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Having a soft brake pedal on any model is not safe nor is it a manufacturer issue. The mechanic telling you this sounds to be trying to get rid of you as he cannot fix the problem or possibly not doing something right. I will give you some things to check out then depending on the results I will hopefully be able to come up with a solution to help you out with your issue.
The first thing you need to do is to check the brake master cylinder level (I see you said you have no fluid loss but just need to get an idea of the fluid level, being I cannot see the vehicle it can be slightly tougher to diagnose). Is the level close to the max fluid level?
Next with the vehicle off, pump the brake pedal up until it becomes hard (if the pedal ever does become hard). Then with your foot still on the pedal, start the vehicle and note if the pedal drops fastly to the floor or not.
If you can pump the brake pedal up and the pedal becomes hard this will be a determining factor to tell if you have a hydraulic issue or possibly a faulty brake booster. If the pedal becomes hard then when you start the vehicle if the pedal drops this will indicate you have a vacuum issue which I will help you out in where to look next.
Also when the work has been done either time have you ever had a normal feeling brake pedal or have you always had the low pedal issue?
Also has the mechanic done anything else to the vehicle other then a master cylinder?
Please respond as soon as possibly so I can assist you to fix your issue! Thanks once again for choosing Just Answer!
Fluid level is at max in cylinder. Pumped breake pedal till firm and steady, started engine and pedal dropped to floor. tested 3 times, same result. stayed spungy while engine was running. The pedal became low, hence my original reason for the break service. It has not been normal during repairs.
The mechanic replaced pads, front rotors.
It sounds like your brake booster is faulty or possibly the vacuum to the booster. Being you can pump the brake pedal up and it becomes solid indicates you do not have a hydraulic leak or air in the system. I would rec for you to pull the vacuum line off of the brake booster and put your finger on the end to feel for vacuum. If you have no vacuum you will need to chase down the hose to find where the leak is coming from. You should feel vacuum while the vehicle is running. (Keep in mind the check engine light may come on if you have the engine running long enough with the hose off, don't worry the code will reset itself or you can disconnect the battery afterwords if you do not want to wait for it to clear). If you feel vacuum, shut off the vehicle then pull the plastic part off of the end of the tube (this is called a one way valve), blow through both ends. If you can blow through both ends you will need to start by replacing the one way check valve for the brake booster. You should only be able to blow air into the side going to the booster, and none the other way, this allows air into the booster but not allow it to escape. In some cases a faulty booster may have a hissing sound that you can hear from inside the vehicle which you can hear if you put your ear down where the rod connects to the brake pedal. The sound is mostly present when you hold the brake pedal down slightly. If you are not mechanically I would highly rec you find a different shop to work with as the mechanic who is currently working on it has no idea what he is doing. In no case is any vehicle safe, nor normal to have a spongy pedal. A brake system is a sealed system and will never just work itself to not being spongy. If you have any tire shops in the area you may call and see if they do free brake inspections, explain your situation and see if they would perform free diagnostics or not to fix your issue. If you have any questions or concerns please let me know! I am more than willing to help you out with your issue to make sure you are not taken for your money (if you decide the work is too hard for you), help you save as much money as possible, and guide you through the process to make the job as easy as possible!
Thanks for you advice. I am a bit taken back that my mechanic let this slip by. He has been really good in the past. Maybe he is too comfortable with my loyalty or too busy to perform proper diagnostics. Either way, unacceptable! Should the booster need replacement, is it difficult or do you reccommend a professional? I am skilled mechanically. Currently restoring my 1967 Cougar XR7.
If you have followed all of the above steps above and found that everything to the booster is good, then yes I would say the booster is the issue. In your case if you would like a second opinion to make sure that the booster is the issue, I would rec you talk with the mechanic who has worked on the vehicle to this point. Sometimes even a good mechanic has issues with diagnosing problems on vehicles with some components, or is rushed and forgets to check something. You should talk to him and tell him the issue was never fixed and has not gotten better to this point and mention you believe the booster is faulty and see if he will check it out at no charge (a good mechanic will do this for free as he has not fixed your problem right, and if you find a larger shop all costs that will be accrued now would be free. A large shop would charge nothing for parts and labor being they did not diagnose the issue correctly and have replaced a good part, or they would give your money back for the previous repairs). The booster is not extremely hard to replace if you would want to do the work yourself, but I would rec you talk with the mechanic first to see what your options are on the issue as he has not fixed your problem yet. If the mechanic is not willing to work with you at all then I would rec you find a better one if you need repairs later on, or you can use this site for help to fix your vehicle yourself! The book time to replace the booster is 1.6 hours. It is not too hard to replace.
I have attached the information on how to replace the booster, CLICK HERE ..... Being you have to remove the master cylinder you will need to bleed all 4 wheels when you are done. If you have any questions please let me know!
Brad. Thank you for all your advice. I will see my mechanic and get this fixed. He is good and I am sure we can work this out.
Glad I could help. If you have any questions or issues feel free to let me know! I will be more than happy to assist you. I work on here as a hobby to hopefully help people save money and not get taken from a shop. I could see a possibility where the mechanic may not be as familiar with Ford's over another model of vehicle and is not sure what to check or if he has a lot of vehicles maybe he is overwhelmed and did not have enough time to look it over properly. On the other hand he should have known better that a soft brake pedal that travels too far down is not a normal characteristic with any vehicle. Talk with him and see how it goes, if he will not work with you let me know and I will help you out the best I can to fix the car yourself. Thanks once again for choosing Just Answer!
To recap the above;
I would not suspect the hydraulic system to be faulty due to the fluid level being good and that you can receive pressure when the vehicle is off.
Check the vacuum supply to the brake booster and also the check valve.
Listen for air leaks (from the booster on the inside of the cab) while slowly pushing down on the brake pedal.
If the supply vacuum, check valve, and others check out ok. Then I would highly suspect the booster to be your issue.