Soft brake still after MC replaced
Looking for some advice on my Infiniti M37.
A few months ago I notice my brake pedal was becoming soft. I had the car in for a oil change so I requested the brakes be bled. I hoped this would fix it. The pedal was still soft after. Talking to the shop they said they did a brake flush instead. I had them take it back in for the bleed job as I originally requested. Even after it was still soft. My father a 30 year GM mechanic said it sounds like a master cylinder. So yesterday 11/19 we replaced that. It was bench bled before install. We bled the lines going into the ABS module. We bled the brake lines themselves following the wheel pattern from the Nicoforum service manual. Go for a test drive it is still the same. Brought it back bled them again. Still the same. I can pump the brakes up while the car is off till it is hard. Once the car turns on it goes back down to the floor. Inspected the lines for leaks and cracks we did not see any. The master cylinder reservoir does not drop fluid. Totally at a loss for what is going wrong still. We called the Infiniti dealer for any advice they may have had. Service advisor said sounds like we have done all they would do too. They were unsure also.
So here I am. Any advice is appreciated. I am ready to have this fixed and behind me.
2011 M37x Brakes Still Soft After MC Replaced
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brian_wolf
- Posts: 1
- Joined: Sun Nov 20, 2022 6:40 am
- Car: 2011 Infiniti M37x
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VStar650CL
- Technical Expert
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- Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S
Re: 2011 M37x Brakes Still Soft After MC Replaced
The only place to go from there is to use plugs to isolate exactly where the problem is occurring. Start by plugging all 4 lines out of the ABS one at a time and see if any of them restore the pedal. If not, the wheel circuits are vindicated. Go upstream and plug each throw of the Master one at a time and see if either one (or both) restores the pedal. If so, the problem is in the ABS, most likely air trapped in an internal reservoir because of a stuck valve. If not, the problem is in the Master or booster (and that would be weird behavior for a booster).
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Yoda's Master
- Posts: 441
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2009 370z - Location: Rock in the middle of nowhere
Re: 2011 M37x Brakes Still Soft After MC Replaced
since you changed the major part already, why don't to also try replacing the check valve on the vacuum to the top of the MC. might be a vacuum issue.
but.....i would say go bleed the brakes several more rounds before buying anymore parts. I had soft brakes until i bled the fk out of it. I used a power bleeder https://www.amazon.com/gp/product/B00CJ5DZE2
but.....i would say go bleed the brakes several more rounds before buying anymore parts. I had soft brakes until i bled the fk out of it. I used a power bleeder https://www.amazon.com/gp/product/B00CJ5DZE2
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reggiebrown40
- Posts: 297
- Joined: Mon Oct 13, 2008 12:01 pm
- Car: 2018 Infiniti Q60 Red Sport
2011 Infiniti M56x - Dead
Re: 2011 M37x Brakes Still Soft After MC Replaced
Sounds like the ABS module is not being bled properly or is faulty.brian_wolf wrote: ↑Sun Nov 20, 2022 7:42 amSoft brake still after MC replaced
Looking for some advice on my Infiniti M37.
A few months ago I notice my brake pedal was becoming soft. I had the car in for a oil change so I requested the brakes be bled. I hoped this would fix it. The pedal was still soft after. Talking to the shop they said they did a brake flush instead. I had them take it back in for the bleed job as I originally requested. Even after it was still soft. My father a 30 year GM mechanic said it sounds like a master cylinder. So yesterday 11/19 we replaced that. It was bench bled before install. We bled the lines going into the ABS module. We bled the brake lines themselves following the wheel pattern from the Nicoforum service manual. Go for a test drive it is still the same. Brought it back bled them again. Still the same. I can pump the brakes up while the car is off till it is hard. Once the car turns on it goes back down to the floor. Inspected the lines for leaks and cracks we did not see any. The master cylinder reservoir does not drop fluid. Totally at a loss for what is going wrong still. We called the Infiniti dealer for any advice they may have had. Service advisor said sounds like we have done all they would do too. They were unsure also.
So here I am. Any advice is appreciated. I am ready to have this fixed and behind me.
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