Thread: D2 - air in the brake lines?

I might be wrong, but I just had a feeling that you couldn't bleed D2 brakes yourself because of the ABS modulator, you had to have it professionally done. I am guessing it has to have so sort of positive pressure to bleed brakes.

Originally Posted by walker

I might be wrong, but I just had a feeling that you couldn't bleed D2 brakes yourself because of the ABS modulator, you had to have it professionally done. I am guessing it has to have so sort of positive pressure to bleed brakes.

From what I understand, you require Testbook to do it if you have replaced the ABS module or anything up the line from the ABS module. But down the line items such as brake hoses should be fine to manual bleed.

Rave outlines the manual bleeding procedure.

Some say you need a nanocom to bleed them,
some say you can do it by tricking the ABS to operate, the so called powerbleed.
I have had two dead pedals, in two different D2's, both in exactly the same spot doing exactly the same thing. Start from cold, select gear, idle off to first T intersection. I put it down to lack of vacuum, so now I drive off and to hell with the neighbours.

Having this exact problem atm and have not been able to push fluid out the front lines, it is in at Lifestyle 4wd atm and it has had all checked or replaced you may want to call Steve Armour as he has been going over and over the problem discussing it with other mechanics in Perth to try and come up with a remedy..(08) 9271 7900

The relay trick just runs the return pump which is effectively what a power bleed does. This won't address problems cause by air trapped in the modulator valving.

There is a full bleed procedure in the WABCO support documentation that can be roughly adapted to the Nanocom/Hawkeye.

I made a start sometime ago on Nanocomising the procedure.I haven't tested the process so feedback is welcome. I'm working on the theory that Land Rover would have followed WABCO tech advice on bleeding.

cheers
Paul

Brake Bleeding Procedure

The following brake bleeding methods explain
how to bleed a hydraulic ABS dry
modulator assembly during installation, or in the
event of air in the brake system. These instructions
are for manual bleeding with electronic diagnostic tool
and include the procedure for bleeding
both the master cylinder and the brake system. In
some cases, for example if you are replacing only
the modulator assembly, it may not be necessary
to bleed the master cylinder.

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
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. (Note: you may be able to use the "test" function for each wheel for this step)

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.

NOTE: To perform a manual bleed, follow
Steps 2 through 8 under “Manual Bleed
Procedure (Wet Modulator Assembly)”

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.).

Wet Modulator Assembly Bleed

1. Apply the parking brake and chock the tires.
   Turn the ignition OFF and disconnect the
   battery terminals.
   
   NOTE: The ignition must remain off for the
   entire bleed procedure; energizing the unit
   during bleeding must be impossible.
2. Fill the reservoir with DOT-approved hydraulic
   brake fluid.
   
3. Depress the brake pedal five times using the
   stroke between 1/3 travel and maximum travel
   in 5 seconds.
   
4. Release the pedal for 5 to 10 seconds. Air
   bubbles will rise into the reservoir while
   depressing and releasing pedal.
   
5. Repeat Steps 3 and 4 another three times, or
   until sufficient pedal resistance is felt.
   
   WARNING
   Do not let the brake master cylinder fluid get
   below the minimum level during the bleeding
   operation. Keep the master cylinder reservoir
   filled with new DOT-approved brake fluid as
   specified by the original equipment manufacturer.
   Failure to keep the brake reservoir level above
   minimum could result in more air entering
   system, making it impossible to effectively bleed
   the system.
6. Bleed the brake system. Put a wrench on the
   brake actuator bleeder fitting. Start with the
   Passenger Front, then attach a length of clear plastic
   tubing to the bleeder fitting. Make sure the
   tube fits snugly.
   
7. Submerge the tubing in a container of clean
   brake fluid.
   
   NOTE: Both the tubing and container must be
   able to withstand to the effects of brake fluid.
8. Depress the brake pedal 10 to 15 times, using
   the maximum available stroke.
   
9. Loosen the bleeder fitting until the fluid begins
   to flow, (about 3/4 turn), while depressing the
   brake pedal through its maximum available
   stroke.
   
10. Tighten the fitting firmly prior to releasing the
    brake pedal.
    
11. Repeat Steps 6 through 8 several times until
    the discharged fluid is free of air bubbles.
    
12. Repeat Steps 3 through 9 to bleed the
    remaining three brake actuators. Bleed in
    sequence Passenger Front, Driver Front, Passenger Rear, Driver Rear.
    
13. Check the travel of the brake pedal. If a firm
    resistance is felt the manual bleeding
    procedure is complete.
    
14. Check the fluid level in reservoir and fill if
    required. Replace reservoir cap and dispose of
    used brake fluid.
    
15. Remove wheel chocks.

Nanocom Evolution has the following under SLABS / UTILITY / ABS BLEEDING - TESTS:

• POWER BLEED
• MODULATOR BLEED
• FRONT RIGHT TEST
• FRONT LEFT TEST
• REAR RIGHT TEST
• REAR LEFT TEST

Struggling to find any instructions on their usage though.


EDIT: found the following:

Power Bleed.
This function allows to perform bleeding of the main circuit. It activates the pump for a few seconds and you must repeat the function until the oil reaches the brake. The same work can be done by pushing the brake pedal.

Modulator Bleed
Modulator bleed must be preformed with pipes closed, pushing the pedal with maximum strength during the function. Once function is preformed, release the pedal and repeat until the pedal stroke is normal.

So seems like Power Bleed is used on an empty system to get the fluid going through. I assume the pedal doesn't need to be pressed.

Modulator Bleed requires the pedal to be pressed.

But unsure on the tests. Do they need the pedal to be pressed?




EDIT AGAIN:

FRONT RIGHT TEST - FRONT LEFT TEST - REAR RIGHT TEST - REAR LEFT TEST
This function activates the modulation of the brake on the desired wheel. During the function if you turn the wheel by hand, you can see that it is blocked several times for few seconds.

http://cdbl.free.fr/Nanocom/V1-V2/Ma...iscoveryII.pdf

Originally Posted by twr7cx

Struggling to find any instructions on their usage though.

The procedure I posted above is pretty close to what Testbook steps you through as far as I can tell. The best information I'd found was a really sketchy description by a guy who had helped a mechanic do the testbook routine. The WABCO bleed docs seem to match up in general long windedness and the need for repeated bleeding.

The basic approach of modulator bleed with pedal depressed, pedal up for 5 seconds, power bleed, then repeat 3 times will force any air in the system to the calipers. Followed by a manual bleed it should work well enough.

cheers
Paul

I have discovered something strange. There seems to be an almost continuous leak of air through the right front (drivers side) caliper bleed nipple. With the nipple shut and a hose attached full of fluid, are bubble continue to come through (no fluid does though).

I checked the hose fitting and it's tight. Tried it on the other three calipers and they don't do it.

So I removed the bleed nipple and cleaned the seat in the caliper. Refitted and same deal.

Removed a bleed nipple from a 1994 Ford EF Falcon GLi station wagon and fitted this and that stopped the leak.

No air is coming out when bleeding any of the four wheels. Have run the power bleed, modulator bleed and tests using Nanocom Evolution numerous times as per the instructions above.

Strange.