The brake fluid reservoir level drops very fast in my 2007 4WD V6 Toyota Tacoma, probably within 3-5 days of filling it up. The funny thing is, it drops to just below where it says minimum but not further down, which makes me exclude the possibility of brake lines leaking somewhere downstream in the system and suspect that the problem is that the reservoir itself has a leak very near the top which causes this initial level drop. The brakes work fine but this causes the brake light to be on all the time.
I was wondering if replacing the reservoir will involve draining and bleeding out the whole system. Or can I just pump some out the top to below where the reservoir is mounted, replace and refill it?
EDIT: I noticed that the master cylinder fluid tank is mounted onto a drumlike device (what is this called?), which, I assume transitions and adapts the pedal motion to the cylinder. Does the liquid from the tank go into that drum as well? Because if it does, it could be that the drum is leaking somewhere.