My XJ-S is 24 yrs old , @ some point the ABS master cyl will need attention. As of today no one that I know sells a rebuilt or kit for it. So, my choices : change it over to non ABS vacuum boost @ a reasonable price, or buy a new one "$3000" . Any ideas ?
Lawrence

 

Hi Lawrence

The only real option, is to Fix it yourself.

Its not a very difficult job, just a bit of a PIA, assuming if it does go wrong you are still alive to tell the tale!

I've had the Brakes go wrong on Four XJS's

(1) Grey XJS Coupe - Brake Fluid Boiled - Lost all the Brakes.

(2) Grey XJS Convertible - Brake Fluid Boiled - Lost all the Brakes.

(3) Blue XJS Convertible - ABS Valve Block Failed - Nearly Spun me off the Road.

(4) Grey XJS Convertible - ABS Valve Block Wire Broke (Inside The Valve Block) - Nearly Spun me off the Road.

Its really got me thinking about a Fiat 500 how about you
Anyway here's how to fix it:

https://www.jaguarforums.com/forum/x...photos-140828/

 

Your right it's very easy to rebuild "if" the master cyl is no pitted "and" you can get hold of a rebuilding kit, which I'm not aware of Co. that makes one. Of course some people go for the used ones. In any case your dealing with 20 year master cyl.
Lawrence

 

As far as I know a New Valve Block is no longer available, I tried to buy one myself, if it was is would be in the region of £300 (UK)

Ditto with the Master Cylinder/Actuator also no longer available £1,500 (UK)

That's the same price I paid for a Merc in Pristine Condition!

Wheel her into a Garage/Shop and they would be wanting 'Megabucks' to sort her out for you.

 

After reading these threads, I'm feeling very thankful I have a MY 1995!

Is the 1995.25 ABS system really that much more reliable than earlier models? How is it different? I'm assuming it is less prone to total brake failure, yes? Reading these stories about total brake failure is kind of freaking me out. :-/

 

XJDanny,

The 1995.25 system is really quite different, although it does have the same principle of a 6-solenoid valve block.

The 1995.25 uses a relatively conventional tandem master cylinder with a typical brake servo bolted to it. One chamber provides fluid to the front brakes. One chamber provides fluid to the rear brakes. Brake bleeding for both front and rear is undertaken via a conventional bleeding routine using brake pedal pressure.

The earlier system does not have a conventional "master cylinder" (despite what some people say). It uses an actuator unit with an actuator piston and a boost piston. The very front chamber of the actuator unit functions as a small master cylinder providing the output of fluid to the front calipers under non-ABS conditions. The rear brakes are not fed with fluid under foot pressure but with pumped fluid via the pump and accumulator. That is why the procedure for bleeding the brakes is quite different with the rear brakes not being bled via the use of the brake pedal.

The ABS valve block for the 1995.25 MY system is integral with a pump and two small accumulators, which is quite different from the earlier system. the valves function in the same manner as the earlier system using a Normally-Open Inlet Valves and Normally-Closed Outlet Valves. They also use a ribbon cable connection to fire them.

Why does the later system appear to be more reliable? I'm not sure if it is really. It's true that it doesn't use a complex actuation unit with the actuating and boost pistons, but I've not heard of many owners experiencing problems with that. It's also true that it doesn't use the large sphere-type accumulator which can be a cause of problems after some years. But the major cause of "one-sided brake failure" seems to be inconsistent application of the solenoid valves which are also used in the 1995.25 MY. My wild guess of the apparent more frequent failure in the older cars is:

- The earlier system is using an electric pump to boost the fluid during normal application. In addition all the rear fluid is pump driven. This may(?) cause an increased movement of sediment in the solenoid valves compared to the later cars.

- All the earlier system cars are older! So there's a greater likelihood of poor maintenance, sediment build-up, and deterioration of the ribbon cable etc. I have a 1994.75 MY car, the last of the older system and I've not had a problem (yet!).

As I suggest to everyone, read through the manual and understand how the system works You'll see the fundamental differences between the 2 systems. Then change your fluid regularly and always open the caliper bleed valves when retracting the caliper pistons.

Hope that helps

Paul

 

Hi Danny

There is not much more that I can add to what Paul has already said as well as the way he has explained it.

I have had Three of these units apart and what you see inside these can be the stuff of nightmares, as the ones I took apart had badly corroded Valves with Fragile Ribbon Connectors that can break.

As it is so easy to do a Test with a Meter, with the Unit still in the Car.

I am now so Paranoid, that I check the Oil and Water and do the Test with the Meter, every time that I go out.

In the event that a Test with the Meter Fails, all the Re-Wiring in the World isn't going to fix it.

It could be a Wire, it could be a Valve or a Combination of Both, in which case all you can do is take it apart, assuming of course you are going to try and fix it yourself.

The downside being that New Valves are NLA as are the repair kits.

At least I have not been able to find any for Sale.

The result of this is that I can say as a 'Die Hard' (pun intended!) XJS enthusiast, I just don't enjoy driving my Car/s anymore, as I know what can happen and I have had it happen one too many times.

You want to drive it in the way in which it was intended, not like some mad 'boy racer' but in keeping with the conditions and restrictions of the road.

And not have your heart in your mouth every time you go out, just in case something happens and they decide not to work.

I haven't been out for a drive for days, as its really shaken me up.

Although the Brakes are working fine at the moment, I simply do not trust them.

Overtake someone at 70mph Touch the Brakes and if they fail, then it could be game over.

I just don't want to drive her anymore and instead have been concentrating on restoring my other Car.

I think its down to the Age of these Cars, coupled to poor maintenance and above all renewing the Brake Pads, with the Bleed Nipples still closed, forcing debris back up the pipes and Blocking up these Valves.

Give me the Old Fashioned Brake Booster System, on any day of the Week, then at least I know that the Car is going to Stop and in the event that it doesn't, then it must be down to me.

 

OB,

I felt quite sad reading your post about how you don't feel confident driving the car. I absolutely understand why your incidents will have shaken your confidence. I know this may not be of much comfort but I'd leave you with these thoughts:

- As ABS-equipped owners, we've all got a potential problem The only difference is that the rest of us drive around with false sense of confidence because we haven't experienced the scary problem yet.

- Because you've worked on your ABS block, cleaned it etc, your car should now be much less prone than any one else's to experiencing the problem again. We can tell from your posts and pics that you've been thorough and comprehensive in the approach that you've taken.

So, if you can use logic rather than emotion (easy for me to say, I know!) you should believe that your XJS is much safer than ours in experiencing brake failure again. Your ABS block has been refurbished, you have new calipers & pads, some new brake pipes and you have clean fluid throughout the system. So, all the elements of a safe functioning brake system.

I know it may take a number of successful safe journeys before the thought of problems has gone completely to the back of your mind. But it will. In the same way that none of us consciously think any more about all the scary tyre blow-outs, stuck accelerator cables, shattered windscreens and rear-endings that we've all had throughout our motoring lives.

Weather's looking good for the back end of next week. So how about a top-down run to the coast, fish and chips on the beach and then regale us with a great tale of XJS cruising next Friday?

Cheers

Paul

 

Hi Paul

Fish and Chips on the Beach. Mmmm!

I used to do that all the time, the GF and myself are addicted to Picnics but no words can describe the feeling of what happened to me.

Its not like Classic Brake failure, where you start thinking, 'Hello' somethings wrong with the Brakes, so I think that I'll change down a gear and that Grass Verge is looking Ok, I'll pull off the road just there.

And do you know what, I might even use the hand brake.

Its about as far away from that as you can get, as more often than not with the ABS only One wheel is affected.

So just imagine standing still and then right out of nowhere someone barges you in the side and tries to knock you over.

Its much more like that, because the whole weight of the Car (about Two Tonnes) is thrown on One Wheel, with not the slightest warning, that its about to happen.

After all you've been driving for Miles, at all sorts of Speeds and the Brakes feel fine, because in normal driving you brake gently and progressively.

As driving in that manner doesn't engage the ABS.

The Problem only arises when it does.

Maybe on a Corner or a Roundabout, or even pulling out to overtake.

As long as you don't touch the Brakes and not going too fast you will be fine.

But if you suddenly put on the Brakes and a Valve in the ABS is slow to react, then there is a very good chance the Car will suddenly try and dive to the other side of the Road which can literally happen in a 'Blink'

As all of the Weight of the Car goes on One Wheel.

I've overhauled the System in the most meticulous way but the one thing that you cannot do is see inside those Valves.

You can only do your best and who knows that might not be good enough.

So give me Six of those Brand New Valves and then I'll have no doubt that She'll be good to go for many years, as otherwise its like playing 'Russian Roulette' with five shots in the Gun.

Although I'm sure you'll be Ok, you've got a different system in your Car.

Just ask yourself why they decided to fit that.

 

Paul and OB,

Thank you for the replies and helpful information. I greatly appreciate your feedback.

I was hoping for better news but from what I'm reading, my MY 1995.25 has the same solenoid valves as the earlier cars therefore the same potential for one-sided brake failure. Ugh...

My ABS light comes on from time-to-time and then goes out when I restart the car. I don't know what this means. My brakes seem just fine. Other than the light coming on, the only other problem I've had with my brakes is a pull to the left, which I had repaired with new calipers and pads. But I'm feeling insecure now. I almost wish I hadn't read this post as ignorance can be bliss. ��

Danny

 

Hi Danny

While I don't know anything about the System in your Car, as I have the earlier set up.

If the ABS light comes on, it 'could' be a potential problem in the making and if it decides to malfunction, ignorance may not be bliss anymore.