Colin,
I would say its time to go through the brake system…
Remove the front wheels, the calipers, and remove the pistons.
You need to remove the rubber boots, then maybe twist and pull the
pistons out.
You may find them rusted and in very poor shape.
Then you have to inspect the calliper bores. If they look ok,
order new pistons and all rubber bits and new guide pins, and do things
up right.
You may also have a master cylinder problem, but they can be rebuilt…
they sell kits for them.
No way I would pay for a new or rebuilt one, they are not complex.
Just make sure you don’t get any brake fluid on any paint.
Before doing all that though, I would go over all the callipers,
and bleed the system well.
If you open the bleed screw and push down the brake pedal, fluid
and/or air should come out…make sure all the air is out.
Air in the brake system does odd things…will make brakes bind when
hot, yet have soft/no pedal when hot or cold…
Inspect the brake pads…surely the one that has been binding will
be worn much more than the others.
If all the pads are worn, in could be air in the system, or a problem
with the master cylinder not letting the pressure vent into the tank
when your foot is off the brakes…this is often an adjustment or
dirt problem, or sticking parts.
No way to tell without going through the system…but don’t throw parts
at it, as its expensive to do it that way…better to spend the money
on what the car needs, then on guesswork…
Brett
1990 XJ6
…Date: Mon, 05 Jul 1999 22:17:28 +0100
From: Colin Drysdale colin.drysdale@virgin.net
Subject: [modern] No brake function
Sender: owner-modern@jag-lovers.org
To: modern@jag-lovers.org
Hi folks,
My 1987 XJ6 2.9 (no ABS) has developed a problem with its brake system.
It started with the brakes binding on when encountering heavy traffic,
so I suspected a sticking caliper. I decided to take one pad off the
caliper and use the pedal to push the piston out and lubricate it.
Problem No. 1 was that even with the pedal to the floor, the piston
would not extend. I reassembled the calliper assembly.
Problem No. 2 then reared its head. Now the brake pedal can be pushed
forward with no resistance - and no brake function whatsoever! The
pedal and brakes had previously operated normally.
I took the car to the local garage who suspects either the hydraulic
pump or the master cylinder but, unsure of which is at fault, he
recommends taking it to the dealer.
But wouldn’t failure of the hydraulic pump cause the opposite effect.
i.e. the brake pedal would be difficult to operate due to no pressure
being available for the servo assist?
Could the problem be a stuck piston or perished seal in the Master
Cylinder?
On an aside, how does the accumulator fit into the big picture? It has
a pipe going to the servo, a pipe going to the equaliser valve(??) and
a hose going to a device on the front of the engine, next to the
radiator fan.
Any advice/ideas would be greatly appreciated - I hate not knowing
whats going on…
Best Wishes,
Colin.
87 XJ6 94,000mls.