Hello, once again I check in with the Jaguar tech gooroos on the forum to ask for some help!

I've noticed a failure in the braking system of my 1991 4.0 Sovereign. The red brake warning light comes on after some intensive braking (from +-80km/h to standstill for example). It only stays on for a few seconds before it switches off again. It's on just long enough to be able to check the VCM, which reads 'FLUID'. (Fluid level in the reservoir reads just below max, sometimes it's higher, sometimes it's lower)
I searched the fora for help and found out it might be the accumulator that is going bad with age. People have described a way to check for possible failure by counting the amount of times you can press the brake pedal before you 'hit a brick wall'.
So I did some investigation:
I left the car parked for a day or two, switched on the ignition into auxiliary and heard the electric pump build up pressure. I then removed the key and tried to count how many times I could fully push the brake pedal before I hit the 'brick wall'. I read 20-30 pushes means the accumulator is going bad and 40 pushes is good.​​​​​The 'brick wall', when the brake pedal fully stops, is there at the second push, but I can still push the pedal down quite far. The 'brick wall' continuously gets closer to the resting point of the pedal, but after 40 pushes I can still push the pedal in, but only for a few centimetres.
I then tried the following: keep the key in auxiliary and push the pedal and I found out the electric pump switches on after EVERY deep push on the pedal.
Can anyone confirm or deny that this is the accumulator going bad? Not very keen on buying one (€450 new!) and finding out my original one is still good.

Secondly, the unit that contains the accumulator, pressure switch and electric pump has a little play in it. When the pump switches on (and off) the entire unit shakes 0,5cm back and forth. You can also easily shake the accumulator-unit by hand.
Is this normal?

Thank you for the help!

 

I had the red brake light and the yellow ABS light on in my 92 but the car stopped fine. I bled the old fluid from the brakes and all is well although there was no leak or lack of fluid in the system so no other repair was done. Maybe try this first since you seem to have a fair amount on accumulator reserve. As far as the unit being loose, just replace the grommets at the units' mount bolts if they seem bad or are missing. Good luck!

 

Hi Douwe,

It does sound as though your accumulator is not storing sufficient hydraulic pressure. The electric pump should not run so often. Search these fora for references to a General Motors / AC Delco accumulator that may fit your car at a much lower cost than the Ate or Jaguar/Land Rover-branded units.

As Jerry mentioned, you can probably replace the vibration-isolating grommets for your pump/valve/accumulator assembly. You may find some generic windshield wiper mounting grommets at a local auto parts store that will fit. The original parts are no longer available from Jaguar.

Cheers,

Don

 

Thank you for the tips! I'll try and look into replacing those grommets, didn't know they also functioned as an vibration-isolator.
Funnily enough (and quite possibly just one of those classic Jaguar things) the red brake light hasn't come on in a long time, braking is fine again and nothing shakes anymore. I've pumped the brakes hard on an empty road, coming to a full stop from +-60km/h a few times and everything seems to work fine again.
I guess if it works it works, but I'll definitely keep a close eye on it.

 

Ha! Easiest first, right? (even if you don't realize you're doing it) Thanks for letting us know.