Hi Guys

Had a bit of a disaster after the MOT Test, as I think the Tester may have ruptured the Seal between the Accumulator Black Ball and the Brake Pump by applying too much pressure to the Pedal

Which resulted in a noise like a Rocket taking off when I got home and Brake Fluid even Squirting out of the Front Grill in the form of a Mist!

Still not sure what happened only guessing at the moment, so as a bit of a double check

Please could someone tell me if there is supposed to be an 'O' ring or some sort of Seal between the Black Ball and the Brake Pump, or a Copper Washer, or maybe nothing at all?

 

OB - you poor *******... I feel for you.
Mind you we are watching the World One day Cricket comp...(every 4yrs for our USA friends) and our winter has been better than your summer.!
Sooo many games rained out!

Can't help you with your brakes... my advice is buy a warm rug and snuggle in and watch the English play... (they will be beaten by the Black Caps (NZ).
Back to your brakes... from a selfish point of view I look forward to your repair as I know if will be well documented if and when it happens to me I will know what to do!

Look forward to the update!
As only Grant could say, open your cupboard and have a warm beer... YES the Pom's drink warm beer!
Been there and given one... from a cupboard! LOL

 

Hi Duke

Cheers!

But everything always seems to happen to me!

So often that it's nothing more than really just another day at the Office, so one way or another I will sort it out

People with Normal Modern Cars just don't know the Fun that they are missing, or maybe they do!

 

There should be a black O ring between the pressure bulb and the pump. Of course it should be brake fluid resistant. Jaguar doesn't sell them separately...

 

Hi Daim

Cheers!

Haven't had a chance to look at it yet but as well as the 'O' ring, if its got one, what are your thoughts on using PTFE Tape on the rest of the threads?

 

As long as the o ring sits right and is compressed, no problems. Though it is rare for the accumulator to pop. Have you checked the pressure hose from pump to actuator? They do like to go brittle and people like to ignore them...

 

Hi Daim

Brake Fluid was Squirting out from around the underside of the Ball, so maybe the Sealing ring was broken by the MOT Tester pushing the Pedal much harder than it needed to be

And then it may have started to unscrew itself?

Only guessing at this Stage, as its chucking it down with rain outside and haven't had a chance to see what went wrong

 

The ball is charged with nitrogen to about 3,000 psi, so pushing on the pedal won't do anything to the seal. There is a very specific procedure to remove the ball, you need to depressurize the system first, so read the instruction before trying to remove it. I can't remember them all off the top of my head, so don't want to give you bad advice. It's different from most other braking systems, so read up on it first.

The system needs to be able to withstand a panic stop, so the amount of pressure you could put on the pedal is within the design parameters. If that blew a seal, it needed to be replaced. Last time I checked those ***** were NLA. Some BMW's use a similar system, but the threads are different. I believe they are the same as some late 80's early 90's US model Fords (Thunderbird/Cougar I think)

 

Hi Jagboi

Cheers!

I will see what I can find out but I'm not a big Fan of ABS and seriously considering Retro Fitting a Brake Booster, one of the problems being that I haven't got a Spare Vacuum outlet on the Inlet Manifold

Though no doubt there may be a way

 

Hi Ob,

My parts catalogue lists part number for item 3 in Daim's post is JLM 1477.

Seems to be expensive as part of a seal kit for the accumulator. SNG Barratt seem to show the most comprehensive pics of what the kit comprises and competitively priced. Suggest you have a look if not seen already.

You may also find specialist seal manufacturers who can supply the individual seals themselves.

Cheers,
LeeP

 

Hi Lee

It may have an 'O' ring on already but I haven't had much of a chance to check it out yet

Very Strange as I have not heard of anything like this happening before

 

Is there any chance the MOT inspector put all his weight on the ball when leaning into the engine? I have never heard of this happening. You did not change this recently yourself, obviously?

 

Hi Spike

Yes! I did change the 'Ball' some time back and tightened it up with a wrench and since having done so it has been working perfect without any problems and the correct amount of Brake Travel

But all that changed after the MOT where there are On-Screen Instructions for the Tester to follow, one of which is to 'Brake Hard' so no idea what happened, except to subscribe to the Theory that he may have really leaned into it as you say

Because the braking system never felt the same after that Test, so no idea what happened as your guess is the same as mine

 

I mean, your options are limited at this point, as far as guessing what happened.

Could be that you did something incorrectly or used a bad part or bad o ring when you installed it and this is just an unhappy coincidence, or perhaps the mot inspector leaned his weight into the accumulator, as I said...

It could even be, that for some reason, nefarious or not, he decided to unscrew it ..... you never know!!- there was a member a few years back that posted how he took his XJ-S to a high end detailer to get the car washed, and the imbeciles working there could not figure out how to open the bonnet, and they proceeded to use a crow-bar and ruined the bonnet and the paint!!-YES, THAT DID HAPPEN.

At this point I would want to take the car to a specialist to figure out the problem. A specialist who sees XJ-S’s all the time. This actually behooves us all at this point!

 

OB,

If I remember correctly, when you changed the sphere, didn't you use a similar, but not original one?

Is it possible that your replacement sphere used a slightly different type of thread that you were able to tighten into place with a (Uk-type) wrench but which actually ripped a new thread that wasnt really sealing? And then the MoT was just the coincidental day that the damaged thread just failed?

Just a thought...

Paul

 

You wouldn't get very far, it's impossible to move if the system has not been depressurized. You have to pump the brake pedal about 30 times ( seriously) with the ignition off to depressurize the system.

 

There is actually a company in my area that sells these accumulators, of various sizes and specs, I also have a spare here you could borrow if you reaaalllllyyy needed to. But really the black ball is just a car-adapted part that is well in use in many industrial applications, and if you know what 'category' of supplier to look into you'll find some company with a suitable part, there was also a guy on here who used a Merc ball it was slightly less capacity but it worked.

 

Hi Paul

I swapped it out for an Original XJS 5.3 Ball and it also screwed in perfectly as you would expect, so I cannot see that as the problem, as the Braking System was working A1 before the MOT

 

Hi Spike

While going to a Specialist sounds a very Tempting Idea!

I'd rather spend that money on another Ball, as since the Brake Pump is working and I have rebuilt the ABS and replaced all the Brake Lines and fitted her with New Calipers

The Ball is highly likely to be the only thing left that it could be and in any event I don't trust Shops so would rather fix her myself

 

Hi VancouverXJS

That was a very kind offer which was much appreciated but I'm starting to think that something happened to the Ball, when She was given a Brake Test on the Rolling Road

The whole of the Braking System has either been rebuilt or replaced by myself and so by process of elimination, the Ball is the only thing left that it could be

Something Weird must have happened during the Rolling Road Brake Test