since i bought the car it has been making a periodic buzzing sound??? previous owner was clueless.... said it was self leveling suspension.... WHICH IT DOES NOT HAVE!!! haha
anyways its annoying and i dont think its normal....
basically after i turn the car off for about 5-8 minutes it makes this buzzing sound every 20-30 seconds or so???

do i have a vacuum leak or??? any help would be greatly appreciated!

 

oh and if you press the brakes when the cars off it immediately makes the buzzing noise.... and it goes on for a little longer

 

did you get an answer on this? i have the same issue. and now my key sticks when i turn it off - especially if car has been driven a long time. and now the battery is draining from somewhere. i think it's all related, so i would like to hear what info you received. thx.

 

i know its bugging me big time!! im residing to believe that maybe its my brake booster as i heard that they tend too leak on these cars.....
thing is i dont hear anything that would lead me to believe that its that.... plus my brake assist works fine... so.....
any tests i can run??? anyone know what the vacuum reading should be at the booster???

 

I think I have the same problem. When I turn the car off it makes an irritating buzz every 10 seconds or so. I hear it coming from the right side of the engine compartment which is essentially the back end of the motor itself.

I can't tell if its the vacuum tubes there or not, but it also sounds like its coming from the gearbox, which it shouldn't be.

I'm not sure why it does this but there don't seem to be any problems related to it other than the fact that it is extremely annoying.

It only seems to do it when the air intake on the left side is running, which also seems to blow air into the passenger area of the car

 

well if you want to locate the buzzing... its almost directly under your air filter. the pump and all that is there...

but as far as ive learned its making vacuum in the brake booster... and im guessing its not holding vacuum so it keeps on pumping..... only thing i dont get is why the hell does the booster need vacuum after the cars off????

 

same issue here. I have been told by two dealers and an independent mechanic that it is the brake vacuum pump and it is normal. Mine also only started doing this recently.

 

so will a mechanic address this on the forum or do we just keep getting more and more people with the same issue but no idea of what to do?

 

Hey guys, it sounds like your brake vacuum pumps are running for a bit before the car goes to sleep (typically 10 minutes). If the pump is going on/off like that you might have a very small leak in the brake booster, or in the associated vacuum lines. I'd not go so far as to say its normal, ideally the brake booster shouldnt have any leaks. There isnt really a good way to test vacuum at the booster, when the car is running its going to have enough vacuum to overcome most leaks. What you can do it listen under the drivers dash for the sound of air leaking, and also when you push on the brake pedal. If you hear a constant hissing then its pretty safe to say the brake booster is leaking.

The main reason the pump stays active after the car is off is for safety, if you were ever in a situation where the engine shut off, the vacuum pump will still be there to provide safe braking effort.

 

The electronic valve inline could also be bad/broken.

 

well i tried the method of listening to hissing under the dash i didnt hear any leaks.
but a leak will still show up as less vacuum than usual wont it???

and what actually leaks in the brake booster??? gasket, seal? i mean i doubt its the booster itself right??

im thinking what if i disconnect the pump? will it allow me to pinpoint the culprit or would it just not even allow the car to start???
any thing i should watch out for???

 

The diaphram inside the brake booster goes bad.
If you just disconnect the pump you might have a hard brake pedal.
Have you followed the hoses yet and found the plastic valve inline with an electrical connector? Make sure the top half is not broke and hanging off.

 

yeah mine is okay. when i went to discover the noise i took it all out and all seems to be in good condition nothing was broken but yeah i think i might have a leaky booster, gave it a much closer listen and i heard that little hiss.... BAALLLS!!!

wheres the best place to get one? please dont say dealer.

 

My vacuum pump kept running when I put the key in ignition. I tested by pulling the tube that goes to the brake booster and covering the brake booster switch with my finger. The pump did not stop so I figured the switch was bad. Replaced the switch. Now after ignition it pumps for 1 or 2 seconds and then stops. Happy camper.

 

are either of these a big deal and/or need immediate attention? also, on another matter, my mechanic found that the wrong battery had been installed in my 02 S80 causing ac cooling, cruise, dead at startup, etc to just stop. since getting the correct battery with proper power for my car, this issue with the key not turning to off position to release and the sounds has reduced GREATLY!

 

Vacuum pump with mounting components auto. Trans. Fits: S40, V40 | VolvoPartsWebstore.com

 

change the relay should stop

 

if your Vacuum pump blows air out then its knackered

 

pump running after turning car off took pump out and took it apart it was full of dust and rust cleaned it out put it back in the car now pump only go's on when it needs

to to check if your pump is working how it should let the pump run. then pull the air lines apart you should hear a pop from the suction if not then look for leaks then check the oneway valves buy blowing or sucking air in and out.
if still no fault found the pump switch and relay can be under the left hand side wheel arch you will need to jack up car and take the wheel off to make room to get to it . ps remember to check the fuse in the fuse box under the bonnet

job done

 

I found that putting your foot underneath the brake pedal and pulling back a bit will make the noise stop immediately. I may be just masking a problem that will eventually require service, but it eliminates the noise and works for now.