Hi, I posted a message on the general site and nobody came back with a suggestion. Maybe the T5 owners might be able to help. I have a 2003 S60 T5 in pristine condition with 70,000 miles on the clock. In the last week I am getting a hissing noise when I press the brake pedal or let it go, like wise when I let go the accelerator? There is no difference in the braking, it still performs 100% as new. Please somebody tell me it isn't a knackered brake servo? I believe it is savage expensive to replace. I've had a grin on me since I bought the car, but it will disappear very quickly if this is true.

there is always a hissing noise from the servo when pressing the brake as the air goes in through the pedal push rod area but it is normaly very quiet .There is a foam air silencing/filter material inside the rubber boot where the pedal push rod goes through , but it does seem you will need a new sevo to cure from my experience with this noise :-(

Hi, Registers is not the place for Technical questions. Have asked it be moved.. Your other post was actually in the "Blogs"... However, some more detail about what model of car you have would help. Hissing in the dash may relate to the heating system as that uses vacuums to open and close the heater distributor box. Do you have AirCon?? Luck in getting this resolved... :) Welcome to the forums and enjoy your time here... :) Des. . . ;)

Hi, I can only assume Mr Ben has posted some derogatory comment but if you look at the below photo - top right hand part - you will see vacuum tubes to the heater distribution box. If your hissing is definitely coming from the dash area then it may be (as already mentioned) a source of your hissing. Tubes broken or removed or displaced will hiss. But then, how the heater (and heater distribution box) works in your S60 could well be different to how it works in my 940 or V90. Des. . . ;)

Neil, if you do a search in the S60/V70 forum for "brake hiss" you'll find some threads which could be useful, you can compare them to the noise you are getting and go from there. As Clan says though they all seem to suggest a new brake servo is the most likely result. Cheers, John

I to have this hissing coming from the brake servo. I have never actually worked out where in the servo it comes from. Some suggest that a diaphragm is broken but I am not so sure. When I start off in the morning there is no hissing, this only starts after about 15 minutes of driving. While pressing the brake pedal the hissing stops but starts again when the pedal is released, if you then press the pedal relay hard then the hissing will stop for a while. This to me seems more like case of the servo is coming apart and not the diaphragm. I am sure on one of the forums (not sure it was this one) that someone managed to fix it without a new servo, the problem is I can not find it any more.