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I think activated ABS. But since then the brake pedal goes to the floor and feels spongy.

Tiny
TAILSPIN123
  • MEMBER
  • 2014 HYUNDAI SONATA
  • 2.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 62,000 MILES
Right after my car's 60,000 miles warranty expired, I got this brake pedal problem, everything was working fine. Our freeway condition is pretty poor while driving I had to brake and the bumpy ride I think activated ABS. But since then the brake pedal goes to the floor and feels spongy.

I took it to different shops for inspection and one shop suggested to change front rotors, brakes pads and brake flush, which I think was not needed but eventually performed the work to fix the pedal issue.

Replacing rotors and brake pads did not fix the issue next he suggested brake master cylinder is bad. So I ordered a brand new OEM master cylinder from Hyundai dealership. He installed it and performed bleeding the brake system multiple times with no success.

After spending so much time and money I don't feel comfortable to have him work on my car and want to do it myself. I have already performed bleeding one more time myself but still, brake pedal goes to the floor and is spongy.

if I pump it while driving, it builds up the pressure but eventually starts going to floor once releasing pedal.
Also, after braking and releasing the pedal I hear a vacuum air sound like its filling the booster.

i am really out of options and looking if someone can point me in some direction on what to check next. I think the new master cylinder could be bad, but its unlikely since I bought it from the dealership and it's Hyundai genuine part. Not saying it can't happen but looking for a suggestion. I could get a replacement of master cylinder as it should be under warranty.

Any help is appreciated. It has been three weeks without a car.
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Tuesday, January 8th, 2019 AT 8:28 PM

19 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,935 POSTS
Hello,

It sound like the originally master was bad and the system has air trapped inside the ABS system unit. Can I ask if the new master was bench bled? If not here is a guide that will help:

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

and this guide can help as well:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

If the master was bench bleed you will need to connect a scan tool to manually open the ABS valve to release the air in the system.

Please run down these guides and report back. Please let us know what you find. We are interested to see what it is.
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Thursday, January 10th, 2019 AT 12:10 PM
Tiny
TAILSPIN123
  • MEMBER
  • 9 POSTS
Thank you for the response. I am not sure if the new brake master cylinder was bench bleed. I have requested a replacement to new master cylinder to see if the new master cylinder was bad. I will receive it next week and update you if that fixes the problem.

Wanted to ask if there is a way to bleed air out of break system without using bleeder valves on wheels. So that I don't have to remove all four wheels. It is difficult to raise car without a lift at home and use car jack.
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Thursday, January 10th, 2019 AT 5:25 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

No, there is not a way of bleeding without opening the bleeders. I would suspect there is air in the lines. These guides can help you fix it.

https://youtu.be/w7gUsj2us0U

and

https://youtu.be/WDxvEQrMkBg

and

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Please run down these guides and report back.
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Friday, January 11th, 2019 AT 9:27 AM
Tiny
TAILSPIN123
  • MEMBER
  • 9 POSTS
Hello,

I received new master cylinder yesterday and I replaced it and did bleed air two time. But it is still spongy. I see little difference but not as tight it should feel. If I pump the brake if works normally or if I hard press the pedal it keeps the pressure. But once I release the pedal the next pump pedal still goes to the floor. I did rent the vacuum bleeder but it did not suck oil out like I was expecting. The brake pedal bleed did push more fluid than vacuum pump.

Any other suggestions I could try?
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Saturday, January 19th, 2019 AT 4:04 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You need a pressure bleeder not a vacuum bleeder. Big difference. You have air trapped in the line.

Roy
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Saturday, January 19th, 2019 AT 4:06 PM
Tiny
TAILSPIN123
  • MEMBER
  • 9 POSTS
Do you know how it looks. Because i asked for the same. But they said this the pressure bleeder.

Here is the link of what they gave me:

https://shop.advanceautoparts.com/p/powerbuilt-tools-kit-29-vacuum-pump-brake-bleeding-kit-22-piece-648744/9150047-P?searchTerm=Powerbuilt+vaccum+pump
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Saturday, January 19th, 2019 AT 4:23 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Nope that's not the correct one. You need a pressure bleeder. That's a vacuum bleeder

Roy
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Saturday, January 19th, 2019 AT 5:24 PM
Tiny
TAILSPIN123
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Can you send me a link on how it looks like?

Do you think there could be any other issues than air in lines?
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Saturday, January 19th, 2019 AT 5:49 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
First you need to bleed the system of all air. That parts store has no idea what a pressure bleeder is. You need another parts store.

Roy
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Saturday, January 19th, 2019 AT 5:52 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,935 POSTS
I have seen a seized caliper mount cause this issue. Can you confirm all calipers are moving freely? Also, I would try four vise grips with rubber tubes over the jaws and gently close off the rubber flex hoses to see if the pedal improves. Also, did you try a scanner to open the ABS valves while bleeding?
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Monday, January 21st, 2019 AT 10:08 AM
Tiny
TAILSPIN123
  • MEMBER
  • 9 POSTS
How to check if calipers are moving freely? Sorry haven't done that before.
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Monday, January 21st, 2019 AT 11:32 AM
Tiny
ASEMASTER6371
  • MECHANIC
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I attached a link to a pressure bleeder so you will see what it looks like.

Roy

https://www.tooltopia.com/mityvac-mv6840.aspx?utm_source=google&utm_medium=cpc&utm_campaign=paid_search_google_pla&adpos=1o1&scid=scplpMITMV6840&sc_intid=MITMV6840&gclid=Cj0KCQiA-JXiBRCpARIsAGqF8wXy6nBySPrCAtHJmuHgjeXioaWmICguyTEBC5AS777ZmABUzMWm8zIaAjKGEALw_wcB
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Monday, January 21st, 2019 AT 12:02 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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You remove each wheel back the pads up inside the calipers, they should then move freely back and forth. This guide shows how to service the slides so you can see what I am talking about.

https://www.2carpros.com/articles/how-to-replace-front-brake-pads-and-rotors-fwd

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Tuesday, January 22nd, 2019 AT 9:58 AM
Tiny
TAILSPIN123
  • MEMBER
  • 9 POSTS
The brake bleeder screw lost the thread and I took the vehicle to dealership. He is saying I need new caliper that is obvious. But he is also saying the hecu or abs control unit is bad and needs to be replaced to fix the pedal issue as that is not building pressure I dont believe that and which he is quoting me $1500. I thought breaks work with oil and not with some external pressure. Do you think any of the above symptoms related to abs unit? There is no abs light on. Or they are just trying to get money out of me? Plz if someone can reply quickly that will help me to decide.
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Thursday, January 24th, 2019 AT 10:37 AM
Tiny
ASEMASTER6371
  • MECHANIC
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It is possible. It sounds like there is air in the system.

I would start by having them replace the caliper first and bleed the system and see if you get a pedal.

It is not common for the ABS module to make the system not have a good pedal.

Roy
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Thursday, January 24th, 2019 AT 10:47 AM
Tiny
TAILSPIN123
  • MEMBER
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He is saying thats "the module that build up pressure. And they kind of covered the bleeder screw to check if the pressure was building and the conclusion was it is not building pressure." I think he is lying so I asked him to give me the old abs module and I was wondering is there a way I can get that checked and if it is not bad I can ask to return my money.
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Thursday, January 24th, 2019 AT 5:45 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
No, there is not unless you have special equipment to check that system. It has solenoids and valves inside.

Did they repair the car already?

Roy
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Thursday, January 24th, 2019 AT 6:38 PM
Tiny
TAILSPIN123
  • MEMBER
  • 9 POSTS
No parts are being ordered it will come on Monday. But car is at the dealership
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Thursday, January 24th, 2019 AT 6:56 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
As I state before, Have him just do the caliper with the bad bleeder and bleed the system. He needs the scan tool to do the automated bleed for the ABS.

Otherwise, remove it and take it somewhere else for another opinion and a much cheaper price.

Roy
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Thursday, January 24th, 2019 AT 7:04 PM

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