VW Golf MK3 Brake bleeding.

[tome30]

1997 1.8 cl with ADZ engine

I have just replaced the rear brake lines, one from the pressure regulator to right side flexihose (Before it goes on to the subframe) and left side from flexihose to calliper (Drum brakes).

The problem is I can't now get them to bleed.

I removed the old lines with the new ones in situ, so there was minimal loss of fluid and I could attach everything quickly.
Before I attached the rear most flange nuts on the new line, I let the fluid gravity feed and drip out. Essentially filling the new lines.
I had checked the bleed nipples on both sides before doing any work, and fluid came out.
I made sure the reservoir never dropped below minimum.
I had to remove the spring from the pressure regulator to gain access to a flexi hose, but its back exactly where it was as the rust marked the previous position nicely.
I bought a tyre pressured 'one man' bleed kit, and have had it attached to a spare tyre at approx 15-20 psi.
I've tried this with the pressure regulator pulled down, pushed up but nothing.
Brake pedal is firm as it should be, the car brakes, and if I spin the rear wheels and apply the foot brake they stop.

BUT I can't get them to bleed...no air...no fluid...no nothing from my nipples.
What have I missed? Going crazy here.

Thanks

[bigdaz]

Sounds like you need to bleed the master cylinder

[tome30]

Can you explain.
I don't understand how. While working carefully with minimal spillage, at the rear of the car, which so happened to be jacked up. (so any air surely would go away from the master)

I'm not disputing your comment, just trying to understand it more.

thanks.

[bigdaz]

In theory if the brake fluid reservoir wasn't empty bleeding should Be easy but for some reason if the hose hasn't been clamped of they can be a git I think vw recommend the use of a pressure bleeder and if it has abs and that has air in it then you have to use vag com to bleed it, why there such a curse word I don't know but I know they can be with out the right gear

[tome30]

OK
How would I tell if it does need bleeding?

[bigdaz]

If you trying to bleed it with the back jacked up try bleeding it with the car level, and on the master cylinder there's two nipples one for the front and one for the rear

[tome30]

OK will reset my brain and try tomorrow. Methodically.
With a pressure bleeder,should I just be pressurizing the system and opening the furthest bleed nipple?
And when they say the pressure proportioning unit should be open, what does open mean?

[bigdaz]

The leaver has to be held towards the back of the car I think, to get maximum flow

[steveo3002]

look at the valve..you need to clamp it fully in the direction it would be if the car was fully loaded

the rears don't seem that keen to bleed on the ones ive had , so make sure the valve is fully rammed into the loaded position and maybe try a little more pressure like 25psi

[Stu]

I've had this on a few VWs with the rear pressure bias valve. I've generally found if you lubricate the valve a little to free it up, then clamp / tie it full open (so as if car is heavily loaded) that helps. Also, attach the pressure bleeder at standard pressure or slightly higher, but also have an assistant stamp on the brake pedal a few times whilst you undo the rear bleed nipples to force a bit more pressure through.

If that doesn't work, carefully (chock wheels, make sure it's in neutral etc.) try it with the engine running to give some servo pressure. Also, does the car have ABS? I've had all kinds of brake bleeding fun over the years with many 80s/90s/00s VWs and the methods above have always sorted it, along with the usual amount of swearing, brake fluid squirting all over you, bits of rust going in your eyes etc. Good luck!

[tome30]

Thanks guys, sorry to reply late, I've been working a lot.
The car passed it's mot which I'm right chuffed about as it was my first time replacing brake lines. The brakes passed at something like 2.1 front, and 1.8 back. However I still haven't managed to bleed the rears.
I'll have another go when I get the chance.
I have a pressure bleeder (at 25 odd psi) and have forced the valve, but no joy.