The brakes on my 2000 LS400 work fine, however; if pressure is kept on the brake pedal, it gradually goes down. There are no external leaks at the wheel cylinders or the master cylinder. I am assuming that it is an internal leak in the master cylinder which will get worse with use and time. Is there a good source for the procedure to replace the master cylinder and to bleed the system? From what I have found so far, other systems must be bled also.
Thanks in advance.
E.J.

 

Is the level falling in the brake fluid reservoir?

 

might just needs to be rebuilt.