Hi All,I have a 1968 Jaguar 420 and my break stopped working.It was on a long drive, banging up the toll motor way at 80mph and i used the breaks and nothing worked, but on the second or third depression they were fine, and for the rest of the trip no problem.I parked her up on the drive way for a week or so before I could look at her, by this point the breaks had totally stopped working, when I looked at the two break tanks seemed low so I topped them up no difference.The tanks have stayed full no change at all, I've pumped the breaks endlessly, no affect, I can not see any obvious leaks (and the tanks are still full).Now I'm just starting out and learning so this maybe well be past what I can do,but any pointers and ideas will be greatfuly receivedThank you

 

My first thought is that the master cylinder is failing. It could be letting fluid past the seals instead of pushing it to the wheel cylinders. But I'm not sure.

If you have a 420, as opposed to a 420G, you want this section of the forum: https://www.jaguarforums.com/forum/m...40-daimler-61/

 

If the pedal initially went to the floor and gradually moved up as you pumped the brakes, that is a sure sign of brake fluid getting past the lip seals in the master cylinder. Parts may be a bit difficult to find, but there are specialist firms that will rebuild your original part. White Post Restorations is one such firm.

 

Hi Alistair,
Welcome! I want a LHD 420 with a 4 spd OD in the worst way. I think they are great looking cars.
As far as your brakes go, there are only 2 places for the brake fluid to go if you don't see it on the ground. The first is the interior. Check around the carpet up against the dash panel around the brake pedal and below the brake pedal. You may have to pull the carpet away from the sheet metal because it may drip behind it. The second is the brake booster. if the internal seal between the vacuum reservoir and hydraulics fails the brake fluid could end up being pulled into the engine and burned. Personally I would start with the master cylinder.

I hope this helps