problem whilst bleeding brakes, please help!

[N3V3T2]

Ok, I have been a bit eager and tried to bleed my brakes the same way I have done on all my other cars (without any prblems), however I now seem to be unable to get any pressure in the brake system.

I have done a search and found that I should have used a pressure bleed and not the old fashioned way of pumping the pedal whilst locking on and off the bleed nipple.

from the search it seems I have either 1) rolled the seal in the master cylinder or 2) got an air block in the ABS. is there any way to tell which one if these I have done or is there anything else that might have happened and the best way to cure the problem would be useful information.

There isn't any air coming out of the lines but there isn't too much fluid either, not like there was when i started anyway, there is some fluid each pump and it squirts out, just not like at the start.

I was meant to be doing a track day on Friday so this is a real problem, any help and advice would be great
Thanks

 

[Saul]

theres two bleed nipples on under the fluid res on the master cylinder, try bleeding them

if not your going to be in need of a new master cylinder

 

[cordobabrendy]

Sounds like you have bled the wrong valve, on the rears (may also be on the fronts, never looked) theres a 1 way valve you bleed iirc as it stops air going back up into the system, you will need to bleed them again and top up. your brakes will still work if presses really hard but will make the car lurch as they will be uneven.

 

[N3V3T2]

Thanks guys, although I got scared and limped the car to the local VW independant garage, as it's the brakes that I'm now not sure what is going on I felt it was better to let some experience sort them out, although when I spoke to them this afternoon they were still unable to get any pressure in the system. finger crossed.

 

[m0rk]

sounds like the MC has gone. was it pissing fluid down the firewall?

 

[G2232]

so can some one tell me why pumping the pedal and using a bleed kit doesn't work?

 

[cordobabrendy]

it does work but if you pump the pedal and have the wrong valve open it lets air into the system rather than just getting bubbled fluid out.

 

[G2232]

right cheers. the reason i ask is cos i changed my pads lastweek and did that but my friend is a mechanic and was with me when i changed them and he didn't say there was anything wrong with doing that

 

[Saul]

if you push the pedal to far down its travel, or too hard, it can roll the seals of the master cylinder over

 

[ibizacupra]

so can some one tell me why pumping the pedal and using a bleed kit doesn't work?

pedal method will have the brake pedal doing a long stroke from top to carpet... which internally to the m/c can damage the piston seal when it travels to ofar. Once seal has gone, your stuffed.

If the seal has gone, engine off, you can pump the pedal up hard as, but sustained pedal pressure and it sinks to the floor.

pressure bleed or vacuum bleed avoids this.

 

[G2232]

right ok then so haow do i know if i have done this?
as my brakes seem a little spongey at the moment

 

[danfr]

i did the old pedal pump technique to my leon the other day and, after reading horror stories here, was very careful not to roll the master cylinder seals by only doing very gentle presses.
however, when all the calipers were bled the pedal was really spongy and sank loads before anything happened. all i needed to do was bleed the master cylinder. a bit fiddly to get to -you have to remove some pipework to get to it - but literally 5mm of pedal travel (+a few more pumps just to be sure) and the brakes are now sharper than ever.
its worth investigating this before you write off the master cylinder seals

 

[andycupra]

i did the old pedal pump technique to my leon the other day and, after reading horror stories here, was very careful not to roll the master cylinder seals by only doing very gentle presses.
however, when all the calipers were bled the pedal was really spongy and sank loads before anything happened. all i needed to do was bleed the master cylinder. a bit fiddly to get to -you have to remove some pipework to get to it - but literally 5mm of pedal travel (+a few more pumps just to be sure) and the brakes are now sharper than ever.
its worth investigating this before you write off the master cylinder seals

to bleed the master cylinder is it done in the same way as the calipers..?
i presume there are some nipples that you bleed. Can you confirm exactly where theses are on the leon? are they vertical near to the offside suspension turret? or are they actually on the cylinder itself?
also what tool did you use?
cheers.

 

[danfr]

yeah theres a bleed nipple on a valve to the the top front of the MC.
if you look under the reservoir you should see the nipple clearly.
i had to remove the intake pipe to get my hand in there but i think i used an 8mm spanner for the bleed nipple and a one man bleeding kit (one way valve+tube type). - oh and i did it with the engine off tho i dunno if that makes a difference.