Its been a couple months since I drove my 94 xjs. Its been in the driveway while I have been sanding it for new paint.

I started it it up to take it for a drive around the block, pulled out of my driveway and hit the brake pedal which went all the way to the floor. I pumped the pedal about fifty times really fast as I coasted and eventually had to hit the e brake to stop.

Slowly backed it back to the driveway. Checked the brake fluid and it was full. Tried pumping the brakes and the pedal will harden for a second as I get the acuumulator noise and then the pedal goes right to the floor. When I purchased the car ( a couple years ago) I had an issue where I had to pump the brakes a few times to stop and replacing the accumulator ball fixed it. The accumulator is only a year old. Even if it was bad I do not think I would loose all my braking power. ?

As far as my knowledge goes, if the pump was bad I would just have to press really hard to get it to stop. What would cause no brakes whatsoever?! I was always under the impression that brakes were pretty fail safe in that they are designed to not completely go out. This could have been much worse than it was. Makes me kind of want to rip the whole braking system out and go with something safer. Im pretty sure I have the teves mark 2 system.

Any thoughts?

 

I think the solenoids stick, and allow the fluid to pass back into the reservoir, bypassing the brakes altogether. From what I understand, if you pull the fuses going to the ABS, brakes will return. From there, its most likely you need to completely flush, renew fluid, check operation of the solenoids. Just read a good article on here, withing a thread on the exact same topic. I am a new owner of a 89 with Teeves III, although not new to Jag ownership at all. I think your car has what is called Teeves IV isn't it? BTW, the accumulator is most likely still good, as I think they last 10 years or more before losing their pressure. When bad, the pump just has to run more, but as long as the pump is working, the brakes will work fine. As a matter of fact, with the fuses pulled, the brakes will work, even though you may lose rear brakes, due to the pump not running. I'm not fully up on it yet, but am feeling that I'm getting a decent grip as to what makes these systems work.

 

I think you are right about the solenoids sticking. I dont read too much about the master cylinders going bad. I just flushed the whole system out a year ago. The fluid is crystal clear. This should not have happened. Scary. I doubt paint dust caused it from sanding the car, though its possible if its not sealed very well. It has been slowly losing fluid since I have owned it and I cant find out where. At least its not at the calipers.

I am going to focus on the actuator unit. I already have new calipers since the front one is sticking. Its time for a complete tear down and rebuild of the entire braking system. Cant chance driving up the winding roads along the CA coast with unreliable brakes. The parts for the newer system seem much cheaper.

It would be good to know if anyone has upgraded the system to the 96 xjs version and what that entails.

 

Its been a while but I will update this. I did a SECOND flush of the system. Pulled the actuator apart and removed the circtuit board, resoldering all the wires. ...I have very good soldering skills (it was my job at one point). Replaced all the brake hoses and the brakes have been reliable ever since.

I still get fear at times thinking they could go out at any point (which is why I am always looking for upgrade parts to the 95 or 96) but so far no signs of failure.

It was sitting in the driveway for about six months when I had that failure. I am guessing the solenoids were stuck. the brake fluid is crystal clear and has been since I owned the car. However, there was some neglect at one point.

so good for now on the brakes. be careful if you do not drive you car a lot. if it sits you could experience brake failure.

 

note: this is the teves system without the vacuum booster. nothing to worry about with the booster system.

 

If you were losing Brake Fluid, the chances are that Air got into the System, hence a reason for your Total Brake Failure, with the pedal going right down to the floor and multiple pumping making no difference at all.

As if the Actuator (Black Ball) goes, then you should still have braking on the Front Wheels.

The fact that its all working now, seems to point to that.

 

You are correct the Teves M2 was used up to 1995.

The system is failsafe so a complete failure of the ABS system and pump will not produce the symptom of the pedal going to the floor.

I'd also go with the AIR in the system. If I were you I'd bleed the system. Here is a link on how bled mine.

Jaguar XJS Restoration : How to bleed Jaguar XJS teves ABS

 

there was a slight hose leak. the odd thing was the reservoir was full at the time. its still a bit baffling to me.

 

It is possible for a small leak to happen from one of the wheel hoses without the reservoir immediately dropping. This is because the system valves are precluding fluid from moving from the reservoir at various points in the cycle.

Paul

 

If Fluid gets out, then Air can get in and you may be surprised how little you need for the Pedal to go to the Floor.

Its certainly not unusual to get through 5 litres of Brake Fluid, while bleeding out all the Air.

And certainly not unusual to have to bleed the Brakes twice, before you end up with the really hard pedal you need.

 

I think I bled them about 4 times... they work great now!

 

I was thinking all of us had come to the conclusion that sticking solenoids in the abs control unit was the culprit of total loss of brakes. If it did it once, it will doing it again. Unless you correct what caused it to begin with.

QUOTE=hoodun;1321024]I think I bled them about 4 times... they work great now![/QUOTE]

 

Everytime I read if brake failures in our cars it makes me feel we are all driving time-bombs

 

hoodun,

Well done! Glad you were able to get them sorted!

I think it's reasonable to say that if you understand the system fully, then COMPLETE loss of brakes is very unlikely to be the fault of faulted or jammed solenoid valves. A failed solenoid valve is more likely to induce the symptom of the car diving to one side under moderate to heavy braking as the jammed solenoid effectively gives rise to the loss of braking on one front wheel and the car dives to the other side.

I think that our awareness of the problems is at least making owners consider a more disciplined approach to fluid replacement, the absence of which I suspect is the prime cause of solenoid jams.

Paul

 

Even after reading this entire thread, I still cannot say that the brake loss situation with my '94 AJ6 is an exact match to any of the individual brake loss entries here.

To start the car I need to depress the brake pedal for my start/stop engine push button to work, so I can always tell before starting the engine whether I do have a brake loss situation or not. If I start the car the day after I've had it running (or even two to three days after) I do not experience any brake abnormalities, but if I let at least four days or more go by without driving it I begin to notice that the pedal goes down low, even to the floor with enough days gone by. Reservoir? Absolutely no loss; the level won't move from full and there are no signs of a leak, anywhere.

However, all I have to do is to pump the brakes a few times and the system returns to 100% normal, meaning it's even possible to lock the brakes and to skid the tires if forced to do so. Then, if I continue to drive the brakes continue to behave totally normal for as long as I want to drive it.

Then, I do need to let a few days go by for the brake pedal to go low again.

Problem is that, based on this behavior, I can't understand what is exactly causing it:
1. There is no fluid leak to the outside, no signs, including a full reservoir.
2. There's no air in the system because once the long travel is removed by pumping it, the brake pedal feels firm and never spongy at all.
3. If there was an internal (cup) leak I'm sure that I would gradually lose braking power when I go out for a drive and use the brakes often.

What can be causing the pedal to drop and then go back like if nothing's wrong after pumping it a few times? BTW, this has been happening for at least six months by now. It's just that I don't drive this car much and I haven't been able to do car shows either (spine surgery problems), so the car tends to just sit there and so do the brakes.

Technical minds hate to "fix" a problem by doing whatever without ever finding out what was the actual cause for this to happen in the first place, (such as replacing the master cylinder without being able to "prove it" wrong...).

Any hints?

Thank you,

 

have you replaced the accumulator ball? if so, you appear to have air in the system. these brakes are a paint to bleed. I had to bleed mine several times before I got all the air out. if its filled with fluid and there is no air in the system, there is proper pressure, its never going to require you to pump it to the floor several times. so either you are needing to build pressure do to a failed accu ball or you are compensating for air in the system.

I know about 70% of what Im talking about btw. So hopefully a second opinion will chime in.

 

Folks, check out my blog, link at the bottom, for en easy bleed method for the Teeves.

I disconnected the the reservoir as I totally drained my system, you can skip this step and just bleed at the caliper

 

The brakes on this car were bled by the local dealer a while back when I had the entire fluid replaced. They explained to me that they use a special computerized machine that has the fluid inside and connects to all bleeding ports and ABS system at once. They connect the machine to all four bleeding ports and I forget where else, then they just hit the "start" button and the machine takes over on its own, doing all of the steps for a complete system bleeding and ABS testing in about 20 minutes. Nothing escapes, including ABS issues. I may have this done again, only that I first need to know what's wrong with my system before we bleed. I'm curious as to whether this "wonder machine" goes as far as diagnosing if it is the ball or the master cylinder that needs replacement. Only issue is that dealers are not cheap. BTW, what does the ball do?

Cheers,

 

Forcedair1,

I'm slightly confused by your symptoms. Are you not getting an ABS failure light coming on? If you can lock the brakes and skid the car, then your ABS has been disabled in which case you should at least have an ABS failure light.

My suggestion would be:

- Start a new thread on this to avoid disrupting hoodun's thread and to have a meaningful title etc

- Don't change anything until you've diagnosed the problem logically. These forums are littered with owners who replace one part after another with no understanding of whether they are the cause of the problem.

Good luck

Paul

 

I am at a loss honestly as to what the problem was.

There are six solenoids. This is what I do not fully understand. Could one of those prevent pressure from happening if it was to fail? I figured three go to the wheels and the rest to either the pump, mc, res. ? ? ?