attached tightly? A leak there could cause some noise.

Regards

MM

Yes, it's the original valve, the hose are tight, one is less tight but it has always been like that.

I was wondering if a faulty dump valve or wastegate could be the cause of the noise ?
Posted By: Master_Mariner

Re: Car sounding like a hoover - 26/09/2019 14:08

Most have upgraded to a metal dump valve - as the plastic one wears out eventually.

Regards
Posted By: krtek

Re: Car sounding like a hoover - 30/09/2019 17:30

Mine is doing the same thing, sounds literally like a vaccuum cleaner going around the track. I've noticed it won't hold boost past 17PSI and the acceleration is uneven when past 80% throttle.
Posted By: RusH

Re: Car sounding like a hoover - 01/10/2019 05:47

I’d say it’s more of a ‘moo’ sound when the standard re-circ starts to fail.

Definitely sounds like the oe unit could be failing.
Posted By: Yann

Re: Car sounding like a hoover - 01/10/2019 20:27

I was on a trackday in August and also had the feeling that the car was missing power and constantly making the noise, maybe it’s worth to change the dump valve (that’s the recirc valve, right ?) then...
Posted By: Anonymous

Re: Car sounding like a hoover - 03/10/2019 11:36

If's it's on the original DV then change it anyway as your first thing to check - the rubber diaphragm will be utterly shot by now - that's what causes the 'mooooo' noise and leak.
Posted By: Yann

Re: Car sounding like a hoover - 03/10/2019 18:36

I tried blowing through it last month when checking the pipes, it wasn’t leaking, at least for a small pressure...
Posted By: Yann

Re: Car sounding like a hoover - 06/11/2019 19:19

I fitted a new dump valve (Febi 102127, original part number 06A 145 710 from VAG, an improvement of the original part number 034 145 710 from VAG that is equivalent to the original Bosch unit in our cars) and it looks like the old one was defective and leaking ; since I have had the car, there was always a "whooshing" when changing gear in boost, whereas it shouldn't. Now it is quiet. The idle was sometimes too high or fluctuating, especially at red lights or stops in town, now it seems to be lower and stable so I will be able to adjust it properly.

I didn't really get the occasion to check if the car was still making a hoover sound above 3000 RPM.
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