w201 brake fluid- is there a trick to changing it?

[benhogan]

I am starting with the passeger side rear wheel. All I get is air when my assistant pumps the brakes.

Tell me what I am missing. This is what I did-
1. removed the wheel
2. loosened the brake fluid bleed nipple
3. attached a tight fitting clear plastic tube to the nipple
4. opened the hood and overfilled the bf reservoir
5. as the assistant pumped the brakes, I opened the line.
6. brake fluid comes out but the air bubles never stop coming.

the one thing i noticed, when the brake fluid level in the reservoir is in "max" line, fluid does not come out anymore..just air. what the??

any tips are appreciated.

[benhogan]

update-

i noticed that the inner side piston of the brake caliper is not moving. could i possibly have ruined it by pushing it in too far?

please help

[benhogan]

another update-

i took the brake hose off the caliper to see how much volume would come out. nothing but air. dang.

[engatwork]

Using a bright flash light held against the top of the reservoir see if you can see any empty chambers in there. If so then you need to make sure they are full too. Also, I have seen something real similar happen when the clear plastic tubing on the bleed nipple was not as tight as it needed to be, allow air leakage.

[dirtyharry]

if you have ABS you may have to cycle the pump by turning key on/off to get anything to happen.

[RichardM98]

It sounds like you may be getting air in around the threads of the bleed valve. Open the bleed valve NO MORE than one turn. Usually 1/2 to 3/4 gives enough flow.

[Hirnbeiss]

With the pump method, you leave the valve closed until the pedal is depressed. Open the valve on the downstroke, then close it on the upstroke, and repeat. It sounded like you left the valve open the entire time, which allows air to come in on the upstroke.

[engatwork]

^x2

How soon we forget when we use a Motive Power Bleeder.

[benhogan]

Originally Posted by engatwork

^x2

How soon we forget when we use a Motive Power Bleeder.

yeah, that is on the Xmas list. i had the car towed to my indy. better safe than sorry.

[rurlndum]

Make sure the reservoir is getting filled for the rear brake partition. Easy to overlook.

[DieselPaul]

If you have ABS it is tough to bleed without a power bleeder. My friend built one with a chemical sprayer from lowes for under $30. I'll post a how-to when we build another.

[xps]

I just take it to one of those tire places, 1/2hr later...it's done.
They flush all four at the same time using this Wagner machine.

[benhogan]

heard back from my indy....

it was a procedural mistake on my part!
I changed the pads but then decided bleed the brakes before I compressed the new pads in. So there was no fluid to squeeze the pads...all air.

what an idiot i am! whatever the tab is for this repair...i deserve it.

[Hirnbeiss]

What do you mean? You bled the brakes with no rotor in place? That's likely to push the pistons out.
I think the only way you got air in is by leaving the bleed screw open while there was no pressure on the fluid (i.e., when the brake pedal is going up).
Go heels!

[benhogan]

Learned something else too....

I ruined the new pads I put in! When I put the new rotor in, I just wiped down the rotor (casually) and the cosmoline (apparently some was still on it) got absorbed by the pads. So the pads are now contaminated with cosmoline and you now need new pads.

The tab to undo my stupidity was only $200. So the lesson is....really clean off the cosmoline before putting them on.