Hey, so i had a scary experience today.
I had my BRAKE light pop up in my interior dash for the last few days. i didnt think nothing much of it. I thought perhaps my sensor was broken but it seems that my Master Cylinder was low in Brake Fluid.
One thing i noticed, was the master cylinder cap was loose. 2 months ago, I changed everything in the rear brakes including the wheel cylinders. I filled the Master Cylinder to the top.
Now it was low.

Before i go crazy and start taking off all the wheels and checking the drums and lines for leaks. Do you think its possible that a loose Master Cylinder cap could cause a low amount of brake fluid? Does brake fluid tend to evaporate quickly?
When i looked around the master cylinder cap area i did not see any oily fluid residue. Everything seemed pretty dry. Not sure if it emptied a month ago and within a month time frame it evaporated and doesnt show.

If i should still be seeing fluid then i guess the issue might be brake lines, inside the drums or calipers.
I just dont want to have to do all the heavy lifting of checking everything.. im hoping it was just the cap.

But if someone with experience knows what i should do next or what it could be then that would be great.

 

Brake fluid doesn't evaporate.

Refill and monitor. Likely it is leaky wheel cylinders.