V70: Wheels/Brakes Spongy brake pedal after changing pads and disks

[John Child]

I changed my front brake disks and pads on my 2012 V70 D3 yesterday and subsequently found that I have a spongy brake pedal. When I start the car I find that the pedal can go straight to the floor but if I pump it a couple of times it is ok. However it will then loose pressure shortly after. When fitting the brakes I did not bleed them as the pistons were able to move back easily and the you tube links I watched did not show that this was required. I changed the rear pads and disks a couple of weeks ago and I did not experience this problem. Any help is greatly appreciated.

[Whyman]

Try bleeding the fronts.

It is always worth pumping out the fluid in the pistons at each pad change as it works hard and can deteriorate over time and certainly doesn't help pushing it back into the master cylinder, and it may cure the problem.

[Model flyer]

That definitely sounds like air in the system and will need a thorough bleed front and back. You may have to go around it a couple of times to get a good pedal. Expect to use about a liter of fluid this will give the system a good flush. If it's still the same after bleeding then you may have damaged a seal in the master cylinder when you pushed the pistons back. You should have clamped the flexible hoses and released the bleed nipples before pushing the pistons back . This releases the pressure and any contaminated fluid in the wheel cylinders is expelled. Hope it goes well.

[cheshired5]

OP, if you use youtube as a definitive guide to brake pad changing and you do nothing with fluid changing and bleeding, you shouldn't be working on a braking system.

[pookie]

How did you retract the caliper pistons into the caliper? If you just pushed them back into the caliper, it has been known for the fluid pushed back into the master cylinder to "flip" the rubbers in the bore. When pushing the cylinders into the caliper ALWAYS open the bleed nipple. This will protect the master cylinder.

Salut!

Pookie

[Waynedance]

Work at a garage and see this lots, poor brakes after driveway fixers been at the brakes.

Had a car in last week for an MOT retest and the front pads were only touching two thirds of the disc, they fitted incorrect smaller discs.

As said has been known to take out the brake master cylinder, get the car to a garage if the brakes do not feel right.

Ps. not say the op is as bad as the example above.

[Elmer Fudd]

Originally Posted by pookie

How did you retract the caliper pistons into the caliper? If you just pushed them back into the caliper, it has been known for the fluid pushed back into the master cylinder to "flip" the rubbers in the bore. When pushing the cylinders into the caliper ALWAYS open the bleed nipple. This will protect the master cylinder.

Salut!

Pookie

Hi Pookie,

I've just had new front discs and pads (Borg & Beck) fitted to my 12 plate V70 D5 auto by my local independent dealer. I've now got a very similar situation where the brake pedal feels much spongier than before. I took the car back the next day suspecting that somehow air had gotten into the system, the same guy bled the brakes and showed me there was no air in there? He seemed to think all was OK and that braking efficiency would improve with time?

I was advised these discs come with a coating that takes a while to wear off but I've now done 500 miles and while the brakes seem a little better they are far from what they were... The car brakes OK but you have to use much more pedal pressure than before. Also when I pump the brakes with the engine running the pedal goes hard but then gradually pushes down towards the floor. With the engine off the brake pedal goes rock solid and stays that way - again the mechanic reckons that is normal for an auto and shows the brake servo is working OK but I've never noticed it before (although probably never had the need to pump the brakes before!) Is this normal?

I have spoken to two mechanics about opening the bleed nipples when you push the pistons back in and neither of them had ever heard of doing this? Likewise when I mentioned the rubbers may have 'flipped' if the pads are pushed back without opening the nipples they reckoned they had never heard of this either!

Assuming the rubbers in the master cylinder have reversed,. is there any way this can be fixed or is it a new master cylinder jobbie?

Look forward to hearing back from you or others - thanks!