Brake bleeding and advise.

[ecosselynx]

Hi

Getting pulled out of my comfort zone (Mk2) but looking for a bit of help for a friend (club member, but not to hot on the key board).

Anyway at the back end of last year he stripped his front hub to replace his disc's and hub bearings/seals, due to various family reasons he never got back to it until March.
He's got everything re-built OK and bled system.
Bleeding was a bit slow but fluid came out of tank filler cap a few times but assumed I had overfilled then I pushed on pedal to check still hard and fluid peed out of filler cap. OK when he switched on pump. This morning when he went to check - fluid was higher in tank and overflowed during night.
When he pushed on pedal which went to the floor and fluid pi**ed out like a fountain from the filler cap. When he switch on ignition the fluid pump works and stops as it should, and ABS light goes out.

So something appears to being bye-passed to the tank side of the system and forcing fluid
back to the tank and reducing/leaking pressure in line. He cant see any exterior
leaks anywhere.

If anyone has had a similar experience could they please post a reply. I hoping to be able to travel at the end of the week where we can have a go at fixing the issue, so any and all advise welcomed.

[PaulGover]

Had a very similar experience after replacing my front subframe. I found the Teves ABS, which I assume this is, a right b*gg*r to bleed. My problem turned out to be air in the back brakes, even though I don't recall touching them while the front was apart.

What I found was the cure was to bleed the back brakes as per the workshop manual, several times. It took several litres of fluid, so buy a gallon from Halfords or whoever.

I remember that at first you couldn't follow the manual precisely - something like depressing the pedal to the floor before turning the ignition, but the pedal wouldn't move until after - or maybe you were supposed to discharge the accumulator by repeatedly pressing the pedal, and then push to the floor, and at first you had to leave the accumulator charged - I forget which.

As an aside, my fluid reservoir on top of the master cylinder had collected a fair amount of crud; I bought a new one (there's no way to disassemble it to clean the interior), but it was seriously expensive. I guess over the years previous owners had neglected to flush the system regularly, again taking care to follow the manual.

[ptjs1]

John,

Hi, you haven't mentioned the year of the XJS but I'm guessing it's an ABS-equipped car with the early (Teves-type) ABS that uses integral master cylinder/valve block arrangement.

As Paul G has mentioned, you have to bleed the brakes on these cars as per the complex workshop manual routine which involves discharging the accumulator pressure initially.

As with all XJS owners, I would really advise that your colleague purchases the correct Parts and Service manual on CDRom from Jaguar Heritage. The brake section details the precise bleeding procedure. Just a personal view but I don't think anyone should run an XJS without the official Parts and Service manual. It's so cheap that it's complete false economy not to buy it.

Good luck. Give me a call if you want me to talk you through the bleeding procedures.

Paul

[ecosselynx]

Hi

Thanks for the prompt replies lads. He has a full set of CD's and manuals, so were Ok on that front. Sorry can't remember the age of the car, but it is ABS. I'll need to bone-up a bit on all this modern stuff, keep you all posted on how we get on.

thanks again

[boots1234]

1990 3.6 with early Teves ABS after fitting new front hub bearings, discs, caliper seals and pads.

With excellent help and combination of David Marks sending the correct method of bleeding Teves (ABS) brakes and Mk2 Ecosse Lynx doing all the bleeding work while I just sat in the car following instructions the problem has been "sorted".

One possible theory was air in the main valve/master cylinder which prevented valves or something being closed under the pressure of fluid causing a back pressure of sorts for fluid to pee out of the filler cap when pressing the pedal down. Probably leaving the system partially without fluid for a few months did not help.

Whatever, the answer appears to have been using the Teves method of bleeding which is different to the manual method ie basically the former states to have the ignition ON when bleeding the fronts whereas the manual states to switch the ignition OFF when bleeding the fronts. David Marks mentioned that the system must be pressurised correctly for bleeding to be successful.

Teves method of bleeding is set out below

Thanks everyone especially David and Mk2 Lynx - I initially had visions/nightmares of having to buy very expensive spare part.

BLEEDING TEVES BRAKES

TWO PEOPLE REQUIRED
START AT REAR LEFT, THEN REAR RIGHT (UNLESS JUST ONE REAR BRAKE NIPPLE) THEN FRONT LEFT, FRONT RIGHT.
ONE PERSON IN THE CAR, ENSURE BRAKE FLUID LEVEL IS FULLY TOPPED UP.
TURN ON IGNIITON AND WAIT UNTIL BOTH ABS AND LOW PRESSURE LIGHTS HAVE EXTINGUISHED AND ALSO THE MOTOR PUMP HAS CUT OUT.
THEN, OPEN REAR LEFT BLEED NIPPLE AND HOLD BRAKE PEDAL DOWN, WITH IGNITION ON FOR 15 SECONDS – NO MORE
TIGHTEN BLEED NIPPLE, TURN OFF IGNITION, RELEASE BRAKE PEDAL
WAIT ONE MINUTE AND REPEAT FROM RESTORING SYSTEM PRESSURE AS ABOVE FOR OTHER NIPPLE IF FITTED – THEN WAIT ONE MINUTE AT LEAST BEFORE MOVING TO FRONT BRAKES – THIS PREVENTS THE MOTOR PUMP FROM OVERHEATING.

AT THE FRONT, ENSURE SYSTEM PRESURE IS CREATED AND THEN BLEED CALIPERS CONVENTIONALLY WITH IGNITION ON, USING SLOW STROKES AND GO THE FULL TRAVLE BUT DO NOT FORCE.
ONCE THE LEFT SIDE HAS BEEN DONE, AGAIN WAIT ONE MINUTE AND THEN RESTORE SYSTEM PRESSURE.

ENSURE BRAKE FLUID LEVEL IS CHECKED AND TOPPED UP AFTER EACH CALIPER IS BLED.

[ecosselynx]

Hi

Thanks for al the valuable information an suggestion. Managed to get it sorted out, looks like the front system had some air in it which seemed to be in the valve block, preventing the system operating as normal. Anyway a bit of perseverance and we won out, got the air out and all working as should be.

regards