I have located an accumulator for my XJS and understand there may be pressure in the system, so one has to be cautious. Can someone give me the procedure to follow to do it right the first time. There was something about pumping the brake pedal a lot of times, but that may not be an issue with the pedal on the floor. Anyway, help need here and appreciate it very much. thanks ron

If your pedal goes to the floor, you’ve got no (or very little) pressure in the ball

Thanks. Could you fill me in on how to set the system up to accept the new ‘ball’. I heard about the need to pump the pedal a few times…

Nothing special. Unscrew the old one, screw the replacement. Pumping the pedal till hard is only necessary to relieve the pressure so brake fluid does squirt all over the paint (doesn’t apply to you).

There is an oring. Don’t forget it when you put the new accumulator.

The pumping to relieve pressure thing has never worked for me. Be it 20, 30, or 50 times - you will get a spray of brake fluid when you unscrew the accumulator. I just wrap a lot of absorbent towel around the base of the accumulator before removing it.

Thanks for the quick replies and I will go ahead and try it out. I did talk to a shop that does a lot of work on these cars and they advised not to bother with a used unit. They have new ones for around 500 bucks, which seems like an awful lot for a ‘new’ one that may have sat on a shelf for lots of years. And I also learned that other cars use the same model accumulator, and a LOT cheaper. Nothing to lose here. If it works; great. If not; no great loss, just some time to screw the replacement on there. Again, my thanks, and I will post my results in a day or two. ron

Thanks, that is what I needed to know. Pretty simple, and when I pulled the other one off the donor car, it did not have any pressure left, but it had a lot of fluid remaining in it, and I drained that off. I did put a rag over the unit and got it off with little trouble.

Yes, used part is a big NO.
Substitutes for the ridiculously priced Jaguar part can be found here:

And if I may, unsolicited advice - the accumulator ball/sphere is likely the original part and needs to be replaced, but since you have “pedal to the metal” situation with your brakes, IMO, this is not going to be the fix.

Ditto, what Steve said.

I juat ordered an AC Delco 25528382 which cross references with the XJ6 unit. fingers crossed

Well, it can’t hurt to give it a try, and if it TEMPORARILY solves the problem, I will buy a new accumulator to be on the safe side, Just want to try get brakes on this car for now and decide what I am going to do with it. A $500 car, is a $500 car, and if it runs, it may worth a lot more with brakes. The engine sounds sweet and not even 60000 on the car.

Is that the version that is slightly larger than the Jag OEM sphere (but will still fit into the available space)? :confused:

Well, I now have two accumulators! Both build pressure so what now? I am thinking master cylinder, as pedal goes to floor and no leaks underneath. In one of the threads, someone mentioned that the car would work, even without the abs working, and still another chap offered the idea of replacing the system with the older vacuum booster. I looked, and there does not seem to be much room where the existing setup goes. Again, any and all advice appreciated. I want to drive the car to see if I like it. With only 56,000 miles, that engine is smooth as glass. thanks ron

Shut off all electricity to the ABS system and the front brakes should work. You’d have to push hard on the pedal to stop the car, but the pedal should be hard. Yank some fuses, tell us what happens.

Thanks. I was over there today on the accumulators and pumped and pumped, and it takes some effort, but it still goes to the floor, and I am thinking master cylinder failure. I never liked this system, and got all kinds of mixed messages on the brakes. I tried the pedal with the car running and car off, and no difference. When running and pumping the brakes, there is a light on the dash that looks just like the accumulator image with a cross across it, as if to tell you that is the problem. What next?

As to retro-fitting the vacuum booster and ordinary twin master, I am wondering if there is enough room for the booster setup and saw one conversion on a RHD car, and it fits, but mine is a LHD model. The booster itself is reasonable in price and most any master would work, providing the mounting holes line up with those on the booster. I know the front brakes have separate lines, but a ‘t’ fitting would take care of that. Let me know your thoughts on this, and thanks

This almost sounds like you are describing the “Bulb Failure” indicator light - could possibly be indicating that you have a failed bulb in the brake light section - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 7/30/2020 0005hrs. EDT USA,

Probably not. With the vacuum booster and the master cylinder in place, the forward end of the master cylinder sits just below the diagonal brace. I dare say most generic master cylinders – which typically have a built-in reservoir – will interfere with the diagonal brace. That’s probably why Jaguar went with a remote reservoir.

Retrofitting the earlier non-ABS vacuum boosted power brakes in place of the Teves III should be fairly straightforward utilizing the Jaguar master cylinder, a Mitsubishi reservoir, and a GM vacuum booster. The hard part is that the job absolutely requires the pedal box from a pre-ABS XJ-S; the pedal box from an XJ saloon won’t do.

As I responded to your PM - you need to make sure the supply line is belt properly and the pump is running.
The Teves III ABS system is one of the most frequently discussed topics, as the understanding of what it does and how it is operating is not good. Here is some relevant information:

In short, if you CONFIRM that the front brakes are free of air and there no leaks - engine and ignition off - brakes should operate as conventional brakes and can be bled as such - then the problem is in the solenoid block/master cylinder.

In theory, conversion to an old-school vacuum boost should be fairly straightforward, but there are many details that need to be worked out and some of the brake lines need to be reconfigured.

I don’t recall what the situation with the proportioning valve for the rear brakes was (it is also frequently discussed here).

Paging @BobPhx
He did the conversion (couple to a modification from auto to 5-speed manual) and documented the experience here: