DISC FRICTIO 6Y7933 - Caterpillar

Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.
Evacuate as much fuel and oil as possible from the cylinder head before installing the unit injector. Several evacuations may be necessary. Use Tooling (G) to remove the fuel and oil from the cylinder head.Note: Tooling (L) is available to clean loose material from the sleeve bore and the cylinder.
Inspect the unit injector sleeve for damage and carbon deposits.
Clean the carbon from the sleeve, the sleeve bore, and the end of the unit injector, if the unit injector is being reused. Clean the carbon from the seat area that is inside of the cylinder head. A fine grade of Scotch Brite material is preferred. Use Tooling (H) to clean the bore of the unit injector tip. Use the Surface Reconditioning Pad in order to clean the carbon in the cylinder head. Use Tooling (J) in order to remove the carbon from the surface of the sleeve.Note: Using power tools in order to rotate the material should not be necessary. The carbon in the sleeve is more removable than the carbon at locations that are exposed to higher temperatures.The following procedure is the preferred method of cleaning the sleeve bore.Place a 38 mm (1.5 inch) square piece of Scotch Brite material on the end of Tooling (K) . Twist Tooling (K) with Tooling (M) against the lower surface of the sleeve bore.The surface should be cleaned until the surface is smooth and shiny. The entire sleeve bore should be cleaned in order to remove any loose carbon particles.Note: Tooling (J) is available to clean loose material from the sleeve bore and the cylinder.
The correct procedures and tooling specifications must always be used. Failure to follow any of the procedures may result in damage, malfunction, or possible engine failure.
Note: New seals should be installed after each removal of the unit injector from the engine. To order O-ring seals for the unit injector, refer to the Parts Manual.
The O-ring seals and the backup rings must be installed in the correct orientation. Damaged seals will result in excessive oil consumption or excessive leakage under the valve cover. Use care to prevent nicks or damage to the seals.
Illustration 1 g01137291
Lubricate O-ring seals (6) , (7) , and (8) and the sleeve bore of the unit injector sparingly with clean engine oil.
Use Tooling (E) and Tooling (F) to install the backup rings (4) and (5) first. Install O-ring seal (6) .
Use Tooling (E) and Tooling (F) to install backup ring (9) . Install O-ring seal (8) .
Install O-ring seal (7) .
Lubricate the O-ring seals and the backup rings on unit injector (1) with clean engine oil before installation.Note: Proper installation of the unit injector is important. Damage to the upper high-pressure seals can cause excessive oil leakage under the valve cover. This may cause the engine not to start due to a low actuation pressure. Damage to the lower high-pressure seals may allow high-pressure oil to leak into the fuel supply passage.