Hi all, I,m in Oz so car is RHD. My brakes are now permanantly like pushing a brick. Initially problem was only on start up and brakes would be right after a few minutes but gradually got worse. New pads and front rotors now in. Calipers and guide pins cleaned and lubed. Bled 4 times now. Same problem. So I'm assuming it's an issue with this strange hydraulic boost setup. Any similar experience out there?

 

Hi Andrew,

Welcome to the Jaguar Forums! It's great to have you with us!

The most common cause of the hard brake pedal is failure of the hydraulic brake fluid pressure accumulator. The accumulator is a metal sphere approximately four inches/100mm in diameter. Inside is a diaphragm that separates two hemispheres. In one half is pressurized Nitrogen gas. Hydraulic fluid is pumped into the other half and presses against the diaphragm, compressing the Nitrogen and allowing hydraulic fluid to be stored under pressure, something around 1,200 psi if I recall correctly. This provides a reserve for power brake assisted stops even if the engine dies.

In an '89 model your accumulator is probably in the right front area of your engine bay and possibly accessed by removing or displacing the wheel arch liner, though on your RHD car it may be that your accumulator is on the left side - I'm not certain.

I am attaching the service manual which contains procedures for diagnosing malfunctions. Please keep us informed.

Cheers,

Don

 

Hi Andy: Your car is equipped with the Mark II Teves ABS system from W. Germany. It is comprised of several component pieces such as the accumulator that Don had mentioned and a master cylinder/booster assembly and the pressure switch being the main parts. My used to own an '88 Olds Toronado that was equipped with the same ABS unit and I encountered the exact same issue. If memory serves me, I had to replace the brake pressure switch. It was a simple task.I would recommend purchasing a service manual in either the hard copy or cd version. ebay is a good source for either. Welcome and good luck with your issue. Ren

 

Thanks gents. Now to find the time to work on it.