Hi guys, having a bit of a mare with the above vehicle at the mo, replaced both rear wheel cylinders, bled brakes up by foot ie pumping pedal, took for mot and it failed on pedal spongy and sinking to floor.

So i bought a gunson eezi bleed, and have spent the past 2 days bleeding the system to no avail, i have also actuated the ABS pump using vac com as i believe air can become trapped in the pump, but again no joy, there does not appear to be a single trace of air in the system, are these common for reversing the seals in the master cylinder as that is the only conclusion i can draw, the brakes work fantastic, only if you hold pressure on the pedal, it gradualy sinks down, which mr mot tester was not happy about lol

cheers for any advice you may have

I had the same problem with my 110TDI the brakes worked great apart from the fact that a the lights you could sit there and rest your foot on your pedal and the pedal would slowly go to the floor!

I bleed my brakes lots of times but never got rid of this problem, I don’t know how bad yours is but mine never failed the MOT because of it, it was just annoying from my point of view.

I’ve been told that this is a common problem on these cars and is almost normal for them, but having said that my 130pd is fine the pedal is as firm as you could ever wish for.

All I can think of is you could try changing the master cylinder, which was going to be my next thing but the car has gone now!

Or you could fit new brake hoses as these sometimes get weak and expand under pressure thus the pedal going down.

To be fair I would go for the master cylinder option first, they don’t cost a great deal!

Apart from that I really can’t see what else it would be.

Have these got the 2 bleed nipples on the mastercylinder like most other VW/Audi/seat- i had same problem with mine then someone mentioned 2the 2 niplles on side of mastercylinder under reservior and ran a bit of fluid off here and it was great after, have a look ! i couldn't see them on mine till i removed some piping above master cylinder

Edited 12 June, 201016 yr by jskelton555

I had the same problem with my 110TDI the brakes worked great apart from the fact that a the lights you could sit there and rest your foot on your pedal and the pedal would slowly go to the floor!

I bleed my brakes lots of times but never got rid of this problem, I don’t know how bad yours is but mine never failed the MOT because of it, it was just annoying from my point of view.

To be fair I would go for the master cylinder option first, they don’t cost a great deal!

My 110TDI does this too (and has done ever since I have owned it), but has never failed an MOT, it takes some time for the pedal to very slowly sink to the floor. I suspect the seals are a bit borked in the master cylinder. However I have never failed to stop (or thought I might not stop in time) so I have ignored it.

Solution: use handbrake while waiting at traffic lights

Hi guys, having a bit of a mare with the above vehicle at the mo, replaced both rear wheel cylinders, bled brakes up by foot ie pumping pedal, took for mot and it failed on pedal spongy and sinking to floor.

So i bought a gunson eezi bleed, and have spent the past 2 days bleeding the system to no avail, i have also actuated the ABS pump using vac com as i believe air can become trapped in the pump, but again no joy, there does not appear to be a single trace of air in the system, are these common for reversing the seals in the master cylinder as that is the only conclusion i can draw, the brakes work fantastic, only if you hold pressure on the pedal, it gradualy sinks down, which mr mot tester was not happy about lol

cheers for any advice you may have

I have not experienced this with my Skoda. Many years ago however, I had the problem with another car. I drove very briskly into a car park, stopped the car about a foot from a very solid bridge parapet brick wall, and then sat there horrified as the pedal went to the floor just as I stopped the car. That turned out to be a problem with the seals in the master cylinder which were unable to seal against a corroded master cylinder bore and leaked fluid past them. A new master cylinder fixed it.

Others have mentioned passing an MOT with brakes in that condition.

1) I am surprised that any MOT station would pass a vehicle with brakes in such a condition. In the early stages the car will stop before the pedal goes to the floor, but later the condition will worsen and you could eventually find you have no brakes when you really need them.

2) I wouldn't want to drive a car that had brakes I couldn't rely on.

3) If it was proved that you drove a car knowing that the brakes were u/s, you could have problems with your insurance in the event of an accident.

Further to my June 12th post, I was looking through some back issues of the MG Owners Club magazine last night and found the following comments which might be relevant.

"This condition clearly indicates poor sealing within the master cylinder and it can apply following the fitting of a brand new cylinder, new seals to an existing cylinder, or even ...... just having a period of time when the fluid is drained and there is air around the seals." "What may be occuring is that the internal master cylinder seals may not be as flexible as when new.... loose some flexibility when exposed to air."

A possible solution suggested in the article is to "rapidly pump the break pedal for about 10 minutes, then return later and test if there any improvement". It is suggested that this should be carried out for as many sessions as possible over several days. At the end, if there is no improvement then it is suggested that the master cylinder be replaced.

Hi guys, having a bit of a mare with the above vehicle at the mo, replaced both rear wheel cylinders, bled brakes up by foot ie pumping pedal, took for mot and it failed on pedal spongy and sinking to floor.

So i bought a gunson eezi bleed, and have spent the past 2 days bleeding the system to no avail, i have also actuated the ABS pump using vac com as i believe air can become trapped in the pump, but again no joy, there does not appear to be a single trace of air in the system, are these common for reversing the seals in the master cylinder as that is the only conclusion i can draw, the brakes work fantastic, only if you hold pressure on the pedal, it gradualy sinks down, which mr mot tester was not happy about lol

cheers for any advice you may have

Had exactly the same problem as you last year on my 2001 1.9TDi Ambiente (there should be my posts on here about this somewhere), as my rear cylinder actually popped on the MOT ramp!

Managed to get home but brakes were to the floor. I replaced the offending wheel cylinder (offside) and bled with Gunson's Eezibleed, but could not get a decent pedal. The only solution was to fit a new master cylinder, which cured the problem. I think that once the brake pedal has gone to the floor, this inverts the seals for them never to return to their proper seating.

The master cylinder is only about £70ish from TPS so not too expensive.

Dan

I seem to remember that I got the brake slave cylinder replaced under warranty because it just sank to the floor.

One of the problems in using the manual method of brake bleeding using "brake pedal" pumping to bleed the brakes is that the extended pedal travel used in this operation can put the master cylinder seals in the normally "unused" part of the master cylinder bore. This unused portion of the master cylinder is not polished by the normal travel of the piston and may even be tarnished or even corroded. This can damage the seals and give rise to to the sinking pedal syndrome.

Edited 16 June, 201016 yr by vwcabriolet1971

yep sounds like you fecked the seals on the master cylinder by doing the manual brake bleed wich is a big no no on these cars

you shouuld be using the pressurised bleeder and not compresing the pedal

i have a new master cylinder if you need one if its the same as a vrs one

I had this problem on my Ambiente estate with rear drums.

Turned out one of my nearly new rear cylinders had seized. The rear drums were worn, so even with new shoes things were moving a long way.

After fitting new drums and cylinders and replacing a seized handbrake cable my pedal is back at the top and rock solid.