Sinking pedal

[retro]

Right then, my mk1 VRS has been sat in the garage since November gathering dust and tomorrow I'm going to have a go at getting it going again as I need to sell it.

 

Now prepare for a long back story!

 

November I fitted brand new front Octavia flexi hoses, Octavia VRS refurbished carriers and calipers with new seal kit, brembo 312mm discs and pads. This was great for a week until a rear caliper seal decided to let go when I was driving, I managed to limp home. There I clamped the hose off and removed the caliper, the next day I went to Euro car parts and got a refurbed pagid caliper and fitted that. I bled the brakes using the half pressing the pedal method, this didn't seem to get all of the air out. So I went and bought an ezi bleed kit, I bled it 3 times and could get no more air out of it.

 

Now the problem, I can press the pedal with the engine off and it is rock solid, the moment I start the engine the pedal sinks to the floor and the brakes don't work properly, if I pump them a few times the pedal goes hard then slowly goes soft again. The brakes don't work unless I pump them.

 

What is the most likely cause/repair?

Edited 5 April, 2019 by retro

[sepulchrave]

You need to bleed the ABS block using VCDS, you also need to check the NRV in the brake servo line and also check for vacuum leaks.

[retro]

All sorted, got a guy to come over with VCDS on his laptop, needed to be bled 4 times front and back as there was that much air in the ABS! Time to sell the car now.

 

The guys name was Greg, he was a really nice guy and I would definitely recommend him.

 

https://www.ebay.co.uk/itm/VCDS-Diagnostic-Service-AUDI-VW-SKODA-coding-scan-program-WORCESTER/162462860714?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3D72317524fbb04e07a41d9f403c4bcec0%26pid%3D100675%26rk%3D5%26rkt%3D15%26sd%3D293034758226%26itm%3D162462860714&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3Af1df7c6a-5889-11e9-910e-74dbd18086d6|parentrq%3Af380fb551690aad37a978666fff76ac8|iid%3A1

Edited 6 April, 2019 by retro

[J.R.]

I had my MK1 for 14 years and it was so reliable I never needed VCDS but now I realise that I actually did, when I changed the brake fluid I never really 100% got back the original pedal feel, VCDS may have made the difference, what did make a lot of difference was finding that there are in fact 2 bleed nipples on the master cylinder, you crack them open and a lot of air came out in my case, then simply close them, no tube or jam jar needed just a bit of rag.

 

I ended up scrapping the car because of central locking problems like another poster has, was doing loads of fault finding on the can bus without realising that VCDS would have led me directly to the fault.

 

You live and learn, I so miss the MK1.

[Breezy_Pete]

You should buy another.

 

[retro]

3 hours ago, J.R. said:

I had my MK1 for 14 years and it was so reliable I never needed VCDS but now I realise that I actually did, when I changed the brake fluid I never really 100% got back the original pedal feel, VCDS may have made the difference, what did make a lot of difference was finding that there are in fact 2 bleed nipples on the master cylinder, you crack them open and a lot of air came out in my case, then simply close them, no tube or jam jar needed just a bit of rag.

 

I ended up scrapping the car because of central locking problems like another poster has, was doing loads of fault finding on the can bus without realising that VCDS would have led me directly to the fault.

 

You live and learn, I so miss the MK1.

Well I just so have one for sale haha.

[VWD]

On 05/04/2019 at 21:09, sepulchrave said:

You need to bleed the ABS block using VCDS, you also need to check the NRV in the brake servo line and also check for vacuum leaks.

Interesting. I've had air in system since I had rear shoe change. I even had a so called VAG indie bleed the system .Took them nigh on an hour, but thee's still air .( nOT MUCH,BUT ENOUGH) Could well be my problem .

[retro]

23 hours ago, VWD said:

Interesting. I've had air in system since I had rear shoe change. I even had a so called VAG indie bleed the system .Took them nigh on an hour, but thee's still air .( nOT MUCH,BUT ENOUGH) Could well be my problem .

It took four attempts and three people to bleed it with all of the wheels off. I had to constantly top up the reservoir when the pedal was being pushed as it drained that quickly the first time the fronts were bled it emptied the reservoir.