Hissing Sound and Steam from Master Cylinder Area

[MrBonus]

I was doing a shakedown run on another issue (that I failed to fix for what it's worth) and when I pulled into the garage, I gave the brakes a few hard pushes to test my brake lights.

Well on the second brake push, I felt the brake pedal go deep into the footwell and hissing/steam coming out of the master cylinder.

I'm assuming the master cylinder failed on me? I'm glad it happened parked in the garage and not on the road.

[pharriso]

Not sure how steam would come out of a master cylinder... you need to check for dragons under the hood! (Bonnet)

[MrBonus]

Not sure how steam would come out of a master cylinder... you need to check for dragons under the hood! (Bonnet)

Me neither!

I of course hit the brakes again with the engine off as I thought it was smoke which I didn?t smell and I definitely saw steam rise out of the region once I removed the bonnet.

After the car cooled down a bit, I could still hear the hissing when I hit the brakes.

[SENC]

Assuming a left hand drive, my bet is a hydraulic fluid leak from the master cylinder onto the exhaust manifold, which then steamed. Could also be unrelated symptoms so also look to the thermostat/water return valve as another potential area of leaking that can would result in steam from a hot manifold.

When you opened the master cylinder, does it look low? Look and feelmaround it for leaks, should be fairly obvious. Does pumping the pedal bring back firmness? Have someone pump while you watch.

[MrBonus]

Assuming a left hand drive, my bet is a hydraulic fluid leak from the master cylinder onto the exhaust manifold, which then steamed. Could also be unrelated symptoms so also look to the thermostat/water return valve as another potential area of leaking that can would result in steam from a hot manifold.

When you opened the master cylinder, does it look low? Look and feelmaround it for leaks, should be fairly obvious. Does pumping the pedal bring back firmness? Have someone pump while you watch.

SENC, after calming down and taking a look, it looks like I sprung a hydraulic fluid leak somewhere and as you mentioned, it shot on somewhere hot under the hood. There is a nice puddle underneath the driver's side steering arm and a bit on the frame.

I'll jack it up this weekend and take a look. I checked the master cylinder however and it didn't look particularly low. I need a second set of eyes while I pump the brakes to see if I can isolate the leak.

Regardless, I was still in fight or flight mode when I made this thread in a panic.

[2cams70]

Rinse away with water straight away - brake fluid is a great paint stripper!