Hey there, so i was driving around and my brake light came on so i checked my brake fluid and it was completely empty. I didn’t think anything of it so i just filled it up and it was fine for about a week until a few days ago my light came on again and yet again it was empty. This time i did not fill it up and instead tried looking for a leak but could not find one. I put a little bit into the reservoir and slammed on my brakes with the car off and still did not see a leak. I took the check valve off of my brake booster to see if i could find any liquid in there and I couldn’t tell if i did or not, the towel seemed a bit damp but I couldn’t tell. Now when i try to start it, it wont turn over. I believe it could be leaking into my master cylinder but im not 100% sure, how could i check?

 

How hard is the brake pedal when trying to start? Stiffer than normal? You might try to apply more force. Does the push start button light up at all?

 

it does light up so its not a electrical issue. My brakes are super stiff but its usually like that before i start my car.

 

When these cars don't crank it's electrical.

Where exactly are you checking for leaks besides booster? There's brake hard lines, rubber hoses to calipers, seals....etc

 

Sorry it cranks but it doesn’t turn over. Well i checked the rubber hoses to the calipers and those didn’t have a leak, and i couldn’t find anything. I looked around the car as much as i could. Underneath the car I couldn’t find any leakage. If it was a seal or brake line my car would’ve probably at least started but im just lost now.

 

Look at the bleeding screws on all calipers. Make sure those are tight.

 

I'm thinking you need to pull the MC and seal at the booster. Essentially pull the plunger out and and carefully dip something like a coated piece of wire in there. However as soon as you pull the MC out and, usually you will know it's leaking as it'll be all wet.

Has it had brake fluid flushes every 4 years? What's the history? If say it's been through a few pad slaps where the caliper pistons were crammed back in their hole without being bled, it's prime candidate for MC failure. Be careful driving it as the pedal might just go right to the floor.

** honestly, DON'T DRIVE IT until this is resolved!! **

I suspect the ABS module would be the next likelysuspect if no calipers are leaking. It has an accumulator and diaphragm. I'd suspect it would shoot an an error if it were bleeding off pressure internally.

 

Put few cardboards under the car, press the brake pedal few times, in the morning check for leaks. Also see the inside wheels for wet spots.