Air In Mk2 Tdi Brake System That Won't Go.

[t-aslam]

Hi guys,

I have a 2005 tdi galaxy with 235k on the clock. Last week I made a slight error with bleeding the clutch. Ever since the clutch was changed I have had air in the system resulting in a sticking pedal are partially operative pedal. I purchased an eezibleed kit and hooked it up. There is a clear pickup hose inside the pressurised bottle which attaches to the output side (new fluid pushes through this). I accidently attached it to the input. Fast fizzing Air bubbles emerged through the output and was pushed through the system. So much air pressure has built up that when I disconnected the valve from the pressure source (the tyre) fluid came out of the air hose!!! The reservoir ran dry and hey bingo brakes went totally shit. New brakes all round and 1000 miles on and brakes are still crap. Very spongy and probably half the braking force as before.

I have bled it the conventional way with someone pressing the pedal and me catching the fluid at the bleeder all round and ensuring the fluid never ran lower than max. No luck.

Any ideas would be greatly appreciated.

Thanks.

[t-aslam]

Also forgot to mention slight steering vibration braking at about 30mph and on and off brake effect at very slow braking speeds.

[t-aslam]

Ok, slight improvement after I applied the brakes real hard and got the car to skid. Apparently this has shifted some air out of the abs pump. Still not great but better than earlier.

[viperclive]

You now have to chase that bubble now it's moved out of the abs manifold, I always use a length of clear hose on bleed nipple, that way when bleeding you can detect air bubbles coming out of system.

[seatkid]

Not sure if this the right way

 

http://www.ross-tech.com/vag-com/cars/absbleeding.html

 

Alternatively, get ABS action with ultra hard braking - follow by a conventional bleed.

[sparky Paul]

The best way to get any air out of the ABS pump is to do the full bleed procedure with VAG-COM.

[t-aslam]

Thanks for your quick replies. Sparky, I have VCDS lite, is it possible to do the flush/bleed with this version? I'd rather do it the correct way.

Also just followed that Ross tech link and it seems as if I just have to plug in VCDS and operate the abs unit for a few secs. Then after that do an old fashioned bleed all round.

I also saw another vagcom procedure online which involved having just the front bleeders open and brake pedal pressed 10 times. Don't know if that's the normal procedure with the galaxy too.

Edited October 23, 2013 by t-aslam

[sparky Paul]

IIRC you have to follow the instructions in the link seatkid gave above, then carry out each procedure exactly as and when VAG-COM/VCDS tells you. It's a bit of a pain to do, and you really need two people, but it's the only reliable way to get the air out of the ABS.

 

The other way is to bleed normally, then go for a rally on some loose ground to operate the ABS pump, then bleed again, then repeat as necessary... it should improve the problem, but due to the design of the ABS pump it's unlikely to get all the air out.

[t-aslam]

Excellent thanks!

[t-aslam]

Ok I've bled the abs system and the pedal is a lot firmer. BUT, I have another problem. The steering and in fact the whole car shakes when braking from high speed. Sometimes it is accompanied by a knocking sound from the front right. This only happens when braking and I cannot figure out what it is. The wishbone bushes look fine, the track rod ends were replaced about 60k ago with genuine parts. They don't appear to have any play and neither do the lower ball joints. I also replaced the caliper guide pins and greased them before fitting.

Could it be that the air in the system caused my new discs to warp all round? That's the only thing I can think of.

[xavier]

discs warped would be my first thought, or possibly stuck caliper. Given the relatively minor cost of discs and pads (if DIY-ing) I'd go for that first.

[viperclive]

I know what it is as I had the same problem, it's what everybody forgets about, the inner track rod ends!! A sure sign is if you unwind from track rod end the inner arm should not be floppy, it's a spring loaded ball joint on the end and when it wears it rattles under heavy breaking causing the steering wheel to go nuts, as though you have a warped disc! They are only

[t-aslam]

Viper bro, I assume you're talking about the track rod ends and not the track/tie rods themselves. As mentioned I did replace these not long ago, HOWEVER, as we all know new or newish parts can become problematic before their time.

So what your saying is there should be some resistance at the track rod end ball joint ie it should not twist too easily. Hmmm. Got my MOT tomorrow morning so if it fails on that or advisory on that then we'll be getting somewhere.

And an online pat on the back for you lol.

[viperclive]

That's em we call them lolly pops up north! Because the ball joint sits inside the rubber sleeve it's hard to detect wear.