Car off, brake pedal does not stiffen up
10-22-15, 04:41 PM
#1
Lead Lap
Thread Starter
Car off, brake pedal does not stiffen up
I have been more in tune to my braking system since my wife said my car takes for ever to stop. I noticed it too and bleed the system strategically from rear to front (RR, RL, FR, FL). I do not have air but my soft brake problem still persist. I noticed stepping on the brake when the car is off should stiffen up the pedal, but it does not. I also noticed a spongy/springy noise at the beginning of depressing the brake pedal. Any idea?
10-22-15, 05:16 PM
#2
You must have a leak somewhere. Any lost in fluid at all? If the system has no leak, then make sure that you bleed the system correctly. Have 2 person system is best, one to pump them hold, and the other person release and retighten the nut, repeat 10 times, or more until no more air coming out. Make sure to not let the fluid in the reservoir running low, keep refilling it with new fluid. Post back the result.
10-22-15, 05:28 PM
#3
With the engine off, the brake pedal must be pumped multiple times before it will get hard. The vacuum built up in the booster is retained even with the engine off so you will still have several pedal depressions with power assist before it gets hard.
I would first inspect the level and condition of the brake fluid in the reservoir. Is it clean and clear or do you see black debris or a blackish color to the fluid?
Also inspect the condition of the brake rotors. They should be smooth and free of rust pits. Any excessive pitting or rust on the braking surface will drastically reduce your brake efficiency. You should also look at the thickness of the pads although pad thickness will not effect the feel or performance of the brake system.
If all of the above looks good then your problem is likely in the master cylinder assembly. If the master cylinder is failing, you will not get the correct fluid pressure to the calipers. There are a few methods to checking the master cylinder that are fairly easy.
The first would be to start the car, apply light to moderate pressure to the pedal and observe its travel. The pedal should travel no more than 2/3 of the entire possible travel. 1/3 is ideal but 2/3 is acceptable. If your master is bad, the pedal will usually travel slowly all the way to the floor with continuous pressure applied.
Another way would be to unbolt the master from the booster, pull it slightly forward and inspect the back side of the master for brake fluid. If the cylinder is failing, it usually leaks out the back side. You can also remove the vacuum supply line from the booster and use a zip tie like a dipstick to see if there is any brake fluid at the bottom of the booster.
If none of the above mentioned tests yield any negative results, then I would recommend taking the vehicle in for professional service. The brake system is THE most important system on the vehicle and should not be taken lightly.
I would first inspect the level and condition of the brake fluid in the reservoir. Is it clean and clear or do you see black debris or a blackish color to the fluid?
Also inspect the condition of the brake rotors. They should be smooth and free of rust pits. Any excessive pitting or rust on the braking surface will drastically reduce your brake efficiency. You should also look at the thickness of the pads although pad thickness will not effect the feel or performance of the brake system.
If all of the above looks good then your problem is likely in the master cylinder assembly. If the master cylinder is failing, you will not get the correct fluid pressure to the calipers. There are a few methods to checking the master cylinder that are fairly easy.
The first would be to start the car, apply light to moderate pressure to the pedal and observe its travel. The pedal should travel no more than 2/3 of the entire possible travel. 1/3 is ideal but 2/3 is acceptable. If your master is bad, the pedal will usually travel slowly all the way to the floor with continuous pressure applied.
Another way would be to unbolt the master from the booster, pull it slightly forward and inspect the back side of the master for brake fluid. If the cylinder is failing, it usually leaks out the back side. You can also remove the vacuum supply line from the booster and use a zip tie like a dipstick to see if there is any brake fluid at the bottom of the booster.
If none of the above mentioned tests yield any negative results, then I would recommend taking the vehicle in for professional service. The brake system is THE most important system on the vehicle and should not be taken lightly.
10-22-15, 05:36 PM
#4
And just to clarify correct procedures, NEVER, under any circumstances should you pump your brake pedal while bleeding. If there is air in the system, pumping the pedal only scatters the air around. The advice given above is incorrect.
Gravity bleed each wheel first. With the cap off the master, open one bleeder (makes no difference which one) until you see constant drips from the bleeder. Once you have done this at each wheel, then get an assistant to push the brake pedal for you. Open the bleeder, press pedal down, then close the bleeder and release pedal. Wait 10 seconds or so after closing the bleeder before you open it again to prevent sucking air in when the bleeder is open. Repeat this at each wheel and your system should be correctly bled.
For what its worth, from your description, it doesn't sound like an air problem. More likely poor rotor condition or master failure. Are the brakes noisy when applied? Any vibrations?
Gravity bleed each wheel first. With the cap off the master, open one bleeder (makes no difference which one) until you see constant drips from the bleeder. Once you have done this at each wheel, then get an assistant to push the brake pedal for you. Open the bleeder, press pedal down, then close the bleeder and release pedal. Wait 10 seconds or so after closing the bleeder before you open it again to prevent sucking air in when the bleeder is open. Repeat this at each wheel and your system should be correctly bled.
For what its worth, from your description, it doesn't sound like an air problem. More likely poor rotor condition or master failure. Are the brakes noisy when applied? Any vibrations?
Trending Topics
10-22-15, 09:12 PM
#8
Lead Lap
Thread Starter
thanks for the advice. I never have an issue losing fluid and it is still clean. i resurfaced my rotors and replaced my pads about 1 month ago. shortly after i bled all the brakes according to a DIY on this forum. The procedure for bleeding is similar to what has been described by Gdwrench35. I am considering picking up a simple, yet effective, brake bleed and vacuum pump since my assistant is too lazy. they have this on amazon
If this fails i need to look at the master. Is there a DIY for inspecting the master?
10-23-15, 06:35 AM
#9
I bleed my brakes by myself using a long broom handle to pump the brake pedal while I watch for bubbles (don't judge me, bro).
Inspect your caliper guide pins also. If one or more are rusted/frozen it could impact you braking.
my $.02
Inspect your caliper guide pins also. If one or more are rusted/frozen it could impact you braking.
my $.02
10-23-15, 05:09 PM
#10
Frozen or sticky slide pins usually give you a hard pedal, not soft, but still worth checking.
If your problem was air related (air in the brake fluid) then pumping your pedal multiple times rapidly would temporarily alleviate the soft pedal issue. If the pedal feels the same every time you hit it, its not air. If it gets better with repetitive pumps, then its air.
If your problem was air related (air in the brake fluid) then pumping your pedal multiple times rapidly would temporarily alleviate the soft pedal issue. If the pedal feels the same every time you hit it, its not air. If it gets better with repetitive pumps, then its air.
10-23-15, 09:15 PM
#11
Lead Lap
Thread Starter
I just tested my brakes pedal again with the car off and it definitely gets makes a noise and i step on the brakes. It makes a spongy sound when i press on the pedal. The sound is more noticeable as I take my feet off the the pedal and let it raise back to normal position, like it is sucking in air. The other thing i noticed is that the pedal does not get harder, but instead it gets harder and i never have a lost of fluid.
10-24-15, 09:16 AM
#13
Lead Lap
Thread Starter
interesting you ask. as i depress the brake pedal about 5 times, i no longer hear the air sucking noise and the pedal becomes softer and travels further back. As i let the pedal go i do hear the air sucking noise. Also, after about 5 time and the pedal travels further, i start the car and the pedal does pushes itself upward a bit while my feet it on the pedal.
10-24-15, 12:34 PM
#15
Lead Lap
Thread Starter