E85 Brake Bleeding advice

[portculisz4]

Have just renewed two rear sections of corroded brake pipe, in order to do this the Master Cylinder was to emptied to prevent fluid pouring all over the garage floor whilst the sections to be renewed were cut out. My question - is there any special procedure for brake bleeding especially in relation to the ABS controller.

 

[1536Z4]

I had to use INPA when I did my E86 to get the air out after bleeding the system the normal way . This is the post here https://z4-forum.com/forum/viewtopic.php?f=3&t=129559 . Hope that helps .

 

[portculisz4]

Many thanks for the response and your experience. Have fully bled the system this afternoon and although brakes working still have excessive pedal travel as though there is still air in the system. No detectable leaks anywhere in the pipe work or calipers so I am happy this is not the cause so my worst fear comes to light that there maybe air in the ABS unit. I read the notes in the previous thread listed and would like to know more about the various methods described to remove air from ABS unit. I do not have the INPA unit but info. provided suggests this clears the system by activating the ABS pump, if so where is air evacuated to, is it pushed back into the pipe work (needing an extra round of bleeding again). Also suggestions about forcing the ABS to activate by hard braking, does this really work ?? Your experiences please.

 

[Rockhopper]

Yes, you’ll need to cycle the ABS pump to get rid of air trapped in there and then you’ll need to bleed as normal.

 

[Ewazix]

I've just upgraded to braided stainless hoses, just a tip for the future, there is no need to empty the fluid reservoir (which guarantees air in the ABS) if you simply put some plastic film under the filler cap and tightening it down forming a vacuum that stops fluid leaking. Virtually nothing leaked from my pipe ends and there was no need to activate the ABS when bleeding. I've used this method successfully many times and the brakes are rock solid.

 

[Scooba_Steve]

put some plastic film under the filler cap and tightening it down forming a vacuum

Is it not airtight anyway?

 

[Rockhopper]

No, it will have a breather somewhere otherwise you’ll get a vacuum as the pads wear.

 

[Scooba_Steve]

No, it will have a breather somewhere otherwise you’ll get a vacuum as the pads wear.

That makes sense, I just didn't twig it might have been in the cap

 

[meh92]

When I installed the rebuilt ABS controller I bled the brakes normally using a vacuum bleeder, then I took it to a gravel parking lot and activated the ABS a dozen times and then bled it again. I replaced 100% of the fluid but the pedal still felt soft. There was still air trapped somewhere in the system. I had it bled at a garage that could activate the ABS and the pedal felt better immediately. I saved major bank replacing the controller myself, and the garage bleed was fairly inexpensive. Money well spent for me.

 

[warmasice]

No, it will have a breather somewhere otherwise you’ll get a vacuum as the pads wear.

I thought the cap was a complete seal. Is the a breather in the cap then?

 

[Rockhopper]

They usually have a diaphragm in the cap with a breather on the dry side of it. So unless you put something over the mouth of the reservoir then the diaphragm will just let the fluid drain out if you take a hose off as no vacuum can be formed..

 

[portculisz4]

Gentlemen - thank you for all your informative responses. Took the W/E off and then ran through a second full system bleed this morning, a lot of air came out from the O/S rear bleeder so not sure whether this was pushed out from the ABS unit or just air in the beginning of the rear pipe feed that I didn't clear on the first round. Brakes now feel solid and back to normal, although I drained the reservoir (which I now know I didn't need to) before starting the pipe replacement there must have been enough in the bottom of the reservoir to ensure the ABS unit did not drain and draw in air. One final question, if there is air in the ABS would show a fault code ??

 

[1536Z4]

if there is air in the ABS would show a fault code ??

Glad you got it sorted . In my case I didn`t get a fault code .

 

[portculisz4]

A final question for my future reference - if you have encountered the situation of needing to purge the ABS unit of air, on cycling the ABS pump I assume the expelled air now moves from ABS unit into the brake pipe network which now requires a total re-bleed at all four calipers. If this is the case, then I assume the procedure would be to bleed the brake pipe network first, then cycle the ABS pump, then re-bleed the brake pipe network again. Am I on the right track ??

 

[colb]

Yes that the way to bleed the system, all wheels first starting with the longest run at the rear which will be the rear offside (right) followed by rear nearside (left), front nearside right then front offside (right). Cycle ABS using INPA then re-bleed all wheels as you did first time around.
Just make sure the master reservoir is kept topped up when you are bleeding.