Document YrZ4eeGddV1Kg9MXeOBqeedV

BRAKE SYSTEM DIAGNOSIS AND TESTING Hydro-Boost System Inspection LESSON ONE-MODULE 1 Typical Hydro-Boost Master Cylinder (2002 F-250 Shown) Before testing hydro-boost components, check the engine and power steering for proper operation. If brake application and steering require excessive effort, the cause is likely related to power steering fluid pressure and delivery. Perform the following preliminary checks before testing the Hydro-Boost system: Check the fluid level in the power steering pump reservoir. Check the condition of the power steering fluid. If the fluid is dirty, smells burnt, or appears contaminated, flush and refill the system before proceeding. Inspect the power steering pump drive belt. Check the condition of the belt, belt tension and belt routing. Check all power steering hoses and lines for leaks. To verify if a leak exists, have an assistant run the engine at fast idle, apply the brakes and turn the steering wheel from stop-to-stop while you look for leaks. The high pressure developed should force fluid from small leaks. Possible leak points are lines and hoses, power steering pump, steering gear, or the hydro-boost unit. Repair all leaks. Check for proper brake fluid level and pedal operation. Bleed the brake system if necessary. Verify that the engine idle speed is correct. The hydro-boost system requires a constant supply of power steering fluid at the proper pressure and volume from the power steering pump. If all of the preliminary inspection steps listed previously are OK and there is still a concern, you may need to test the pressure developed by the power steering pump. Refer to the Workshop Manuals for steering system testing procedures. Hydro-Boost Functional Check: With the engine OFF, pump the brake pedal several times to relieve the hydraulic pressure stored in the accumulator. Apply firm pressure to the brake pedal.and turn the engine ON. The brake pedal should move downward, and then push up against your foot. Brake System Diagnosis and Repair September, 2005 7