SEAL-O-RING 6V5554 - Caterpillar

Coolant System
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, turn off the engine. Allow the cooling system pressure cap to cool. 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.This is because of the following differences:
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 ten minutes. Do not loosen the high pressure fuel lines in order to remove air pressure from the fuel system.Engine Oil
To relieve pressure from the lubricating system, turn off the engine.