1988/89 XJ40.
Would anyone know how to un-screw the black sphere (hydraulic pressure accumulator, item 1 in the illustration) from the silver block that carries it (valve block, item 2 in the illustration)? The black sphere is smooth, and even with valve block nicely gripped in a vise, there is nothing on the sphere to grip on to unscrew it… Very frustrating and puzzling.
Some of the spheres have a recessed hex in the end opposite the threaded part that will acceot an Allen ( hex) wrench but if not a strap wrench like one of these:
will do the trick.
The rubber strap wrench that Mike mentioned may work. However, if your car is like mine, it was screwed on much too tight to remove with that type of strap wrench. Option B is to use a metal strap wrench for an oil filter. Make sure its a sturdy one. Mine bent the handle pretty severely trying to break the sphere loose so I ended up returning it as defective once I finished the job.
Try gripping the sphere in the vise and wrench on the block?
I wrapped mine in masking tape then used an oil filter removal tool. It was the type that has a linked chain similar to a gear chain and has a 1/2" socket drive, the harder you turn it the tighter it grips. It was far too tight for my ratchet and I had to use a 2ft long arm but it came off eventually.
Good luck.
These are pretty great for jobs like this, also very handy in the kitchen for opening up the spaghetti sauce.
I also like spaghetti.
Thanks guys for all the suggestions!
Of course, neither of the two pressure accumulators I have is equipped with the Allen wrench port on the back… It’s beyond my comprehension why is not there a recesses slot for a regular size 15-or-so wrench at the neck of the sphere…
I really liked the strap wrench idea, but afraid this sphere to block is too tight for that tool. I do own a toothed gripping wrench as abercanadian suggested, so I tried that, but unsuccessfully - the wrench is way too weak a design, and the plates on the hook part just bent, as much as I was trying to keep the pressure on the handle straight… The sphere just got paint scratched, too, but would not budge. I’m thinking I’ll get myself tomorrow a chain type one per Casso’s suggestion, and give that undo another try.
Don’t be too concerned about the absence of Allen key holes in the sphere. I can assure you that those they thoughtfully included in the Teves accumulator spheres are useless - the Allen key merely gouges out the metal so you need to revert to a good strap/chain wrench to loosen the blighters!
Would using a heat gun work , not a torch . Or would that destroy the diaphram inside.?
Doubtful that the heat would get too much with a heat gun but if the sphere is to be replaced what’s the harm, apart from boiling brake fluid???
I guess the big takeaway from all this discussion is to make sure the tool you use is a very rugged and stout one. If the tool can hold up to the torque without breaking, the sphere will pop loose.
Well!!!
I have never done such a thing!
…this century.
To be clear, I had no intention of returning it when I bought it. I would have kept it if it weren’t built so poorly with cheap metal.
I succeeded!
The switches and non-return valve off, aluminum valve block firmly in the vise, I used the steel-band oil filter wrench like @wylde8 mentioned. As you can see in the photo, with enough hand force, the handle just buckled. After weeks of contemplating, I went in again yesterday, but this time with a hammer, too. About 10 solid fast “please” hits with the hammer, right at the base of the band-wrench handle, got the accumulator to turn!. I had two of those , so I repeated the method with the other, with the same success 
