You might need to bleed it the old fashioned way by pressing the pedel with the bleed nipple open to get all the air out.
This is *not* recommended, as it often leads to master cylinder seal failure.
Here is a (rather long) post I wrote a few years ago on Leon 1/Toledo 2 brake bleeding.
As far as bleeding goes, I can only give you the whole nine yards, based on experience plus the Haynes golf Mk.4 manual - which you should get hold of if you contemplate any more DIY. Haynes 4169, Golf and Bora 2001-2003.
Sorry this has turned into a bit of a lecture. But there are no safe shortcuts. Anybody reading this who finds a mistake - let me know, I'll repost it and/or get the moderators to make the change. Maybe even make it sticky if we can get all the details right.
Brake and clutch bleeding on the Golf Mk.4 platform
Hydraulic fluid should be changed at intervals of two years or less. The fluid deteriorates by absorbing water over time: mileage is not a factor. If it's more than two years since it was done, aim to change the whole contents of the system. I've not done this on a Mk.4 and don't know the quantity; the change is performed by bleeding in the correct sequence until the fluid coming out of the caliper changes colour. Use Dot 4 hydraulic fluid.
Always keep the fluid level in the reservoir at or near the full mark. If you let air into the system you have to start all over again.
You should run at least 0.25 litres of fluid from each caliper or slave cylinder. You will need more than 1 litre of fluid to complete a full bleed of the system.
It is not recommended to bleed by pumping the pedal, as there have been many instances of master cylinder seals being damaged using this method. If the master cylinder seals are damaged the master cylinder must be replaced.
I understand that people have succeeded in using the pedal method, without damaging the seals, by not pushing the pedal all the way to the floor.
The failure seems to be that the seals are caught and flipped round, so they fail to seal any more. I assume that there is a ridge worn in the master cylinder at the bottom of its normal stroke, which you go past once the resistance of the caliper or slave cylilnder is removed by opening a bleed nipple.
Use a pressure bleeding kit (Gunson Easibleed or equivalent).
The Clutch System
The clutch is fed from the same hydraulic reservoir as the brake system. Its master cylinder is fed from a pipe coming off the reservoir side, a small distance up from the brake connection which is in the bottom. This means that the clutch will fail first if you have a hydraulic leak. This can be a warning sign - if you get clutch disengagement problems, check the hydraulic fluid level.
The clutch will need to be bled if you change the slave cylinder on the gearbox or if air gets in by letting the level get too low. There is only one bleed nipple, at the slave cylinder end.
For cars with a five speed gearbox the slave cylinder is on the outside of the gearbox with an obvious bleed nipple.
The six speed gearbox has the slave cylinder integrated with the release bearing, inside the bellhousing and mounted around the gearbox input shaft. There is a bleed nipple on the outside of the bellhousing, close to the gearshift mechanism. Pressure bleed, then with the pressure kit still in place, push the pedal down and release it quickly to get any small bubble out of the long pipe to the middle of the bellhousing. Now bleed some more fluid through.
After bleeding, pump the clutch pedal up to pressure before starting the car again.
The Brake System
If you have any doubt at all about there being air in the master cylinder, bleed it first. There are two bleed nipples, one for each circuit. You should then bleed the front left and right calipers simultaneously, then the rear left and right calipers. This is to get any air out of the master-cylinder-to-ABS-unit pipes.
All the manuals say that the correct bleeding sequence depends on the type of ABS system you have installed.
The two possibilities are Mk.20 or Mk.60.
The Mk.20 unit is mounted flat, with the hydraulic unit on top, and has six hydraulic pipe connections on the left-hand face of the hydraulic unit. The two topmost are from the two halves of the master cylinder.
My 2001 Toledo TDI 110 SE had a Mk.20 unit.
The bleeding sequence for the Mk.20 unit is
Right (offside) rear
Left rear
Right front
Left front.
This is furthest-to-nearest, as the ABS unit is on the nearside of the engine compartment.
The Mk.60 is mounted on the nearside wing with the hydraulic unit towards the engine. The two pipes from the master cylinder enter the uppermost side of the hydraulic unit and two pipes go to the rear brakes from the top of the hydraulic unit just below. The pipes to the front brakes are attached to the opposite side of the unit, and can only be seen from the bottom of the engine bay.
My 2004 Toledo TDI 150 Sport had a Mk.60 unit.
The bleeding sequence for the Mk.60 unit is
Left (nearside) front.
Right front
Left rear
Right rear
I assume that this is because the unit is mounted vertically and the front brakes are fed from pipes attached to the lowest part of the unit.
If air has got into the ABS pump then VCDS or a dealers diagnostic computer may be needed to exercise the ABS unit and remove the air bubbles.
