I need some help please.

If I press down the brake pedal I get a mid range hiss / puff. Sounds like it is coming from the brake pedal itself. If I pump the pedal with the engine switched off, the hiss stops after a couple of pushes. If I start the engine, the puffing hiss returned when I depress the brake pedal, then and only then.

I have not noticed any problems thus far with braking, and I drive in a mountainous region.

I have not seen any error codes thus far.

 

Sounds like your brake booster is bad. You could check the vacuum line, but considering this is your only symptom, it sounds like the diaphragm in the booster is leaking. (i.e. you probably need a new booster)

 

Thanks for your quick reply, can you direct me to a tutorial concerning vacuum line, I have a feeling this may have been "disturbed" during a recent visit to the Volvo Garage. It has only started since the car was in for another matter, people will do anything to get more business these days. I will search.

Thanks again.

 

Sorry Pentax, I don't have a tutorial on it. But open your hood, and on the drivers side firewall you'll see the booster. @ about the 4 o'clock position on the booster, you'll see a check valve coming out with the vacuum line attached to it. If there is a vacuum leak it will be in that line. It could also be a possibility, that your check valve itself is bad. But sans any real symptoms other than the hissing, thats something you'll have to determine. Sorry I can't be of more help brother.

 

I should also note that before you start removing the check valve or the vacuum line you should purge the vacuum. In other words, while the car is shut off, step on the brakes a few times before you begin
.

 

Thanks very much, I will get on to that. As a matter of interest, although I have subscribed to this thread, I am not getting any email notifications.

 

BTW, about those subscription emails, you turn them on by pressing the "User CP" button in the top left section of this page and then going to "Edit Options."

Hope that helps!

 

Thank you for your thoughts, I have tried braking with the engine switched off... my goodness, one does indeed need to press very hard, for almost no result!!

I have never noticed this noise before, but I may be suffering from automotive-hypochondria. I'll keep an ear / eye / foot on it see if braking performance deteriorates, and take action then, living right up in the mountains I will soon find out!

I will post back once I have satisfied myself one way or the other, assuming I am still alive

I changed my notifications, thanks for that tip :-)

 

Yeah, no problem!

Still, I highly recommend contacting your local mechanic about the noise if it bothers you.

 

I will do that if I can find one that will touch an old Volvo, they all seem to be frightened of them. The car just came back from the Volvo main dealers with the noise as an apparent bonus prize, I was thinking they may have damaged the vacuum pipe. The brakes are working as well as ever they have done, which is very well. So maybe I have just become over sensitive, and it was there all the time.

If Volvo did not notice a problem, and there is one, or if it was caused by them, they are clearly not the right people to fix it.