Short hiss from 03 V70 brakes.

jbrown122 · Post by **jbrown122** » 12 Oct 2011, 10:38

When pushing the brakes on my 03 at idle, there is a short (about 2 second) hiss from the booster I'm assuming. Brakes still feel fine.. Am I looking at a new booster soon, or can I stop worrying?

jda2000 · Post by **jda2000** » 13 Oct 2011, 09:04

need new brake booster, it will get worst with time

Post by **dan777** » 13 Oct 2011, 23:09

I had the same issue since I bought the car 2 years ago at 75k km. Now at 130k km is doing the same thing and the brakes are still OK, maybe that's the way it is...

carboncow · Post by **carboncow** » 14 Oct 2011, 20:46

our 2001 T5 has this issue too and it comes and goes. I know the right thing todo is to replace it but just haven't got that far. It's a minor PIA project and hopefully your don't have DTCS as that booster is pricey.

I can tell you up to this point after two years it has not effected braking but...

We had the car towed for a bad alternator this summer. They put it on flat bed and then when they backed it off there was no booster pressure and it scared the nuts off me when backing it down. not sure why the tow guy allowed me to do it! I attributed this concern to the leak allowing any residual boost to be gone...so I had to pump like mad. Something ain't right in my no-power senario.

I've been having trouble keeping up with our two volvo's and their constant maintenance needs so the brake booster has been getting delayed...bad volvo owner.

Post by **dan777** » 15 Oct 2011, 08:49

If you backed the car with key on and no brakes that means the vacuum pump (which should give you vacuum when the key is on but engine off) didn't start because either the fuse is blown or the vacuum switch is bad or even worse, the pump is gone. I have the same issue with no brakes when engine is cold, I replaced the vacuum switch so far with no result so probably my pump is bad ($300...).
If you backed up the car with key off then the existing vacuum in the system is gone after you pump the brakes couple times even without a leak, but this is normal I suppose...

carboncow · Post by **carboncow** » 15 Oct 2011, 09:19

The car was off (no key) as the battery was dead.

Shouldn't there still be stopping with a very hard brake (no assist)?

Post by **dan777** » 15 Oct 2011, 10:28

Yes, the brake pedal feels very hard with "no assist" and stopping is very poor and for some reason it feels even worse when you are backing...

carboncow · Post by **carboncow** » 15 Oct 2011, 10:31

Understood on worse being backing. I seem to recall the pedal going to the floor the first time and then a couple pumps getting me there 50% but not hard (ever) or stopping. So I wondered if that was the concern of something else.

I thought the whole concept of power assist was it's just as effective stopping w/o it...it just takes a lot more pressure to the floor from the leg to get the same reaction!

Sorry for hijacking the thread but I think the OP got what he needed.