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cloe0626, Auto Mechanic
Category: Nissan
Satisfied Customers: 819
Experience:  was a mechanic in the army for four years and have been working at a dealer ship the past five years
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I've only got half my brake pedal after replacing the front

Customer Question

I've only got half my brake pedal after replacing the front calipers and rotors. I've bleed it 3 times with no improvement to the pedal. I didn't bleed the LSV and not sure how to do it. I've even thought it was the master cylinder or the booster.
Submitted: 1 year ago.
Category: Nissan
Expert:  cloe0626 replied 1 year ago.

sounds like the master cylinder needs to be bleed

Expert:  cloe0626 replied 1 year ago.

Clamp the cylinder firmly in a bench vise so that the cylinder area is level. If it is pointing upwards the air will remain in the cylinder. Slide the hoses onto the fittings. Cut the hoses just long enough to reach into the reservoirs and remain submerged - the shorter the length of hose the better. Place the other ends of the hoses into the fluid reservoirs (you'll probably have hold them in place somehow because once you start pumping they'll want to flail around in the air and spray brake fluid everywhere). If you can get a helper that is ideal.

Fill the reservoirs with new brake fluid, and pump the piston slowly and evenly, full strokes. I used a big Phillips screwdriver because its tip doesn't damage the piston and the handle gives you something to lean against. I would not worry about the fluid getting recirculated because it is brand new and you are creating a temporary hydraulic circuit with the hoses which will not become contaminated with dirt. The air which is still in the system at this point will be bled out. Pump the cylinder until the tubing contains no more air bubbles and no new ones emerge from the MC on the down stroke. On my MC this took about 15 strokes some may require more, some less. Keep going until the air stops as this will make the task of bleeding the brakes in the car much simpler. When all the air is out, mount the cylinder in the car. Here you have to be careful to prevent the fluid still in the hoses from spaying your car and any other painted objects nearby - brake fluid is a great paint remover! If you decide to remove the hoses before installing on the car, make sure to plug up the fittings - I just held the hoses up while transferring from bench to car. Once the MC is mounted in the car, remove the fittings and connect the brake lines. You'll lose a little fluid but the check valves in the cylinder should stop any major leakage. Now you are ready to bleed the brakes in your car and it should be a lot easier than if this step was avoided

Customer: replied 1 year ago.
Can I bleed it without removing it from the vehicle and how about the LSV (load sensing valve) does that play any part in trapping air?
Expert:  cloe0626 replied 1 year ago.

no it will have to be removed and the lsv would trap air in to the sensor