Hello all,

My S60 2.5T AWD started making this hissing noise a few months ago. It's coming from my brake pedal, but it only makes the noise when I left up off the brake (decompress). It sounds like air leaking out or something. It doesn't interrupt my driving or stopping the car, it's just making this annoying noise. Anyone have any ideas on what it could be?

 

If it was an American made car I would say it is the vacuum brake booster for the power brakes. I am not sure how the power brakes on the Volvo's are powered but if it is it sounds like the diaphragm may have a crack or split causing it to suck air as the pedal returns to a normal position. When you keep the pedal down does it still hiss or only as the pedal returns?

 

yeh that sounds like the brake booster.

 

It only makes the sound when it's returning back to the normal position. Is the brake booster costly to replace?

 

Calita,

I do not know what it would cost to replace it, your car is not very old so I would also be looking for the cause of the brake booster failure. (if that is what is going on) The booster in general won't just fail most of the time it is caused by brake fluid getting sucked into it (bad master cylinder) or engine oil any of these with break down the diaphragm and cause it to fail. Sorry I can not be more helpful, if you have a mechanic you trust see if you can get an estimate. Maybe someone here knows if this is a common problem.

 

Hi

We just went through something like this with our 2003 S60. The problem occurred off/on for almost a year. Seemed to ALWAYS happen when the dealer wasn't open, so by the time I got there, the symptoms had magically cleared up.

In my situation what we had was the hissing noise you mentioned, that progressed to low-level whine that escalated when the brakes were applied or released. It was such an odd noise that we initially though it was steering related, because it seemed to be predominantly happening when we turned the car. Turns out I brake a lot as I turn Because it never happened when the dealer was opened, I took out my video camera the last time it happened with the sound turned up and went for a drive. Then I went under the hood with the camera running to try to pin-point which piece was making the noise.


What I learned was this - The ABS system had two components that could be causing my problem. A valve and the booster. According to our repair technician the valves are known to go, but they don't cause the weird noises we were getting.

So, the garage replaced the booster -about 800$ for the part plus two hours labour. Thank goodness for their VIP warranty. But the did not replace the valve, which is approximately a 75$part plus an hour labour. (canadian prices)

I wasn't 100% convinced that the problem was fixed because my brakes still don't feel "right". The pressure in the pedal varies greatly, my ABS still doesn't seem to be kicking in properly (I was always so impressed with the car's stopping ability, which has greatly diminished while this was going on). And now, two months later, my noise is back :/

So, its back to the garage I go and ask them to take a look and maybe replace the valve and/or booster again.

Good luck

 

Thanks!

I actually just got my car out of the shop this past Tues. They replaced the brake booster, gave me a oil change, and of course charged me for scanning me car...it came up to about $1200. Thank GOD for extended warranties!

So, while the car is in the shop the "Service Engine Systems Required" light came on... and the tech said it was because of my brake sensor. So, they replaced the brake booster and cleared the code and everything was fine. At least I thought it was. Ok, so yesterday the damn light comes back on. Now I have to take the car back to the shop.

 

There is a hissing noise from the brake pedal on my 2002 S60. My ASE certified tech told me it was the brake booster and that it was a $500 part. I asked him if it was absolutely necessary to replace and he said that unless the brake pedal gets really hard to depress, it can be left alone. I'll gladly let it hiss it's little heart out and keep $500 in my pocket. In fact, I think over the past 2 or 3 days, it's hissing less than before.