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Discussion Starter #21
Is it necessary to bleed all around if I’m only going to be opening up the front lines only?
 

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Is it necessary to bleed all around if I’m only going to be opening up the front lines only?
Probably not, as long as you're careful not to let the reservoir drop too low that is! But if you keep the level up at least halfway minimum (and careful, there's more than one chamber in there!) then you can probably bleed just the fronts without touching the rears.
 

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YES, Bleed all four corners as the normal cycle is every two years for flushing out brake fluid on BMWs. RR, LR, RF, LF
Buy a pressure bleeder and use the "Dry" method of filling up the master and using the pump to pressurize the master to 20 PSI, crack open the bleeder screws and check the fill line in the master frequently noticing where the min line is at. Refill as necessary. Do it twice and smack the caliper with a soft mallet to release any bubbles. Road test, then re-bleed as all the air trapped will have moved into the calipers.
IF you can not get the pedal to harden up, you will need to have a scanner trip the ABS System bleeding process (Activate the ABS with the port open, pump the pedal 5 times and the re-bleed each point). Simple, instructions in the TIS.
 

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34 00 050 Bleeding brake system with DSC3
Note:
Read and comply with General Information.
The following filling and bleeding instructions must be observed when the following are replaced or repaired:
  1. Brake master cylinder
  2. hydraulic unit DSC3
  3. Components and connecting lines which are fitted between these assemblies.

Caution!
All vehicles with DSC without precharging pumps must be filled with the new DOT4 low-viscosity brake fluid!
All other models can be filled with the same brake fluid.

Connect DIS.
Call up service function ”Bleeding ABS/DSC3 Hydraulics”.
Connect brake fluid changer to expansion tank and switch on.
Note:
Check relevant operating instructions for each device.
Charging pressure should not exceed 2 bar.

Flushing brake system completely
Connect bleeder hose with collecting tray to bleeder valve on rear right brake caliper.
Open bleeder valve and purge until clear, bubble-free brake fluid emerges.
Close bleeder valve.
Follow same procedure on wheel brakes rear left, front right and front left.

Bleeding rear-axle brake circuit
Connect bleeder hose with collecting tray to bleeder valve on rear right brake caliper.
Close bleeder valve.
Run bleeding routine with DIS with bleeder valve open.
After completing the routine, press brake pedal 5 times down to floor; clear bubble-free brake fluid must emerge.
Close bleeder valve.
Repeat procedure at rear left.

Bleeding front-axle brake circuit
Connect bleeder hose with collecting tray to bleeder valve on front right brake caliper.
Close bleeder valve.
Run bleeding routine with DIS with bleeder valve open.
After completing the routine, press brake pedal 5 times down to floor; clear bubble-free brake fluid must emerge.
Close bleeder valve.
Repeat procedure at front left.

Switch off brake fluid changer and remove from expansion tank.
Check brake fluid level.
Close expansion tank.
Note:
Take care of rubber gasket (1) in lid.
 

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for those who have never replaced pad before, here you go...
Clean contact surface (1) of brake piston with brake cleaner and apply a thin coating of brake pad paste.
Clean contact surfaces (1) of T-heads/brake calliper housing with brake cleaner and apply a thin coating of brake pad paste.
Clean contact surface (1) of brake caliper with brake cleaner and apply a thin coating of brake pad paste.
So as not to damage the surface coating, if possible do not mechanically clean the guide surfaces (1) for the brake pads on the brake caliper mounting bracket. Clean guide surfaces (1) with brake cleaner and apply a thin coating of brake pad paste.
So as not to damage the surface coating, if possible do not mechanically clean the guide surfaces (1 and 2) for the brake pads on the brake calliper mounting bracket. Clean guide surfaces (1 and 2) with brake cleaner and apply a thin coating of brake pad paste.
Lightly coat the T-head of the inner brake pad with brake pad paste in area (1 and 2).
Lightly coat the T-head of the outer brake pad with brake pad paste in area (1 and 2).
 

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Quick advice on managing brake fluid during caliper removal. I did the same thing and didn't have anything to hold down the brake pedal and didn't want to make anything just for this. Therefore I simply cut the rubber hoses in the middle (you are discarding them anyhow) and then took a regular construction nail and stuck into the cut hose. I suppose you can find all sort of similar shaped objects (drill bit, metal rod, etc) to stick into the cut hose. This will keep the brake fluid from flowing for as long as you want (just don't step on the brake pedal). Then assemble the new caliper and attach the new brake line to it. At this point all you have to do is disconnect the old cut brake line from the hard line and reconnect the new line. I did that pretty quickly with some brake fluid leaking on my fingers, while I am removing a tightening the line, but was not a problem at all.
 
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