Help!

 

 

I changed both rear calipers yesterday (new from Eurocarparts)   along with discs and pads -  all PAGID brand.

 

Bled the brakes using VW brake fluid,  and a Sealey pressure bleeder (one man jobbie) - pump up the reservoir,  then undo one nipple at a time.

 

Bled about 1/2- 3/4 litre of fresh fluid thru in total for the new calipers  (long after any signs of air)

 

 

 

Problem is now I have long long brake pedal before any bite,  and brake pedal feels very spongey and very very vague.

Engine on,  and If I press the brake pedal,  the pedal will slowly sink to the floor....  (wasn't like this before)

 

Engine off,  if I press the brake pedal,  it's not rock hard.  It is firm, but spongey with quite a lot of travel, and it starts to sink (but doesn't reach the floor) when I keep it pressed in

 

 

 

Now prior changing the calipers,  the brakes were always great on this car.-

very little travel in the pedal (if any) and good feel.

With engine off,  the pedal would be rock solid - no movement at all when you pressed hard on it.

 

 

 

 

 

So today we jacked up the car,  and rebled the rears.      another litre of VW fluid used,    this time using two man method - press brake, open nipple.     pedal to floor, tighten nipple.      repeat over and over.

 

 

Bled the rears,  about 1litre in total.

 

 

Tried to bleed the front(s) but first nipple was rounded,  so couldn't go any further,   so gave up.

 

 

 

I looked on the master cylinder (reservoir unit) but couldn't see any bleed nipples there (the mk4 GOLF has two bleed nipples on the brake master cylinder which always need bleeding, and often are the cause of air in the system),  but I could not see any bleed nipples on the master cylinder.

 

My question is - why and how do I fix the problem I have now please?

 

reading the above,   how can I improve one the methods I've already used?    and what have I missed ?

 

 

 

 

Ps.  1.9TDI 100bhp,   ATD engine code.

 

 

Haven't read it all, I'm tired, I apologise!

If the pedal is going down to the floor with more pressure you have a leak somewhere.

Ignore, I see you have tried this!

I'd suggest a bleed with two people using the good old method of nipple open, pedal down nipple close, pedal up etc.

The pedal will always feel spongey with new discs and pads anyway. - I think this is your problem, let them bed in for a few days and see how it goes.

Thanks for replying!

 

  I'm not convinced it's down to just new pads and discs - i've actually got very long brake pedal now (no bite till very near the bottom),   which wasn't there before.

 

With regards to bleeding - is there anything that needs to be bled on the master cylinder (Reservoir) itself?

 

I am wondering, because on a Golf mk4,  the master cylinder has two nipples which must be bled, and often are the cause of air in the system.   I could not see any signs of bleed nipples on the master cylinder itself on the Fabia..

No, nothing on the cylinder.

Did the brake fluid go very low at any time or did you keep it topped up?

Used a pressure bleeder, so should be always topped up. If there's no master cylinder nipples, then I guess it's just a game of chasing air out of the calipers?

Would air have found their way into the front brake lines?

Edited 14 March, 201412 yr by Gti Fly

Very doubtful if it's been kept top up as you have said.

To be honest you seem to have went down the ruite of all the basic things to fix this. It's hard to diagnose over a forum and without sitting in the car feeling the pedal myself.

- let them bed in and see if you get any improvements at all

- Could be master cylinder. If you can, blank off all the pipes from it (remove pipe and fit a blank)

The pedal should be solid. Alternatively you could clamp both rear flexi pipes and see if the pedal improves.

Thanks for reply.

How about this then, engine on, press on the brake pedal, long travel (which wasn't like that prior to the brake change last night), then pedal travel mid way goes firm (as pads bite) , and the pedal sinks slowly towards the floor.

Thought the pedal shouldn't slowly sink to the floor once it firms up?

Thanks for reply.

How about this then, engine on, press on the brake pedal, long travel (which wasn't like that prior to the brake change last night), then pedal travel mid way goes firm (as pads bite) , and the pedal sinks slowly towards the floor.

Thought the pedal shouldn't slowly sink to the floor once it firms up?

That's only the servo kicking in mine did that when my cylinders were shot I'd turn it on pedal to floor then up and go to press again it would firm up but the next time there was nothing again!

Ok thanks. I will also bare that in mind.

Just a bit annoying this has all happened as I need the car for a long journey down to the airport and back this weekend.

try removing the rear calipers from the carriers and having the bleed nipple open while tilting the caliper thru a few angles, the nipple is not at the highest point of the caliper especially if you have the rear jacked up, sometimes it is easier to get the last bit of air out by slackening the feed pipe into the caliper and letting a bubble out of there, they can be a right pain to bleed sometimes tho.

you shouldn't have any air in the fronts unless you let the fluid run low.

Thanks, thats certainly worth a go

try removing the rear calipers from the carriers and having the bleed nipple open while tilting the caliper thru a few angles, the nipple is not at the highest point of the caliper especially if you have the rear jacked up, sometimes it is easier to get the last bit of air out by slackening the feed pipe into the caliper and letting a bubble out of there, they can be a right pain to bleed sometimes tho.

you shouldn't have any air in the fronts unless you let the fluid run low.

+1 on this method. You will see a bubble of air come out as you tilt the caliper.

The manual states that you should pre fill the calipers before you fit trhem to prevent this problem.

You could also try winding the piston fully back as well.

Was going to ask about this problem myself as have similar issues and I wasn't overly sure it was purely down to new pads and discs etc.

What would happen if the fluid level got too low and drained from the ABS pump? I know it says you need VCDS to bleed it but what would happen if it had drained?

My brake pedal bite is pretty brutal with the pads that I'm running but the pedal is no where near as firm as it was beforehand and this bothers me.

Oh this removing the rear caliper and tilting method would this also be the case for 256mm rears?

Yes they all do it mate.

How would you know if you need the ABS pump bleeding? Any tell tale signs?

To the OP, one thing, have you gone through the adjustment procedure for the handbrake yet?  If you have not done that, the piston travel will a lot and use up more master cylinder fluid than normal.

Edited 15 March, 201412 yr by rum4mo

Adjustment for handbrake??

I thought the rear calipers are self adjusting? They are the same caliper as Mark4 golfs. They don't need adjusting, just pumping a few times on the brake pedal after First fitting them, before applying any handbrake

More over the hand brake works a Ok too.

So is there something else I need to do to the handbrake?

Put the handbrake on hard and pump the pedal hard.

Gti Fly, in that case you will probably find if you risk driving around a bit, the brakes should improve. One other thing, maybe Pagid did not leave these rebuilt callipers in the correct state, I seem to remember that there was a warning notice with the callipers, but I think that I wound them back "just in case". Fully retracting these pistons now again might improve the brake pedal though as the handbrake works okay maybe there is no need - but why not if you are really stuck, it will only take a few minutes and let you check everything over again as where you are now is no good at all as you have worked out.

 

Did you slacken off the handbrake cable so that you could let the callipers handbrake work properly - I say that as when I replaced only one calliper on my B5 Passat, I had to mess about with the cable to get both sides to work correctly - and that was after not having adjusted the cables at all since the car was new.

 

Out of casual interest only, did you replace the brake pipe O-ring seals - or just reuse the ones that were fitted - I just reused the originals as they did not seem to have suffered any corrosion from road salt, though I had replaced these flexis a few years earlier after getting an advisory at MOT time for a front flexi - garage seem to have "hung" the calliper etc from it while replacing a wheel bearing (thanks VW main dealer!).

Edited 16 March, 201412 yr by rum4mo

Thanks for the replies so far.

I will remove the calipers and lift up and re bleed to see if I can see any tiny air bubble trapped inside.

I've tried pumping brake pedal with the handbrake on, but don't notice any difference afterwards. Pressed brakes and held down very hard, so repeated this several times, would have thought it be enough to get the pistons to set correctly.

Even so, the handbrake works a Ok, and the rear discs and pads are biting nicely, I can see them bedding into the disc surface uniformly. Handbrake lever travel also seems fine too. Same amount of travel and resistance it was prior to me changing the calipers.

I did not change the brake line to caliper crush rings, just reused the existing ones, as they looked fine and I couldn't get them off without cutting them, so left them as they were. I've checked and they aren't weeping or leaking. Dry as a bone.

Basically I'm left now to try and re bleed the rears, I'll try and do with the the caliper unbolt ed from the carrier so I can tease any trace of air out of the caliper. I can't seem to get the front caliper nipple off as it's almost rounded, so I'm now stuck with dilemma, do I drill it out (the rusted bleed nipple) and fit new nipple, or just Sod it and get a pair of refurbished new pagid calipers!

Anyways, car is Ok drivable, managed to get to airport Ok. Away now for a few days, I'll give it a go when I get back later this week

Cheers for the suggestions and tips so far guys

Try bleeding the brakes the "old fashioned way" (one person pressing the pedal, the other cracking the nipple open) but with the engine running. I've come across this with other vwag cars and as it is mentioned in the thread there will be air in the abs pump more than likely. Start bleeding the brakes from the caliper that is fatherest from the master cylinder so if the master cylinder is on the drivers side start passenger rear, drivers rear, passenger front, drivers front. I'm confident this will work as it's happened to me on a mk5 golf.

If you have in the abs block you can use VCDS to remove it.

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Update:

 

fixed problem with another bleeding of rear calipers.

 

 

Hooked up the pressure bleeder (sealey one) same as before (pumped to 25(psi?))  undid one of the rear bleed nipples, and the brake fluid SLOWLY flowed out same as before.   Nothing, no sign of air,  clean fresh yellow fluid.

I hand pumped the brake pedal (whilst the pressure bleeder was still connected) and again,  no air.    bugger.    About 150-200ml of fresh fluid flowing used by now.

 

Got my mate to jump in the car,   and pressed the brake pedal by foot,  FORCEFULLY.  this made the flow of oil out SO MUCH faster.  Suddenly a big air bubble shot out along the clear bleed pipe.   Success!   

 

 

Seems like a combination of pressure pump and also a big hard press by foot is enough to push out the air bubble!

 

I guess the air was maybe trapped in the upward curve of the short rear brake line  (as was mentioned by someone above!)     

 

 

Hope this thread helps people in future that might have similar problem when bleeding brakes/replacing rear calipers.

 

 

Cheers for the help guys