No braking power / loose brake pedal

[Naizz]

Hi guys. So my problem started when my 9-5 got fitted with new brake discs and pads. After that the mechanic didint manage to bleed out the brakes and he fitted the main brake cylinder with new seals since he tought that was the problem but no luck. The brake pedal is really loose and you have to pump it to have any kind of effect when the engine is runing, but when the engine is off the pedal needs one stomp and it becomes firm. While pushing the brake pedal while the engine is running there is a hissing sound coming from the region where the red circle is on the picture. Probably from air escaping. Could the problem be in the brake booster or might there be some kind of leakage?

[Digger]

Having had the master cylinder off for new seals you could have a torn diaphragm in the vacuum booster, before you touch that check for vacuum leaks everywhere else around it.

[Naizz]

Thanks, I have to check that out. Ive also read that the problem might be in the vacuum pump. Any idea how I can check that?

[Digger]

From the way you described your problem the vacuum pump is probably working just fine and more than likely you have a big leak that should be easy to find.

The vacuum booster is connected to the mechanical vacuum pump partially hidden behind the ION module. Not the easiest place to work, but you can get a hand in to slip off the rubber line that holds the check valve and touch your finger tip to the open line with the engine running. Don't forget to test your check valve for one way air flow.

Don't know what tobacco prices are in Finland, but here in the states lighting up a cigarette still cost less than buying canned test smoke and a bright flashlight will give you a better contrast and an inspection mirror will give you a better view of the movement in those hard to see places. The leak you're describing should be very easy to spot.

[Naizz]

Thank you very much for the advice, really appreciate it. Tobacco prices my be skyrocketing but there's no price too high when it comes to one's cars wellbeing. Havent had a chance to touch the car in a week due to work so I really hope its just leak. Would be a shame to have to wait another week for a new vacuum booster.

[swisssaabist]

for info in Switzerland a pack of Marlboro or premium brand is around 9$ ,-))

[Naizz]

Well I finally had time to check my car out and noticed that the back brake calipers were installed upside down.... This is what I get for using a cheap mechanic. Lets see if that will solve the problem or if there infact is a leak. Otherwise the noise was just made by air in the system.

[Digger]

Well I finally had time to check my car out and noticed that the back brake calipers were installed upside down.... This is what I get for using a cheap mechanic. Lets see if that will solve the problem or if there infact is a leak. Otherwise the noise was just made by air in the system.

I've been looking at disk brakes for years and I've seen back brakes squeeze the rotor with piston and pad after being put back together without the inside pad. I've seen a rotor cut through a bracket because an axel wasn't bolted on tight and I've seen brakes so bad that the rotor disk was worn off the hub. But I can't picture with my minds eye how these could be put on upside down, that must have taken some serious effort.

[Naizz]

Haha tell me about it. Cant wait for what excuse they come up with. The fact ive never worked on brakes myself and noticed this makes me feel real glad I paid for "professionals" to do the work.

[roblistens]

Perhaps you could finish your story? Would be very interested to hear what "excuse" the mechanic came up with!