[Mk2] [Turbo] brake woes

[wickermonkey]

Got the end of my tether. I recently changed the front brakes, calipers and discs, for some rotora's from a member and for the last few weeks i have been trying in vein to get them bled.
First i was using a piece of pipe with a non-return valve in it that has worked for me on various cars, but after hours of trying i could still only get the brakes to the point of 2 good hard pushes on the pedal to get some braking but never fully locking on. So i then went out and bought a gunson vacuum kit, works of a compressor, went round all four wheels in case i had got some air in the system but still can get any real braking going on. Is there anything im missing or could something else have broke in the process? Also what are the two bleed valves that are in the frunk? I guess that one is for the ABS but not sure what the other is, would i need to bleed these also?

[Peter Gidden]

The two "bleed" valves in the frunk are thelow and high side AC valves.

Brake systems are not normally difficult to bleed.

Wherabouts are you based?

[wickermonkey]

About 30 miles west of birmingham. Its not the AC valves, on the left hand side where the ABS is there is a bleed valve just to the left hand side and ontop of the wheel arch there is a cylinder about the size of a coke can with a bleed nipple on the end, both connected into the brake system

[Peter Gidden]

Have you worked out where the air is? Clamp off the 4 hoses and then try pedal. If pedal good, air is in the calipers. If the same, air is between master cylinder and hoses.

[wickermonkey]

cheers, i'll try that now

[wickermonkey]

just been out to check again and found that with the ignition off the pedal isnt holding pressure. i can pump it 2.5 times to get it sold but after 5-10 seconds its back to nothing and my foot goes staright down to the floor again

[Peter Gidden]

just been out to check again and found that with the ignition off the pedal isnt holding pressure. i can pump it 2.5 times to get it sold but after 5-10 seconds its back to nothing and my foot goes staright down to the floor again

With the ignition off, your engine is not creating any vacuum, so therefore once you've emptied your brake booster, you've nothing to replace it with.

Apart from discs, pads and calipers, have you disturbed any other part of the braking system? If not, your only issue can be bleeding.

[wickermonkey]

nope, there the only things that i changed. Looks like im going to be spending the next few hours outside trying yet again to get it sorted

[2tmike]

Not sure what you're looking at under the frunk ? The abs pump should have 6 pipes. Supply and return to the master cylinder and 4 lines going to the 4 caliper cylinders...the only 'coke cam' size thinbg I can think of is under the wheel arch and is the water trap for the AC system.
If you're losing the pedal like that it sounds very much like the master cylinder piston seals...

[wickermonkey]

never added a photo so lets see if this has worked

[toxo]

Electronic Brake Force Distribution! Fairly unusual optional extra.

[2tmike]

absolutely no idea what that is....it's nothing at all like mine (rev 5) or what I can remember my rev2 was like..

[wickermonkey]

glad someone knows what it is , would this cause any problems when changing/bleeding the brakes?

[2tmike]

Ahh...for front/rear balance ?

[wickermonkey]

http://d7c.mr2oc.co.uk/know-your-2-know ... bartid=259

[Harold]

glad someone knows what it is , would this cause any problems when changing/bleeding the brakes?

I have EBFD also and haven't had any problems bleeding brakes in the past.

[toxo]

You could also check your pedal for adjustment, there's a guide in the BGB

[Peter Gidden]

cheers, i'll try that now

And the result?

[wickermonkey]

Right, been on holiday so havnt been able to get to do much but i have been banging away and a few more hours of bleeding and im getting somewhere close. All i can think is that there is trapped air in the system somewhere and its only coming slowly. Ive got it now so that i have got full braking pressure after the second push on the pedal. Looks like i know what im going to be doing after work for the next few days.