5035644 JOHNSON *SCREW, IAC VALVE

Pressurized system: Hot coolant can cause serious burn. To open cap, stop engine, wait until radiator is cool. Then loosen cap slowly to relieve the pressure.
To relieve the pressure from the coolant system, move the engine start switch to the OFF position. Allow the cooling system pressure cap to cool. The cap must be cool enough to touch with a bare hand. Remove the cooling system pressure cap slowly in order to relieve pressure.Fuel System
To relieve the pressure from the fuel system, turn off the engine.High Pressure Fuel Lines (If Equipped)
Contact with high pressure fuel may cause fluid penetration and burn hazards. High pressure fuel spray may cause a fire hazard. Failure to follow these inspection, maintenance and service instructions may cause personal injury or death.
The high-pressure fuel lines are the fuel lines that are between the high-pressure fuel pump and the high-pressure fuel manifold and the fuel lines that are between the fuel manifold and cylinder head.These fuel lines are different from fuel lines on other fuel systems for the following reasons:
The high-pressure fuel lines are constantly charged with high pressure.
The internal pressures of the high-pressure fuel lines are higher than other types of fuel system.Before any service or repair is performed on the engine fuel lines, perform the following tasks:
Stop the engine.
Wait for 10 minutes.Note: Fuel pressure can be monitored by Caterpillar Electronic Technician (ET).Do not loosen the high-pressure fuel lines in order to purge trapped air from the fuel system.Engine Oil System
To relieve the pressure from the engine oil system, turn off the engine.Hydraulic System
Personal injury can result from hydraulic oil pressure and hot oil.Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.
Personal injury or death can result from sudden machine movement.Sudden movement of the machine can cause injury to persons on or near the machine.To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.
Park on a level surface and lower the work tools to the ground.
Engage the parking brake.
Shut off the engine.Hydraulic Oil Tanks
This machine has two separate hydraulic systems and two separate hydraulic oil tanks. Both hydraulic oil tanks are equipped with a breaker relief valve that is used to relieve pressure in each one of the hydraulic oil tanks.Reference: Refer to this Operation and Maintenance Manual, "Hydraulic System Oil (Implement) (Hydraulic Fan) - Change" for information about the location and operation of the breaker relief valve for the implement and hydraulic fan hydraulic system.Refer to this Operation and Maintenance Manual, "Hydraulic System Oil (Steering, Brake) - Change" for information about the location and operation of the breaker relief valve for the steering and brake hydraulic system.Slowly loosen the hydraulic oil tank filler cap of each hydraulic oil tank. This action will confirm that there is no build-up of pressure in either one of the hydraulic oil tanks.Implement System
Use the following procedures in order to release the hydraulic pressure from the implement system.
Make sure that the area around the machine is clear of personnel and obstructions before performing this procedure.
Turn the key to the ON position before moving the control levers.
Move the implement control levers through the full range of travel for each control lever. This procedure will relieve any pressure that may be present in the implement hydraulic system.
Move the engine start switch to the OFF position.Note: Additional procedures that provide for the manual release of implement system pressure are described in following sections of this article. Refer to "Lift Cylinder Circuit" and "Tilt Cylinder Circuit" in order to release the hydraulic system pressure from the appropriate circuit.Lift Cylinder Circuit
Personal injury or death may occur from failure to adhere to the following warnings.Keep all personnel away from the boom drop area when lowering the boom with the engine stopped.Keep all personnel away from the front linkage when lowering the boom.
Use the following procedure to release the lift cylinder hydraulic pressure manually.
Make sure that the area around the machine is clear of personnel and obstructions before performing this procedure.
Illustration 1 g03611076
Machine location and detail view of ball valve used to manually lower work tool.
A ball valve is used for manually lowering the work tool. This ball valve is located in the articulation joint on the left-hand side of the front frame of the machine. The ball valve is mounted on a bracket that is at nearly the same level as the drive shaft. Slowly turn the square stem in the clockwise direction. The square stem should be rotated 90 degrees.
Rotate the square stem counterclockwise 90 degrees once the pressure has been released from the lift cylinder circuit.Refer to this Operation and Maintenance Manual, "Equipment Lowering with Engine Stopped" for additional information.Tilt Cylinder Circuit
Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact skin.