xj40 brakes

Author
Discussion

guru_1071

Original Poster:

2,768 posts

241 months

Sunday 24th April 2005
quotequote all
can anyone help me with the nightmare im having with the brakes on my xj40?

basically (if thats a word that can be used with this car!) the brake pedal is rock hard with the engine off, but as soon as its started (its the early type with the engine driven pump) the pedal will go to the floor and the 'low brake pressure' warning will light up. the previous owner had fitted a brand new fluid servo and the large alloy switch (guess these cost a fair few quid!) but with no joy. i fitted another pump, accumulator, green box and master cylinder from a scrapper but none of this has made any differance.

there is plenty of green fluid in the system, but i just cannot get brakes.

my question is which part is likley to be at fault??. im guessing that the secondhand accumulator i fitted may be faulty as the test suggested in the haynes manual for stored charge doesnt appear to work.

does anybody with more experiance in xj40 brakes than me have a answer (or a second hand accumulator?)

cheers

rich

DrDeAtH

3,618 posts

239 months

Saturday 30th April 2005
quotequote all
do you find that the preesure warning goes away at around 1200rpm?

this points towards the pressure switch unloading the system when the pump isn't flowing enopugh fluid.

look at the switches on the accumulator module, these do leak.

tapping the switches lightly sometimes makes them work........

other than that try looking for a good used accumulator assemmbly, as the switches alone cost £300 from jaguar..

DrDeAtH

3,618 posts

239 months

Sunday 8th May 2005
quotequote all
ok... guy on ebay is selling a vacuum servo conversion for the xj40.....

rather than pay this american for a uk sourced product - (says so in his description)

i'm gonna try and find out which servo it is....
anyone want to join in the quest?