I have a 2003 honda civic ex with about 150K on it. I recently replaced the head gasket, of course messing with the fire wall and all the hoses, brake booster/brake lines that sort of thing so maybe that is what is causing the issue. As the title says when I press on the brakes they go all the way to floor and the car slows very gradually, pressing it all the way down hardly seems to make much of an affect on the car. Not entirely sure what is causing this issue. I keep reading that it could be one of three things, the master-cylinder is broken, break-booster is bad, or there is a leak somewhere in the vacuum tubes. There is no leak on the floor of the car, area nearing the master-cylinder. When I check the brake fluid, it is not topped off. But as far as I know brake fluid doesn't just go as a result of general wear and tear, right? It goes for specific reasons such as a leak somewhere.

Also, I have not replaced the brakes ever on this car and I know the driver side is basically completely gone. However the passenger is still good. Could having the driver side rotor/pads be worn down cause this problem? What would cause the brake fluid to be missing?

And since this the right brake light has stayed on. The same one that would come on if I pulled the emergency brake. It's weird because a week ago the brakes seemed fine, not great but nothing like having to pressed the pedal all the way to the floor to get a response. It just all the sudden happened one day.

Also, don't worry I am not driving this car. It's something I am wanting to fix up, and fix right.

Thank you

  • What does "When I check the brake fluid, it is not topped off." mean? Has the level of brake fluid in the reservoir gone down, or does the reservoir still appear full? Commented Dec 30, 2017 at 0:34
  • @David The brake fluid in the reservoir has gone down.
    – yre
    Commented Dec 30, 2017 at 0:39

2 Answers 2


If the brake light is on, the fluid is low, and the pads are gone, you need to put new pads on it and see if this remedies the issue. IOW: Fix what you know is wrong, because these are going to have to be fixed anyway. This may or may not fix the overall issue, but it takes one piece of the pie out of the mix.

As for the low brake fluid. When the brakes are worn down to nothing, the caliper piston extends further out of the caliper. Something has to fill the void. What might this be? That's right, it's brake fluid. This could be where all of its gone, especially if you're not seeing a leak on the floor/ground.

If your pads are as shot as you think they are, plan on changing out the brake rotors while you're at it. If all of the friction material is gone and it is now riding metal-on-metal, you pretty much don't have any other choice. This will more than likely cause irreparable damage to the rotor and quite possibly the calliper besides.

Also, the reason the brake light is on is because the fluid is low in the master cylinder. There's a level sensor in there which will illuminate the brake light (yah, the same one as the e-brake does). Once there's enough fluid in the master, it should raise the sensor and the light should go off. If it doesn't, then you have other issues (obviously). Do NOT just add brake fluid to the reservoir. When you collapse the calipers to replace the brake pads, fluid will be pushed back up into the reservoir. If you've place more fluid into the reservoir, it will get pushed out and get all over everything. Brake fluid will destroy paint, so if it gets onto any finished surfaces, you'd have to clean it off quickly or it will suffer damage.

Even if the passenger side brakes are "good", replace both sides at the same time. This will ensure things are even in the braking department and will keep the car operating correctly.

  • Thank you. I will go ahead and purchase new brake pads and rotors for the car and see if that fixes it. I'll have to wait a week until I get paid to have this happen those, and then a few days for the amazon delivery. Never installed brakes before. Anything I should be advised of? I have done more involved work to this car like replacing the cylinder head, but strangely enough not the brakes. Just didn't get around to it. Am sure the pads are toast. So the brake fluids basically tends to go along with the wearing down of the pads it sounds like?
    – yre
    Commented Dec 30, 2017 at 6:07

From the description of the onset of your problem that it was fine and then a sudden dramatic change in braking pedal feel and braking stopping power it is highly likely.you have a leak in the brake fluid pipes or the brake pistons themselves. Undiagnosed and uncorrected this is extremely dangerous. You have to find the leak, check each wheel for fluid check each fitting from the master cylinder piston to any fittings stops along the tube. Like immediately. If you can't find it, get brake fluid top off the reservoir and bleed each wheel piston of air bubbles with a vacuum pressure bleed tool. Then with the wheels and car securely lodged press the brakes again and again until you are sure the brake fluid is not leaking and the reservoir stays full and the pedal feel is firm.

  • Thank you. I have changed the brakes (the physical aspect) but now I just need to top off the brake fluid and then bleed the brakes. After that is all said and done do you think I should lay out some cardboard under each wheel and pump the brakes and see if I notice any leaks? I've never traced out a leak before so I don't know how this might be done.
    – yre
    Commented Jan 30, 2018 at 21:37
  • Look for fluid at each piston so where you changed the pads is there any liquid on the seal around the round metal inside of the piston that contacts the back of the pad, check the back wheel just get in there with a light and look. Check the floor area near the foot pedal for wetness. Check around the master cylinder piston under the hood, follow any brake pipe and see if you find any liquid, check where the pipe connects to anything like ABS system or changes from hard metal pipe to flexible rubber pipe. Bleed, pump for 50 strokes or 5 mins and check the reservoir it shouldnt be losing ANY. Commented Jan 30, 2018 at 23:39
  • If youre not losing any and the pedal stays firm after bleeding should be good to go. The onset of your brake issue indicates a leak. There is nothing as dangerous as faulty brakes, even faulty steering or a broken suspension at high speed you might be able to control the vehicle, loss of brakes when you have 100 ft to go from 60 to 0 is catastrophic. Commented Jan 30, 2018 at 23:44
  • I want to be as safe as possible here. I read that when pads get very low (like mine) that all the brake fluid can come rushing down into the pads area? yeah...sorry just not sure how that all works. But maybe that could account for where the brake fluid went. When I looked the piston, the thing I had to compress with a c-clamp, I didn't notice any brake fluid there. When you say look for fluid at each piston, you mean the part that had to be compressed with the c-clamp, right?
    – yre
    Commented Jan 31, 2018 at 14:36
  • @yre Yeah, when the pads are low and piston is extended then there is more fluid in there and a little less in the reservoir so you may need to top off maybe 200m/L. What I would be concerned about it that you suddenly noticed the loss of brake stopping power, and you suddenly noticed the pedal feel was very different. That is typically not a pad wear symptom, usually you will hear the soft metal wear indicator go off or notice braking stopping reduction, but not pedal feel. Commented Jan 31, 2018 at 17:03

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