I wonder if anyone can help please? My XJS 3.6 petrol couple manual ABS is a relatively new project I have taken on and is certainly throwing out some challenges! The latest was when out for a short drive, I experienced complete brake failure. There was no warning, no hint of what happened. The pedal went straight to the floor and stayed there. It did not return. I managed to get it to a stop and limped home with it, only to find when I got home (5 minutes), the brakes were working again. There were no obvious fluid leaks or any thing else which might throw some light on the matter.
Might this be an ABS issue? If so, why would it self correct? Or for that matter, fail the first place!
I have not actually changed the brake fluid since acquiring the car so maybe that is what the problem is. Althoug for the life of me, I cant see why that wouod gie an intermittent fault.
All suggestons gratefuly received
Thanks
From cold and foggy France
Jeff

 

Typically the scenario you describe is a defective master cylinder that is leaking internally.

 

We need Orangeblossom and PJTS1 on this. I am not quite sure this ABS system actually had a master cylinder in the normal sense.
Greg

 

Hi Jeff

Does your Master Cylinder look like this?



Teves ABS Master Cylinder/Actuator

If so the Symptoms you describe where the Pedal goes right down to the Floor and then recovers later as if nothing had happened, are 'Symptomatic' of Water being absorbed into the Brake Fluid.


Which more often than not is a result of not Changing the Brake Fluid on a regular basis, as unlike fresh Brake Fluid, the water molecules in the old Brake Fluid can Compress, especially with a build up of heat from the Calipers.


Which can cause the type of Brake Failure that you have experienced.


So before we dig any deeper into what else may be wrong, job number one is to change all of the Brake Fluid and then re-bleed the System.


That could well be all you need to do but don't let the Reservoir run out of Fluid or you will have to also Bleed the Low Pressure side of the System, which comes with its own set of 'Gremlins' that you want to try and avoid.


There is a very special way to Bleed the Teves System, so by all means get back if you don't know what that is.

 

Thanks for the reply yes its the same system as the picture so i will change the fluid, dot 4 is i think what is recomended and if you could advise the way to bleed the system it would be great thanks.
Jeff

 

Hi Jeff

Yes!

DOT4 is the Stuff that you need and every time I've Bled my Brakes, I've got through about 5L

Before you Start, one or two things to remember:

(1) Make sure that your Car is Blocked up Safely and can't fall, as your best mate will be underneath and you may need his help in the future.

(2) DO NOT START THE CAR! (Again for reasons of Safety)

(3) Ignition ON does NOT mean start the Car

(4) Keep an eye on the Reservoir Level, Keep it Topped up and don't let it run out of Fluid, as otherwise you will have to Bleed the Low Pressure Side of the System, which comes with its own set of 'Gremlins' you want to avoid.

(5) If you are fitting New Brake Pads, DO NOT LEVER THE CALIPER PISTONS BACK without undoing the Bleed Nipple, as Brake Fluid being forced to go the wrong way up the System can loosen microscopic Particles of Rust inside a Valve and Block it up.

Which can not only wreck the workings of the ABS (of which there are no spare parts) but can also result in having the Steering Wheel suddenly snatched from your hand without any warning.

As your Car takes a dive to the left or the right and if all of your Nine Lives have gone and run out, will then proceed to Spin you off the road.

Been there and done that a couple of times and if that should ever happen to you release the Brakes immediately and then put the Brakes back on as gently as you can, as any problems like that seem to occur with 'sudden braking' like in an Emergency Stop type situation.

(6) Pay very careful attention to the Timing of how long the Brake Pump is running, each time that you Pressurize the System as you do NOT want to Overheat the Brake Pump, as if that happens then it could burn out and they are very expensive to replace.

So where the procedure calls for 15 seconds with the Key Turned on, if you find that's not enough then let the Pump rest for a couple of minutes before you do it again.

There are perhaps unusually Two Systems working in Tandem, where the rear Brakes are Powered by the Pump while the Front Brakes operate in the Conventional Way.

So the Back Brakes and the Front Brakes have their own Bespoke Procedure to Bleed them.

This is a built in Safety Device, as if you find your ABS malfunctions, the Front Brakes should continue to work enough to Stop you safely, assuming of course you're not gunning her round a corner in the wet.

Malfunctioning does NOT include one of the Valves blocking up, in which case you are going to need your driving skill to save you from a potential disaster, as can also happen with a Sticking Caliper.

All Credit for Showing me how to do this must go to Paul (PTJS) who has helped me do stuff more times than I can remember.

So if you do it the way he showed me then you shouldn't have any problems.

This is Paul's Brilliant description of the way its done,

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.

 

HI
Thank you very much for your great answer.
I was wondering if however I can re visit Point 5.
I didnt actually change the pads as they seemed to be in good order but I did however, move the calipers a very very small amount. This was to free them as the car had been standing for around 10 years and they were stuck.
Do you think this might have brought on the problem with the valve block area?
Even though the movement was really really small?
Much appreciate your time in answering and I think I have at least 8 lives remaining! )
Jeff

 

Hi Jeff

You've got 8 lives left?

You better make that 7!

As it looks like a Sticking Caliper may well be the cause of your problem and in fact I would go as far as to say I'm 99.9% sure that this is the cause of your problem.

When a Car has been standing that long then the Caliper Pistons can get a bit Corroded or develop rust and it doesn't take much to have a Caliper Sticking.

This is exactly what happened to my own 'Car Cherry Blossom' where I thought I'd managed to free them off, only to find that they soon got stuck again.

The only other thing it could be is a Sticking Brake Pad or maybe even both.

Either one is going to cause the Old Brake Fluid to boil, especially if it has absorbed some Water.

At which point your Pedal goes right down to the Floor, as you suddenly find the Brakes aren't Working! then when it cools down the Brakes

come back again until the next time, which of course could also be the last time. (Where do we send the Flowers?)

So First things first: Do the Brake Pads slide in and out nice and easy, without the need to tap them with a FBH and Chisel?

They may have done when they were New but do they do that now?

My Brake Pads were in so tight, it took me a couple of hours to get them out, with the aforesaid FBH and Chisel as already mentioned.

This Can even happen with New Brake Pads, as there may be a Slight Variance with different Manufacturers.

So what I always tend to do, if I feel them catching when I pull them in or out, is to grind a little bit off the Top and Bottom edge so that they don't.

That 'May' solve your problem but as for me I didn't really want to roll the dice and have my Grasping Relatives inheriting too early.

So I decided to renew the lot.

New Calipers and New Brake Pads, which were sanded Top and Bottom just to make sure that they slid in easy, together with a New Fitting Kit just for a 'Belt and Braces' approach to be sure.

And of course replaced all the Brake Fluid.

You can get a Caliper Repair Kit but I went the Full nine yards and Treated myself to some New Ones, I really dislike my Relatives that much!



It took me a couple of hours to get this Brake Pad out, with a FBH and a Chisel.




When I fitted New Brake Pads, I skimmed a bit off the Top and Bottom edge by using a Sander, so they Slid in really nice and easy.
Don't let Brake Cleaner anywhere near the Calipers as there's a chance it 'could' affect the Rubber.




New Calipers/New Brake Pads/New Brake Pad Fitting Kit/New Hoses.

As for giving 'The Kiss of Death' to your Master Cylinder/Actuator, you probably got away with it this time.


A Complete run down of what I did and how I did it can be found here:


https://www.jaguarforums.com/forum/x...122634/page13/

 

OK when i was checking for oil spill from the calipers the near side front did smell as they have been binding, did take the wheel off yesterday to check that the bleed screw would undo which it did and the wheel turned with abit of friction but they were cold.
The valve block.....do the solenoids only operate when its necassary to to stop wheels locking?
Thanks Jeff

 

Hi Jeff

The only person that I know who can answer that question is Paul (PTJS) so hopefully he will slide by and give you the answer.

But if you can Smell burning, then you had a lucky escape as my Car nearly turned into a Fireball, when my Brake Fluid boiled and I lost all my Brakes.

This was on another XJS I had that had only been Standing for a Couple of years.

A sticking Caliper and or Sticking Brake Pads are something that needs sorting out before you drive the Car, or it can bite you on the backside when you least expect it.

Oh and if you drive an XJS you should carry a Fire Extinguisher (Preferably Two!)

 

In principle, ABS systems work as follows:
The castellated ring on the stub axle is read by the sensor, and this sends a signal to the ABS system. When the system detects too much of a difference between the rotational speeds of the wheels, it automatically releases some of the line pressure in the slower wheel so as to even up the rotational speeds. This is what the solenoids do. This prevents a wheel locking, prevents the car pulling unevenly, and also gives the shortest stopping distance physically possible. PROVIDING the system is functioning as it should.
On an XJS or any other car the ABS system was NOT designed to work faultlessly for 30 years with no maintenance. FWIW, my view is that any car with an ABS system that has had nothing done to it for 10 years, let alone 25, should have that system completely rebuilt with new seals, electronic connectors checked etc etc. In fact exactly what OB so brilliantly and bravely did for his own car - having had a really frightening experience. A gipsy's kiss for everyone else. And for the lucky people like me with pre-ABS brakes, ditto changing the master cylinder and renewing the calipers/seals.
Greg

 

Hi Greg

If you remember I was very reluctant to shell out 'Big Bucks' for a New Set of Calipers, Brake Pads, Brake Pipes and Hoses.

Right up until the moment that you mentioned 'The Gypsy's Warning' which suddenly brought it home to me that my life was worth a little bit more than a couple of hundred pounds.

I've had Brake Failure Four Times now in one form or another, from having the Pedal go down to the Floor or the Wheel Snatched out of my hand without any warning.

But the one thing that I have learned from Grant and Yourself, is that it is no good trying to cut corners in the hope of a 'Quick Fix' You have to do it once and do it right.

 

Now I have problems, After bleeding the newly fitted front calipers, the brake pedal felt good. The pedal now has no resistance and drops to the floor. The brake fluid came back into the resevoir when the brake pressure motor started.
I have clearly done something wrong. Does anyone have any ideas? I could not start bleeding from the rear as I couod not move the nipples

 

Hi Jeff

It's absolutely essential that you bleed the Rear Brakes first or you will get nowhere anytime soon.

There are no short cuts and no quick fixes, you will have to undo those rear bleed Nipples no matter what.

I had the same trouble trying to undo them on the rears of my Red XJS

The very first thing that I would try is a 1/4 drive Socket and if the corners have got rounded on the bleed nipple, it may need a little tap with a small hammer to get it on.

Or you may have to make a Spanner to fit out of one that's a bit too small, and then give that spanner a little Tap to shock the Bleed Nipple undone.

But NOT too hard, so that you break it off, you will just have to feel your way and use common sense on that one.

If that doesn't work, then try a pair of long nose locking Pliers, again with just a 'little tap' so that you can shock them undone.

But again use common sense on how hard to tap them and not break them off.

Worst Case Scenario, you may even have to drop the rear cage (but hopefully not)

You'll just have to keep at it until you have got BOTH of those rear bleed nipples undone.

Undoing only One of them won't be any good.

And then either get New Bleed Nipples or use the Best ones out of the ones you took off.

Use some copper grease on the threads when you put them back.

Also don't do them up 'stupid tight' or you 'could' have the same problem at sometime in the future.

As for the Valves in the Valve Block, I think you got away with it this time.

But just to show how close you came to not dodging that Bullet, have a look at these photos.

The Rust on the Valves is the result of not Changing Brake Fluid on a Regular Basis and that Tiny Microscopic hole, that you can hardly see is the one that Can get Blocked up.

If you send Contaminated Brake Fluid, the wrong way up the System by levering back the Calipers.

 

You have to bleed the rears, otherwise, instead of braking, you are just compressing air in the brake lines. If the nipples are corroded in, then you have to remove the calipers and change them. I am not saying this is your only problem, but if there is air in the system after the caliper change, then not bleeding the rears is at least part of your problem.
Greg

 

Hi Greg I feel as if we stopped when the pedal felt firm and not carry on to get the air out, but you think it would happen anyway because i need to start at the rear calipers.
I used locktite 638 on the stub axle and this seemed to have removed all the play altough not driven the car to test it properly

 

Still struggling with these brakes.
trying to seperate the caliper from the parking brake in order to remove the caliper, have removed the 2 7/16 bolts and spring clip is there anything else I should be doing as the two dont seem to be wanting to seperate!
Thanks in advance as always

 

That should do it, if you mean the two long chromed bolts the HB calipers swivel on that go into the caliper each side. Is the axle out of the car? If not, it is miles easier if it is. Why are you removing the caliper, is it shot?
Greg

 

Sorted it gave it a tap with the hammer, doing it with the axle still in the car. The bleed nipple broke off while trying to undo it and the other side is just as bad but have'nt broke it yet, your right it would be easier if its all out of the car

 

Hi Gregg
to change the rear hub pivot bearings do i need to undo the drive shaft or is there enough movement when i remove the large pivot bolt