XJS ABS problems

We are seeing a sharp increase in faulty ABS units in the 1988 – 1995 cars. The symptoms are a sharp swerve to left or right upon moderate to hard braking.

While there are other reasons for swerving such as seized brake callipers, faulty brake hoses, poor bleeding etc, we are examining the ABS-related problems here.

The most obvious fault with these systems is that the internal mesh filters (which keep the supply of brake fluid to the solenoid actuators and ‘master cylinder’ clean, become clogged up with a heavy sludge, upsetting the balance of fluid pressure between left and right front brakes.

These filters exist in both the brake pedal unit, and in the pump & solenoid block (identifiable, on the passenger side, by its black pressure reservoir sphere). We have not yet been able to find a satisfactory solvent for this sludge – bearing in mind we have to be careful not to damage the various seals in the units. Even a lengthy soak in an industrial ultrasonic parts cleaner does not always work. So this is work in progress, and in the meantime the solution is to fit a good second hand brake pedal unit or solenoid block.