Thread: D2a Brake Bleed

Brake bleeding.
This needs two people we will call the pumper and nipple controller.
This is for RHD.
1.Top up fluid to max level.
2.Ensure that ignition is OFF.
3.Attach bleed tube to the bleed screw on front brake caliper on the passenger side, submerge
free end in a clear container containing brake fluid.
4.Pumper in drivers seat should apply pressure to brake pedal several times, then apply gentle steady pressure,pumper should tell nipple controler he is ready to start procedure.
5.Nipple controler should now loosen bleed screw to release brake fluid and air,
Pumper depresses the pedal steadily through its full stroke and tells nipple controller the pedal is down.
6. Nipple controller now shuts the nipple, and when shut tells pumper to release the pedal, when pedal is fully up pumper tells nipple controler he is ready to start bleed cycle.
Pedal is now ready to start repeat procedure.
(IMPORTANT after 4 pumps of pedal check/top up reservoir)

Repeat 4<6
procedure until a flow of clean air-free fluid is purged into container,
then whilst holding pedal at end of downward stroke, tighten brake
caliper bleed screw to 10 Nm (7 lbf.ft).
CAUTION: Ensure the fluid in the reservoir
is maintained between the minimum and maximum levels throughout the bleed procedure using new brake fluid.
Top-up brake fluid level to 'MAX' mark.

Continue to bleed in this order next is Driver side front.
Passenger side rear.
Drivers side rear.

Apply brakes and see how much travel is in the pedal approx 25mm is normal if travel is in an acceptable range build press pedal hard and see if it holds a steady force if it does not hold check for leakage.
If pedal takes a few pumps to build and hold pressure rebleed the system from start.
If all ok.
Remove stand(s) and lower vehicle.
Road test vehicle.
Check brake pedal for short firm travel when brakes are applied.

Whilst on road test
If you want to make sure the modulator is bled,
Put the transfer box into low and select HDC,
(A couple of notes HDC will not function above 31mph or if brake or clutch pedals are pressed.)
Accelerate up to 25mph then take your foot fully off the throttle HDC will slow you down to 5mph.

Or Accelerate up to 25mph then take your foot off the throttle and push HDC button to slow down to 5mph.
Repeat the accelerate/HDC cycle 5-6 times or until you have run the Modulator for a minute or so.
Do not press brake pedal it will deactivate the HDC.
You can do this on the flat - no hill required.
Then bleed the brakes again.



Manual Bleed Procedure with Electronic
Diagnostic Tools

NOTE: The electronic diagnostic tool must be
capable of actuating (energizing) the outlet
solenoid valves for each wheel for approximately
10 seconds and activating the pump of the
modulator.
The inlet solenoid valve should be open (de-energized). Both Nanocom and Hawkeye
diagnostic tools can be used to do this.
1. Apply the parking brake and chock the tires.
Turn the ignition OFF.
NOTE: The ignition must remain off for the
initial bleed procedure; energizing the unit during bleeding must be impossible.
2. Perform brake bleed procedure for wet (conventional )module, bleeding the circuit and master
cylinder if required prior to connecting diagnostic equipment.

3. Connect diagnostic equipment to OBDII port.

4. Turn ignition switch ON

5. Push on brake pedal with maximum force (firm
pedal) and hold.

6. Activate the Modulator Bleed function on the diagnostic tool
starting with Passenger Front.

7. Release brake pedal for 5 seconds and run the Power Bleed function
for approximately 5 seconds.

8. Repeat Steps 5 through 7 three additional
times.

9. Perform manual bleed on appropriate wheels.

10. Repeat Steps 5 through 9 for the remaining 3
brake actuators, working in order of Drivers Front, Passenger Rear, Drivers Rear.
NOTE: If a firm brake pedal resistance is felt and
the brake pedal pushes back when the solenoids and pump are simultaneously actuated for each
brake circuit, the system bleed procedure is complete.
If there is no firm pedal resistance,
repeat the bleed procedure and/or look into brake
system defect, (leaks, etc.).
Retry the HDC run procedure.

Ok, thanks!
So it can be done both ways...is there any advantage to doing it the nanocom way? Or disadvantage the manual way?

It depends on equipment and man power

But you still need to do conventional way
first.

If you have tester to do it use it.

Most will bleed well the conventional way.

If not try the HDC then rebleed.

It's all about how the pedal feels after bleed
with engine off a couple if pumps to use up
vacuum in servo then pedal should stiffen approx
25mm travel pedal should be getting firm and
increasing in resistance, if not you have air.
If its air it will bump up with a couple of pumps.
If pedal sinks you have a leak.
It's important to have a good hard press on
the pedal after you bleed to test the system.

a conventional bleed will not bleed the fluid in the abs modulator

All the above comments are good.
Additionally you may need to remove the front caliper and clamp the pistons back. Position the bleed nipple uppermost when bleeding. The passage to the nipple on the fluid side may not be the highest part of the chamber due to the design of the caliper's internal casting. I discovered this during caliper rebuild after I couldn't get a good pedal following the replacement of all 6 brake hoses with braided ones. There was nothing wrong with my calipers apart from thoughtless design or manufacture. Even vacuum bleeding didn't expel this air. I tried all the tricks in the previous posts and used 4 litres of fluid. Finally went from dangerously spongy to almost like a normal vehicle pedal.

Another hint, dont stroke the pedal all the way to the carpet. Stop maybe 50mm back. This prevents the master cylinder pistons passing the normal working distance and being grazed on any debris or corrosion in the bore which might have built up over time. Not every car has service kept up to the fluid. Thats why master cylinders sometimes fail after bleeding the brakes.
Yes, it is extra work but worked for me. It helped reduce that often complained about 'sinking D2 pedal'.
Hope this is some help and good luck with the 2 hoses below the modulator. A real pita to get to...
Season's greetings, Jason.

Thanks everyone for your replies. Regarding the modulator, if i run new fluid through the system until I have clean fluid at each brake will this mean the modulator has clean fluid in it also? If not, will cracking each line of the modulator and bleeding them first solve that problem?
Im pretty sure im only doing the final hoses in braided, although i havent had a good look at the kit, i didnt even know about the ones under the modulator!

If your only replacing the hoses at the calipers with braided hoses then there should be no reason for air to get all the way up to the modulator and beyond.
If you replace the hoses and do a manual bleed all should be ok.
I recently did a customers car, replaced the master cylinder and manual bled the system, all the fluid came out.
I then ran the modulator bleed with Hawkeye and it firms up the brake pedal.