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Clayso, Master Automobile Technician
Category: Car
Satisfied Customers: 880
Experience:  ASE Master Certified Automobile Technician. 30 Years Experience.
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I have pedal brake problem it goes very low to start br

Customer Question

Hi I have pedal brake problem it goes very low to start brake
Submitted: 2 years ago.
Category: Car
Expert:  Clayso replied 2 years ago.
Hi There, I'm Clayso a certified master automobile technician with 30 years of automotive repair and diagnostic experience and I'm here to help with this problem. Additional services may be offered for detailed information.
There are several things that can cause a low pedal. If there is air in the system. With the engine off pump the pedal, if the pedal pumps up there is air in the system or the rubber brake hoses are expanding.
There are 4 rubber brake hoses, one at each wheel clipped to the side of each strut. Check these hoses for cracks and breaks in the insulation cover. Cracks and breaks in the insulation cover are a good indication that the hoses are worn and most likely expanding during braking and should be replaced.
I see you have replaced the rear shoes and drums, if the parking brake sets low and tight the rear brakes are adjusted and should not cause a low pedal.
Under the dash where the brake booster connects to the pedal there is an adjusting nut for brake pedal height. If the brake booster has ever been changed or this adjustment has been changed, this will affect pedal height. Also at the booster under the hood there should be an adjustment in between the master cylinder and the booster. This adjustment is used to control the power assist to the master cylinder. A special tool is used to set the rods depth to the master cylinders bore.
The master cylinder can cause a low pedal if it's leaking internally or into the booster from the back of the of the master cylinder. The only check you can really do is to pull the master cylinder away from the booster and see if there is any fluid seeping at the master cylinders bore.
If you have ABS and no lights are on the ABS system is working properly and should not be a problem.
Before making any adjustments at the booster or master cylinder the system should be operating properly. Properly adjusted rear shoes, no air in the system, the brake hoses are good and the master cylinder shows no sign of leaking. Improper adjustments at the booster and master cylinder can leave you with no pedal or locked up brakes when the brake fluid heats up and expands in the system.
Also flushing the brake systems fluid with clean fluid will improve the brakes performance. Brake fluid absorbs moisture if left open to the outside air, to much moisture content in brake fluid lessens the fluids ability to dissipate heat and perform properly.
I hope this information is helpful to you.
Should you have any questions please let me know.
Thanks so much.
Expert:  Clayso replied 2 years ago.
Hi There,
You last viewed this thread on June the 8th, and I hope the information I gave was helpful. Let me know if you have followed through with my recommendations.
If you have any questions, please let me know.
Thanks so much.
Customer: replied 2 years ago.
Hi Clayso,Unfortunately the brake is still the problem.I am preparing a list of things that was made and when it is ready I'll send for you.Thanks
Expert:  Clayso replied 2 years ago.
Hi Luigi,
Once you get your list together let me know. A quick check to determine if the problem is at the wheels, is to pinch each of the four brake hoses and see if the pedal changes.
Let me know
Customer: replied 2 years ago.
Hi Clayso,
Here's what I did on the brakes.
I changed:1) The master cylinder
2) The cylinder of the rear wheels
3) The calipers of the front wheelsThe hoses according to the mechanic are good condition.
The adjustment between the pedal and the booster was never changed.
Please can you tell me how to check if there is any adjustment between the master cylinder and the booster, however, has some adjustment has never changed.
I noticed however that when the engine is stopped and stepped on the pedal a few times, the brake is always hard not flexible as if it had air in the system.
But if we waited a while and step on the pedal again the first time, is lower than the last time.
In the end we just need to change the hoses or the car, because the brake is still a problem.Thanks Luigi
Expert:  Clayso replied 2 years ago.
Hi Luigi,
Yes I would change out the flexible hoses, any expansion in the hose would allow the pedal to be low. I would do this before attempting to make any mechanical adjustments to the pedal height.
To check any adjustment between the master cylinder and the booster. The master cylinder has to be unbolted and pulled away from the booster. If there is an adjustment it will be on a rod in between the master cylinder and the booster.
Let me know how this works out for you.
Positive ratings are greatly appreciated.
Thanks so much.