# 2007 lincoln mkx soft brake pedal



## Rob_hdz1994 (Feb 24, 2018)

I need help finding the problem with the brake pedal too soft and goes in with not braking properly. There is no leaks on the brake line that goes to the calibers and don't see any spots on the floor. I bled all four calibers twice and it still the same. I checked the master cylinder, took the hoses out and plug it with two bolts to isolate the mc. Hit the pedal a few times and got hard so I believe that is not the problem. I did a smoke test on the hose that goes to the booster brake and smoke came out from the throtle body only. Once the car is on and press the brake at a certain pressure there is a squeaky very loud noise that stays on until you let go of brake or push a bit further. I believe it to come from the booster brake but there was no smoke leak. The only thing that I have left to check is the abs system but I wanted to see if you guys have any ideas and maybe let me know if I checked the parts correctly? Also when I plugged the master cylinder with the two bolts and took the one closer to the booster brake it was dripping and the one closer to the battery was not leaking could this be a problem? Thank you


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## CrazyGuy (Nov 18, 2017)

I think that you need to keep bleeding it. Twice is not enough sometimes. Fill up the reservoir and open all bleeders and let it gravity bleed for a while, just keep an eye on the fluid level, don't let it run out.

In my opinion it is always best to bleed the old fashioned way with two people rather than an self bleeder tools. Make sure that your pedal pusher knows what to do. (pump it several times, hold it, open bleeder, pedal completely to the floor, tight bleeder and repeat). It can take several attempts sometimes.


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## Rob_hdz1994 (Feb 24, 2018)

I bled a few times in each caliber with another person on the four tires and did it twice that's what I meant. I used about 3 qts of brake fluid in total.


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## CrazyGuy (Nov 18, 2017)

Rob_hdz1994 said:


> I bled a few times in each caliber with another person on the four tires and did it twice that's what I meant. I used about 3 qts of brake fluid in total.


Somethings not right here. A few bleeds on each caliper done twice should not use up 3 qts of fluid. Are you sure it is not leaking somewhere? Are you sure you are using a proper bleeding procedure? If not leaking anywhere, keep bleeding as I suggested.


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## Bigplanz (Apr 10, 2009)

My guess is this is ABS related. Some cars require cycling the ABS with a scan tool to bleed.


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## Brainbucket (Mar 30, 2015)

I need to know 2 things before I can give an intelligent diagnosis. Was there any repairs done before symptom and if so, what?:glasses:


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## Rob_hdz1994 (Feb 24, 2018)

I believe to have found the problem!? So I took the driver front tire off and got the caliber out. I used one brake pad and used a brake tool to push the caliber in as if I was to change the break pads (can't think of the tool name) and brake fluid started dripping to the floor. I got under the hood and saw wet around where the mc and booster meet and also I noticed a drip not from the hose closer to the booster but just right above it. Could it be just the mc reservoir seal or would I have to replace the entire mc with also booster brake seal?


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## Rob_hdz1994 (Feb 24, 2018)

I took mc apart and took pictures. The red area is dirty I believe it is where the leak on the booster is from. The blue area is the fluid reservoir and I think thats where the dripping is coming from. Maybe I need to replace the whole mc with reservoir?


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## CrazyGuy (Nov 18, 2017)

When you compressed the caliper it may have just pushed fluid out of the top of the reservoir if the cap was off. That would be normal if the master cylinder was overfilled or if you compressed it quickly.

If there is fluid leaking out around the seal where you have the red circle (where push rod touches), then the master cylinder is not good and get another one.


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## Rob_hdz1994 (Feb 24, 2018)

Finally found the problem. After I inspected the brake pedal one last time I noticed once brake pedal was depressed at idle it was a bit rough. The rmp was moving up when depressed at a certain pressure. After replacing master cylinder and still having the problem I decided that it could only be the brake booster so I replaced it, bled the brake lines one more time and it finally fix the soft pedal. After inspecting the old brake booster I noticed the rod was a bit loose and where the check valve goes in it was not sealing properly. Hope this helps somebody else with a similar problem and thank you all for your help!


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