I have a 2006 Ford Explorer XLT 4x4 with the v6 engine and around 160,000 miles on it. I hadn’t driven it for a few months because the harmonic balancer needed to be replaced and at the time fixing it wasn’t in the budget. Anyhow, once that got fixed, the next day I drove it to find out I had nearly no brakes. When the engine is off, the pedal is hard, but when it’s running it goes straight to the floor. I don’t see any signs of leaking anywhere and when I last drove it it seemed to be able to be pumped up but basically had to be pumped at each stop to have any braking at all. I have a second car that is my daily driver, but I’d like to get this Explorer roadworthy again before my oldest turns 16 next year and need to know which direction to go with it. Thanks in advance!
It sounds like air is in the brake hydraulic system, have the brakes "bleed", air should not be present in the system. There is a possibility the brake master cylinder is failing. Another less likely but possible reason is if the front wheel bearings are worn play in the wheel bearing can "push back the brake pads" giving a soft pedal on first press of the brake pedal and gets firm on second application of the pedal. This would be more noticeable after taking several sharp turns/winding road.
You have a leak somewhere in the brake system. Even after a car sits for few months, it shouldn't do that.
Also check the brake booster hose in the engine.
