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I have a 1990 XJS with ABS. I’ve removed the brake actuation unit, checked all solenoids, cleaned and inspected the o-rings/cups inside the master cylinder. It was dirty but all the o-rings/cups were soft and looked new. I reassembled the brake unit and installed it back into the car. When I went to bleed the brakes the brake pedal goes to the floor and is stuck there solid on the floor. Putting 12v to the 3rd or 4th ABS pin OR opening the bleeder on either rear caliper will allow the brake pedal to come off the floor. I’m pretty lost at this point
First of all, I assume that you bled the low-pressure side of the system before you bled the wheel circuits? You absolutely have to do that if you've removed the actuation unit.
The other suggestion is to bleed the rear wheel circuits as per the Teves-defined procedure, rather than the Jaguar-defined procedure. The Teves procedure is as follows:
BLEEDING TEVES BRAKES
TWO PEOPLE REQUIRED
START AT REAR LEFT, THEN REAR RIGHT (UNLESS JUST ONE REAR BRAKE NIPPLE) THEN FRONT LEFT, FRONT RIGHT.
ONE PERSON IN THE CAR, ENSURE BRAKE FLUID LEVEL IS FULLY TOPPED UP.
TURN ON IGNITION AND WAIT UNTIL BOTH ABS AND LOW PRESSURE LIGHTS HAVE EXTINGUISHED AND ALSO THE MOTOR PUMP HAS CUT OUT.
THEN, OPEN REAR LEFT BLEED NIPPLE AND HOLD BRAKE PEDAL DOWN, WITH IGNITION ON FOR 15 SECONDS – NO MORE
TIGHTEN BLEED NIPPLE, TURN OFF IGNITION, RELEASE BRAKE PEDAL.
WAIT ONE MINUTE AND REPEAT FROM RESTORING SYSTEM PRESSURE AS ABOVE FOR OTHER NIPPLE IF FITTED – THEN WAIT ONE MINUTE AT LEAST BEFORE MOVING TO FRONT BRAKES – THIS PREVENTS THE MOTOR PUMP FROM OVERHEATING.
AT THE FRONT, ENSURE SYSTEM PRESSURE IS CREATED AND THEN BLEED CALIPERS CONVENTIONALLY WITH IGNITION ON, USING SLOW STROKES AND GO THE FULL TRAVEL BUT DO NOT FORCE.
ONCE THE LEFT SIDE HAS BEEN DONE, AGAIN WAIT ONE MINUTE AND THEN RESTORE SYSTEM PRESSURE.
ENSURE BRAKE FLUID LEVEL IS CHECKED AND TOPPED UP AFTER EACH CALIPER IS BLED.
Was there something wrong with the Brakes that made you do that?
Or did the Brakes go wrong because you did that?
Either way you've almost certainly now got Air in the System that needs to be Bled Out
Starting with the Low Pressure Side of the System, where you should follow the Hard Line from the Reservoir to the Brake Pump on the other side of the Car, where the Brake Fluid enters the Brake Pump through a Plastic Elbow that's held in place with a Pin that you have to Pull out as this Pin Secures the Plastic Elbow in the Pump
Basically what you have to do is fill the Reservoir up with Brake Fluid and then Pull the Pin out of the Plastic Elbow and then Pull the Plastic Elbow out of the Brake Pump, so that the Brake Fluid runs Free and only when the Brake Fluid runs Clear without any Air Bubbles do you put the Plastic Elbow back in the Brake Pump
In other words you do this 'On the Fly'
(1) Plastic Elbow out
(2) Brake Fluid Runs out polluted with Air Bubbles
(3) When Brake Fluid Runs Clear Put the Plastic Elbow Back in the Brake Pump and then replace the Pin
Obviously this is going to make a bit of a mess with Brake Fluid running free everywhere
SO DON'T LET ANY BRAKE FLUID GET ON THE PAINT OR IT WILL STRIP IT WHILE YOU WATCH
So Pack Old Rags everywhere round the Brake Pump and cover all the Paintwork with Old Towels and have a Bucket of Soapy Water Standing by to sluice down any spills and you could even make a Tin Foil Channel to divert any Brake Fluid into a Container under the Car
If anything goes wrong at this Stage you can always put your finger over the End of the Elbow to Stop the Flow of Brake Fluid if things get out of control but don't worry too much, as this is the Low Pressure Side where Brake Fluid Flows to the Brake Pump under Gravity
If all this sounds too easy then it isn't exactly the 'Walk In The Park' that you would want it to be, as that Plastic Elbow will need some firm but gentle twisting and turning and pulling to get it out of the Brake Pump
WHATEVER YOU DO DON'T BREAK THAT PLASTIC ELBOW or that will spoil your day and you may have a problem finding another one So do be watchful of that
Hopefully you won't have any problems and if you're very Careful you may not even make a mess but just be aware that can happen
Here is my Thread complete with all the Photos you will need to do the Job though if it sounds over dramatic, take into account it was written a long time ago, though by the time I'd done this job my nerves were completely frazzled
Then after you have done that Bleed the Brakes in the Way described by Paul (ptjs)
I purchased the car with no brakes. They would pump up but quickly go to the floor. I replaced the accumulator and still had no brakes. So I moved onto cleaning up the brake actuation unit. I bled the low pressure side by letting the pump run for no longer than 45sec at a time and put a hose into a cup on the high pressure line and did that until no bubbles and clear fluid came out.
As of now the only way to bleed the brakes is to put 12v to one of the abs solenoid, have a partner pump the brakes until hard, then I can take the power off the solenoid and bleed one wheel. If I don’t have 12v on that solenoid the pedal goes to the floor in one push and is stuck to the floor. You couldn’t pull it up if you tried. The rear brakes are engaged but for some reason aren’t allowing the fluid to return?
That is not the right way to bleed the Low Pressure Side
This has to be done under Gravity with the Ignition OFF as having the Brake Pump running will completely defeat the object of the exercise and could in fact make things worse, so bleed the Low Pressure Side again as has been described and then Bleed the Brakes in the way described by Paul (ptjs)
As mentioned, you must bleed the LP side first, the correct way, before the HP wheel circuits.
And secondly, Greg's suggestion about a collapsed flexi is really good. And that's why releasing the abs valve electrically to allow fluid return back from the valve block to the reservoir could be allowing the pedal to return back up.
I’ll definitely look into a possibly collapsed rubber brake hose! I’ve had that happen to plenty of brakes hoses before.. I guess this Jaguar is just intimidating to me.
I’ve already bled the brakes 5 times. So I don’t know how I’d still have air in the low pressure side..
I also don’t understand how unhooking the high pressure line from the master cylinder and turning the key on to pump fluid into a cup wouldn’t bleed the low pressure side.
I’m also going to try the correct way of bleeding the low pressure side, it doesn’t make a bit of sense to me, but it’s easy and I can rule that out.
Hahaha. The XJS, like the cats they are, will sense your nervousness and hesitation and POUNCE...lol... Brother, there is nothing to be nervous about. After all the mystique, rumors, legends and etc,,, they are just cars afterall. Most things are yes, a little different, but not that much.
The gravity fed feed,,,, It's a long horizontal tube that runs across the back engine bay, near the fire wall, to the pump alllllll the way on the other side of the engine bay... If there is air, an air jam, in this line (it's only a fill line as fed by the weight of the fluid in the reservoir, gravity and FULL-NESS) the pump will run but never be actually pumping fluid into the rear braking system... ALL the air needs to be run out of that line. You need to detach that line from the pump assembly (CAREFULLY) removing the pin and wriggling the elbow out of the cast (take your time hear or no fun), and placing the end in a bottle/container. If you can apply a little positive pressure to the reservoir opening it will help. Push the air bubbles out and reset the elbow and the pin while running full stream. Check the ORing for wear/tear...
I'm not sure why you undertook the job you described in your first post. But, if it was because you were having braking problems, got ya. In that, there is a regulator valve (I think it's called a proportion valve) that lives just UNDER the reservoir and ABS assembly. You'll find it in the hard line equal level with where the downpipes connect with the exhaust manifold. It's not a fancy looking thing, just a largish hex shaped knuckle. Brake line in and out in both ends to rear. It regulates and balances the brake fluid pressure, distributing just a LITTLE less pressure to the rear brakes than the front. Prevents the brakes in the (lighter) rear end from locking up on hard braking at speed.
I had a problem with mine and they do rust internally and clog. Or, degree can clog them. Mine was leaking and there is no fix. I deleted mine.
Then, as Greg suggested, the rear soft line just over the LH cage area. Not hard to replace.
Then you can bleed them thangs. Easier said than done.
Gravity Bleeding the Low Pressure Side of the System, is basically Priming the Brake Pump with Pure (Air Free) Brake Fluid
Doing this is vitally important
As if not the Brake Pump cannot deliver Air Free Brake Fluid to all of the Brake Lines when you Bleed them one at a time by using the method described by Paul (ptjs)
As Jay and OB have said, the LP side is critical. The complexity of the Teves is because it effectively runs two inter-connected systems. The fluid reservoir sits on top of the actuation and directly feeds it, but it also has a separate fluid feed to the pump via that cross pipe If you don't bleed that first, the pump circuit can (and does) air-block. You can bleed the high-pressure wheel circuits all day but you'll never sort the problem. The pipe removal technique as described by OB is the only way and is as described in the Jaguar workshop manual.
Okay everyone thanks for the advice!
I’ve bled 1/2 quart into a container off the LP elbow and got absolutely 0 bubbles.
Replaced the rear rubber brake line
brake pedal stuck on the floor with one single press.
this makes it impossible to do any type of bleeding procedure.
Hahaha. The XJS, like the cats they are, will sense your nervousness and hesitation and POUNCE...lol... Brother, there is nothing to be nervous about. After all the mystique, rumors, legends and etc,,, they are just cars afterall. Most things are yes, a little different, but not that much.
The gravity fed feed,,,, It's a long horizontal tube that runs across the back engine bay, near the fire wall, to the pump alllllll the way on the other side of the engine bay... If there is air, an air jam, in this line (it's only a fill line as fed by the weight of the fluid in the reservoir, gravity and FULL-NESS) the pump will run but never be actually pumping fluid into the rear braking system... ALL the air needs to be run out of that line. You need to detach that line from the pump assembly (CAREFULLY) removing the pin and wriggling the elbow out of the cast (take your time hear or no fun), and placing the end in a bottle/container. If you can apply a little positive pressure to the reservoir opening it will help. Push the air bubbles out and reset the elbow and the pin while running full stream. Check the ORing for wear/tear...
I'm not sure why you undertook the job you described in your first post. But, if it was because you were having braking problems, got ya. In that, there is a regulator valve (I think it's called a proportion valve) that lives just UNDER the reservoir and ABS assembly. You'll find it in the hard line equal level with where the downpipes connect with the exhaust manifold. It's not a fancy looking thing, just a largish hex shaped knuckle. Brake line in and out in both ends to rear. It regulates and balances the brake fluid pressure, distributing just a LITTLE less pressure to the rear brakes than the front. Prevents the brakes in the (lighter) rear end from locking up on hard braking at speed.
I had a problem with mine and they do rust internally and clog. Or, degree can clog them. Mine was leaking and there is no fix. I deleted mine.
Then, as Greg suggested, the rear soft line just over the LH cage area. Not hard to replace.
Then you can bleed them thangs. Easier said than done.
Alright, the proportioning valve didn’t solve my issue.
I’ve found that the pedal only sticks to the floor if the brake pump/accumulator has pressure on it.
this makes it impossible to bleed the brakes in the rear because if the pump turns on the pedal goes soft and goes to the floor becoming stuck.
I get in the car press the pedal once.(it’s now stuck)
Release rear brake line at the ABS block
pedal returns to normal position.
If I do that ^ 4 or 5 times the pedal gets hard and no longer sticks on the floor.
Turn on the ignition and it’ll stick all over again
I just feel like there is a massive amount of air in the master cylinder/actuator unit.
What is the procedure to bleed the master cylinder and abs block?
I'm going to try and find an exploded view of the master and it's inner workings... Are there rubber bits inside of the master that can be changed out? I can't look now, but will...
For lack of a better description at the top of the hinged peddle must be some kind of rod that goes into the master transferring the pressure you are applying to the peddle to the inner workings of the master.
Has it ever worked correctly?
And, what if you manually reach down in the EARLY phase of the bleeding and pull the peddle back up by hand when it sticks to the floor, pull it back up by hand and then pump it that way?
Although it's possible, I've never heard of an actuator failing in a Teves XjS or getting an airlock or needing rebuilding at all. The valve blocks do have problems but your pedal problem seems to be a different issue. There is no defined procedure specifically bleed the actuator or valve block. I've not heard of anyone ever needing to do it.
You seem to be building pressure in the rear circuits that doesn't get released when the pedal pressure is not applied. Your method of opening the rear abs valve to release the pressure seems to confirm that.
That seems to imply a pressure lock in the pumped rear circuit. As you've eliminated it being in the online pressure valve, I would now look at the rear flexi as internly collapsing.
Thank you guys so much, everything helps. I just keep checking things that it could possibly be off the list.
Rear rubber brake line is brand new, didn’t solve the problem
I’ve cracked every line loose for the rear brakes.
(cracked loose to release pressure/bled)
Every single one including all the distribution blocks
I’m thinking my actuator unit is no good. I’ve suspected it since I got the car but 800 for a used one or 1600 for a new one doesn’t sound fun at all
04-21-2021 | 03:37 PM
Brake pedal stuck to the floor!
