Hello, I have a 1995 land rover discovery. ive owned it about 6 months now and ever since i got it, we would have a random brake fluid leak. i noticed the o-rings around the master cylinder and reservoir are pretty brittle, but are the problem. it would randomly leak, then be fine for months on end.


last week i totally lost my brakes. after 3-7 pumps, i would have about 20 seconds of "good braking" then all pressure would disappear. i replaced the brake pads, bled about 10 ounces of fluid through through the system, but nothing. we get a nice puddle of fluid near the driver front tire, under the master cylinder and ABS pump, but cannot find a source that is putting that much fluid out. im thinking something is wrong with the master cylinder, but i dont know how to prove it. nothing on this rover is like any other car ive ever worked on.

thoughts?

 

The seals can fail, the master cylinder can fail, if it is the rear master cylinder seal that fails and leaks into the booster, you will also, then need to buy a new booster.
I would suggest you send as much time as necessary to find and repair it before you either cost yourself lots more in repairs or crash your truck.
Either way, do a complete 3 pint flush when done to get rid of all of your acidic brake fluid.

 

Dont mess around with this one, take it to a shop if you cannot find the leak, some things are best left to the pros.

 

Disco Mike is right, chances are it's the master cylinder leaking into the brake booster. This is a leak that can go on for quite some time and never hit the ground. Small amounts can actually be sucked into the engine and burned off with the owner never knowing the better.

Mike is also right about BOTH parts needing replacement if the master is the culprit. The rubber diaphragm and seals in the booster are failed if there is ANY brake fluid in them.

 

^ive had experiences with brake booster leaks. you can tell when you have one when you make a hard turn. (honda were right turns) the fluid in the booster would move to the vacuum line and then burn in the engine.

"my exhaust smokes when i make a right turn" or something along those lines.


and i found out what was going on. there was air in the ABS pump. got it out, brakes actually work!

 

Thank you for posting the fix.
So bleeding the brakes did the job.