Can anyone tell how to bleed the rear brakes on my 1990 XJ40 please?i have followed what it sys in the manual but it doesnt seem to do anything.

 

There are several threads on this subject. Just search brake bleeding. For these cars it is not really something one person can do, due to the ABS pump.

 

Hi Gerard,

It is possible to bleed the rear brakes by yourself, but easier with a helper. If I recall correctly, on the cars with electric ABS pumps, the one-person procedure goes something like this:

Top up the brake fluid until the level is close to the bottom of the reservoir filler neck
Raise the rear of the vehicle and remove the rear wheels
Install a brake bleeding wrench or box end wrench on the right rear brake caliper bleed screw
Install one end of a clear/transparent tube onto the bleed nipple and direct the other end into a catch bottle (ideally, the tubing should aim upward from the bleed nipple)
With the ignition off, press and release the brake pedal about 20 times or until it becomes firm/hard (this will force the ABS pump to run when the ignition is turned on)
Using a stick, camera tripod, extendable paint roller handle, heavy tool box, etc., prop the brake pedal in the fully-depressed position
Switch on the ignition and quickly move to the right rear caliper
Open the bleed screw for at least 15 seconds to allow a sufficient volume of fluid to flow (the ABS pump should be running)
As soon after 15 seconds as you notice no more air bubbles in the tubing, close and secure the bleed nipple
Remove your prop from the brake pedal
Shut off the ignition
Top up the brake fluid in the reservoir again to just below the filler neck
Move your wrench and bleed tube to the left rear caliper and repeat the above bleeding process
Top up the brake fluid to the MAX line
Carefully test the brakes for proper operation, and if necessary, repeat the above procedure

Cheers,

Don

 

Thank's but for 3.6l is not good no?

 

Thank you Don, I have tried this, I pump the brakes until it goes firm then ask my helper to press the brake peda, (it doesn't go down very far) when i eopen the rear bleed valve nothing comes out. i have removed the bleed nipple and it is clear. I have tried this on both rear wheels and the same thing happens. Am I doing something wrong?

 

No. On the 3.6L the ABS pump is mechanically driven by the engine so the procedure is different.

 

Are you turning the ignition ON at the appropriate time and if so, is your ABS electric pump running? The pump is mounted on the firewall to the right of the engine when viewed from passenger compartment.

 

BLEEDING THE REAR WHEELS
For the AR, the maneuver is completely different.
Start with the wheel ARD, for LHD, ARG for RHD.
The procedure is as follows:
- Press the brake pedal.
- Opening of the bleed screw, the old liquid comes out, the pedal depresses until the stop.
- Keep the pressure on the pedal.
- Switch on the ignition without starting the engine.
At this moment the assistance pump starts and again the old liquid comes out.
When it is clean and bubble-free:
- Close the trap.
- Cut contact.
- Let the pedal go up slowly (3 seconds as usual)
- Fill the jar to the top again


- Go to the other side, to repeat the exact same maneuver.
Finally, make the exact level in the jar.
- Switch on the ignition without starting the engine.
- Wait for the assistance pump to stop and adjust the level.
Do not forget to replace the small protective rubber caps on the bleed screws.
The old brake fluid, like the new one for that matter (but it is more expensive), is an excellent "degreaser-breather".
Spray or (and) pass with a large brush, then rinse with water.

 

I dont think the ABS electric pump is running, i will look into this further. Many thanks all!

 

I have found the relay for the ABS electric pump and if I short it the pump does run and I can bleed the brakes. It obviously runs constantly in this situation. Does this matter or should it stop? What controls the on/off? I have read it is by pressure, but can't find what component I should be testing.

 

Hi Gerard,

The electric pump is switched on and off by the low pressure/warning lamp switch, which is Part 2 in this diagram. It looks like a component from a nuclear submarine and threads into the valve body next to the electric pump motor:



You can test the switch at its terminals (I think I remember that there are 5 terminals) to confirm that the contacts are closing when the system pressure is low.

You can see how the switch is wired in the Electrical Guide, which you can download here:

Jaguar XJ40 Electrical Guide 1990

When the switch failed in our '93 and I could not immediately find an affordable replacement, I ran a pair of wires from the switch harness connector to a momentary push-button switch that I tied to the hand brake handle so whenever the BRAKE warning lamp illuminated I could press the button for several seconds to run the pump to recharge the system and extinguish the warning lamp. Eventually I found a good salvaged complete electric pump/accumulator/switch assembly on eBay. If your switch has failed and you find a replacement, be sure to depressurize the system before you remove the old switch (with the engine off, press and release the brake pedal repeatedly until the pedal goes hard).

When you get a change, please visit your User Control Panel (User CP) and edit your signature to add your Jaguar's year, model and engine details, and perhaps the last six digits of the VIN, so that information will appear in all of your posts and others won't have to scroll all the way back to your first post to be reminded of those details in order to provide accurate replies.

Cheers,

Don

 

Hi guys, for MY 1987 the process it's the same but with the engine run ?