I'm a Jaguar newbie and just bought a 1993 XJS six cylinder automatic with 93k miles that was well maintained (at least up to approx 60k miles (which occurred in 2003) for which I have the complete records). After 60k miles the record is very spotty. It is in nice shape and has been garaged.

The reason the owners sold it was that it had a problem and they had "too many cars anyway" so they sold this one.

The problem is that when you take the car out for a drive, everything is fine at first. After a mile or so, you can hear at least one brake pad rubbing against the rotor as if the piston is not fully retracting. A mile or so later the brakes locked up on their own (except for when stopping at a stop sign, the brake pedal is not touched).

The owners had previously brought the Jag to the local Jag dealer and were told that, the rear brakes are locking up, that the 'computer' is bad, and to get ready to shell out serious money. So they decided to sell instead. They had owned the car for 3 years and drove it 3,000 miles during that time period.

My brother in law, who has had Jags for many years, told me to call his mechanic.

The mechanic, who is a Jaguar specialist said that it is probably a relatively easy fix and that it could be something as simple as the handbrake not being released properly. The emergency brake pads, if rubbing against the rotor would get progressively hotter and eventually lock up the rotor. He gave me a step by step instruction on how to properly pull up and lower the handbrake and said that could possibly solve the problem.

Another possibility could be that one of the brake lines was 'hit' and severely pinched. This would result in the brake pads engaging when the brake pedal is depressed...but when the brake pedal is released the brake fluid retracts very slowly due to the pinched line and again the dragging pads would heat up and lock up the brakes.

I still have the XJS at the previous owner's home and need to get a truck and car trailer to pick it up XJS. But if possible, I would prefer to trouble shoot it in their driveway and fix it there if a simple fix. They live approximately 70 miles from my house.

Any other ideas as to why the breaks are progressively tightening and locking themselves up?

Also, I hope I posted this question in the appropriate forum

Thank you very much.

 

Sorry for the long post and I hope it is understandable. FYI, I did an intensive search on the internet on this issue, but found almost nothing helpful.

 

There is a chance that the flexible line or lines to the rear axle cage and from the cage to the rear calipers are going home. What can happen is that the flexible starts to perish inside, and it gradually closes up and while the force of the brake pedal will allow fluid to the callipers, it cannot come back easily enough to release them.

I amnot saying it is this, but it is certainly worth changing them and seeing it it makes a difference. If it does not, then the ABS system most probably is quietly pressurising the rear brake circuit on its own.

Greg

 

Thank you Greg.

On another website I found the following as a TSB for the XJS:

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"Check rear braks TSB"

"ISSUE
Premature rear brake pad wear (in less than 3000 miles) is due to the brake pedal sticking and applying continuous low pressure to the rear calipers. Brake pedal sticking can be caused by over-tightening the pivot bolt or incorrect setting of the brake light switch.
ACTION
Use the procedure below to correct the problem.
SERVICE PROCEDURE
Loosen the nut for the brake pedal pivot bolt 1/2 turn.
Re-set the brake light switch as follows: Loosen the switch and adjust switch position so that when the plunger is fully pressed in, there is at least.025 ° clearance between the plunger and brake pedal.
Inspect the rear discs for excessive wear and calipers for possible heat damage. Replace components if necessary.
SYSTEM OPERATION
The initial movement of the brake pedal (3/16" travel) applies 2 bar (29 psi) pressure to the rear brakes only.
The pressure delay valve (located on the L/H inner fender on 89-91 MY vehicles and on the R/H inner fender on 92 MY vehicles) then holds this pressure until the front brake line pressure has reached 8 bar (116 psi).
When the front brake line pressure reaches 8 bar with continued load on the brake pedal, the pressure delay valve opens and increasing pressure is then applied to both front and rear brakes."

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Does anyone think that this may be another possibility in my effort to try and identify the problem?

I want to gather as many possible fixes as I can before making the long drive to try and trouble shoot the issue.

Thanks again

 

That TSB seems to highlight exactly what you are experiencing. Do the fix the TSB outlines, buy some flexibles and see.

Ensure you know how to bleed the brakes before you go though. There is a specific way you must belled the barkes on these systems. Sorry I do not know what it is.

greg

 

Thanks for all the help. Unfortunately I have to move the car from the previous owner's residence and the person with the trailer that was going to tow it away for me backed out today. I can't really deal with it so decided to list it on Craigslist. Hopefully a Jag enthusiast will buy it. It really is a nice car.

Take care

 

Sad you had to sell, now I have this problem after fixing up the master cylinder.

I do remember extending the pivot pin inside the master cylinder to hopefully take up the slack in the peddle which was not necessary as I reconditioned it already. My brakes where smoking.

I will back it off and see how it goes and then change out the lines.

Good luck everyone!!