Hissing noise when braking

[BeeBee]

Any ideas ?
When braking ( and windows partly open ) I’m hearing a hissing noise, sounds like coming from front near side, stops when foot off brake.

 

[BeeBee]

Meant to say it’s a t6 California Ocean , 2019.
And having googled a bit , thinking it’s the brake booster… anyway, other than garage, to determine this ?
Also, would a specialist VW garage be necessary ?

 

[Perfectos]

When does the hiss occur? Every time you break or just sometimes?

It doesn’t correspond with speed bumps does it ?
On a T6, The front suspension makes a distinctive hiss , when it’s compressed, very audible when the window is open

 

[BeeBee]

Hi, it’s every time I depress the brake and not associated with going over bumps. As soon as my foot comes offf the brake ‘ no hissing’
I’ve checked the brake fluid reservoir and seems fine, no visible leaks either.

 

[Perfectos]

Get it checked out , no need for a VW specialist, any Garage / Kwik fit etc should be able to carry out a safety check

 

[Rubinstein]

Hi, it’s every time I depress the brake and not associated with going over bumps. As soon as my foot comes offf the brake ‘ no hissing’
I’ve checked the brake fluid reservoir and seems fine, no visible leaks either.

Sounds like the brake servo. Easy to test in a local garage, particularly one that does mot testing as it’s checked as part of the test. Do it as soon as you can, if the servo fails the brake pedal will be very hard to depress and the vehicle will be unsafe to drive.

 

[BeeBee]

Sounds like the brake servo. Easy to test in a local garage, particularly one that does mot testing as it’s checked as part of the test. Do it as soon as you can, if the servo fails the brake pedal will be very hard to depress and the vehicle will be unsafe to drive.

I was thinking of getting Kwik Fit ( who offer a free brake check ) to initially look at it as they are just a couple of miles away.
My alternative VW dealer is 50 miles each way.
Any thoughts, my concern is the ‘risk factor’ when driving.

 

[ArunAlec]

I was thinking of getting Kwik Fit ( who offer a free brake check ) to initially look at it as they are just a couple of miles away.
My alternative VW dealer is 50 miles each way.
Any thoughts, my concern is the ‘risk

Does the hissing occur when you are stationary with the engine running and foot on brake?
If yes then, you should be able to locate where it’s coming from if you get someone to apply the brake whilst you listen under the bonnet.
If you’ve got breakdown cover and you suspect potential brake failure they might come out…..if no home cover drive it up the road!

 

[BeeBee]

I’ve got VW ‘All In Plan’ covering Road Asst and Warranty.
VW dealership in Edinburgh can see me next week but initial charge to me £132 for diagnostic, thereafter ‘may or indeed may not ‘ be covered by warranty !

 

[Rubinstein]

I was thinking of getting Kwik Fit ( who offer a free brake check ) to initially look at it as they are just a couple of miles away.
My alternative VW dealer is 50 miles each way.
Any thoughts, my concern is the ‘risk factor’ when driving.

It's a difficult one not knowing what the actual cause is. Maybe have a chat with your nearest garage and explain your concerns, they may come out on road test if your close enough to have a look.

 

[Rubinstein]

I’ve got VW ‘All In Plan’ covering Road Asst and Warranty.
VW dealership in Edinburgh can see me next week but initial charge to me £132 for diagnostic, thereafter ‘may or indeed may not ‘ be covered by warranty !

£132 to stick your head in the footwell and have a listen !!!!!
makes my blood boil. Check your warranty details, Brake servo is not a wear and tear item, it should be a simple yes or no on cover

 

[Perfectos]

I’ve got VW ‘All In Plan’ covering Road Asst and Warranty.
VW dealership in Edinburgh can see me next week but initial charge to me £132 for diagnostic, thereafter ‘may or indeed may not ‘ be covered by warranty !

All in plan has VW assist included, ring them and tell them it’s a safety issue with the brakes , they will come out and either confirm no issue , fix it or transport it to the dealer who has to make your repair a high priority (you get a courtesy vehicle included whilst your van is being repaired- no investigation fee if VW assist have already looked at it )

 

[FNQ California]

Any ideas ?
When braking ( and windows partly open ) I’m hearing a hissing noise, sounds like coming from front near side, stops when foot off brake.

Had a similar problem with our Passat, turned out to be a sticky piston in the brake calliper which wore the rotor. I'd have it checked asap.

 

[BeeBee]

All in plan has VW assist included, ring them and tell them it’s a safety issue with the brakes , they will come out and either confirm no issue , fix it or transport it to the dealer who has to make your repair a high priority (you get a courtesy vehicle included whilst your van is being repaired- no investigation fee if VW assist have already looked at it )

Thanks for the suggestion, got VW Assist out at the moment , having a good look at the brakes etc

 

[BeeBee]

Turns out ‘the hissing noise’ was film on the disc pad. Wheel off disc cleaned off , pads checked and all good.
What it did show me was that the rear discs will probably need replaced by the next service, April 2026 as they are showing signs of light corrosion. VW technician said watch out for ‘bump ‘ sound if rear discs and pads failing…. good guy, great service.

Thanks for the ‘heads up’ re safety concern and VW Assist option.

 

[Ian white]

When does the hiss occur? Every time you break or just sometimes?

It doesn’t correspond with speed bumps does it ?
On a T6, The front suspension makes a distinctive hiss , when it’s compressed, very audible when the window is open

Have you got air suspension?

 

[Perfectos]

Have you got air suspension?

No it's a feature of the factory Struts