Hi,
Yesterday I took out the old Jag (1995 XJS-6cyl) for a drive. At some point I wanted to make a right turn but when I hit the brakes to slow down there were no brakes.

Later on there were some brakes and then no brakes and then good brakes for the rest of the trip. I made it home safely!

The main hint I can give you is that when there were some brakes the whole front end violently shook only when I hit the brakes. When the brakes were good there was no vibration. While driving no shaking at all.

Another point I should mention is that when I got the car a few years back the brake pedal has always been hard.

Any hints as to what I should be looking at?

Thanks,
Jomo

 

From reading others there seems to be a common complaint of hard brake pedal on a properly functioning system , at least on the 4 door sedan

Even though it is a XJS , the inline 6 engine brake boost vacuum line fitting at the intake manifold is a Squirrelly banjo fitting on the top of the X

The question on the production number of the 1995 XJS is the engine and it's parts for a AJ6 or AJ16

The large brake boost diaphragm can also be leaking

Air in the brake lines ? U shaped bleeder hose ?

Further compressible air in the brake lines allow the caliper piston pads to not be held steadily against the rotor so it sets up a situation of oscillations

 

OK, I am extremely confused. I can't find my brake booster. I looked between the firewall and the master cylinder but do not see what I thought a brake booster would look like. I also looked for a hose from the master cylinder area to the manifold but did not see any. Can I please bother someone for a picture or a diagram of the hose/brake booster.
Thanks,
Jomo

 

It’s a big fat gigantic round black drum.

Maybe it still has the teves electric booster?

 

No big round black drum. That was just what I was looking for.

 

It's confusing because you have posted a question about your XJS in the X300 forum.

I'm not very knowledgeable on the XJS but I know many of them had a pump and accumulator set-up - so no vacuum booster. Best to take your question to the XJS forum.

 

if this is a LHD car look for a black sphere with a big danger sign on the right side of the car close to the firewall. this is the original teves electro-hydraulic pump booster master cylinder combo




this is what an AJ16 XJS should look like, big black drum in the top left corner