Hissing sound from brake pedal?

[tdoyon]

My 2018 GT2 AWD developed an intermittent problem today. I was about a mile from my destination when the brake pedal began making a thud thud sound followed by hissing. The hissing stopped when I got off the brake pedal. It happened one more time but then stopped on subsequent tests (as I circled around the block trying to replicate it). The car hit 12,500 miles today and driving behind a Stinger in the Boston area is certainly not kind to the brakes... but this is a new one for me. I tried to check the brake fluid but can't figure out how to remove the black plastic around it (seriously Kia? seriously?????!!!!).

Is there a way to remove that black plastic? Is there something I should check aside from the brake fluid?

 

[CKeeler]

How often do you drive your car? Does it sit outside?
Possibility is that the discs developed surface rust from getting wet and then sitting. All the hissing you heard could have been the pads grinding the rust off.
Seeing that you have a 2018 and it only has a little over 12k miles on it, it may just have build up on the discs.

 

[tdoyon]

How often do you drive your car? Does it sit outside?
Possibility is that the discs developed surface rust from getting wet and then sitting. All the hissing you heard could have been the pads grinding the rust off.
Seeing that you have a 2018 and it only has a little over 12k miles on it, it may just have build up on the discs.

Not a bad idea but I had just driven into Boston and back (40 minutes one way) and I would have burned off the rust earlier avoiding an idiot in a white outback crossing over the double yellow lines. I would have burned off the rust before ever getting onto the highway.


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[CKeeler]

You’re right. That wouldn’t be it then. My wife’s car made a scraping sound when braking recently also. Hasn’t made it since though.
Keep an ear out for it to make that sound again. You might be able to track it down