ELBOW 2304518 - Caterpillar

1693 Truck EnginesA process change has been made to the 8F4225 Bolt used in the cylinder heads on the above machines. Formerly the bolt was available only in phosphate and oil coating (black color). Now it is available only with zinc dichromate plating (yellow metallic color). This change became effective in January of 1988. Care must be taken when making cylinder head repairs that require new cylinder head bolts and/or washers. The new zinc plated cylinder head bolts should be used only with 8T4994 zinc plated washers. If the former 8F4225 Bolts (phosphorus and oil treated) are reused, use the 5P8248 phosphorus and oil treated washers. Phosphorus and oil treated cylinder head bolts should not be used with zinc plated washers. Combining bolts and washers with different finishes results in the cylinder head bolts being over-tensioned when tightened to the specified torque. Use bolts and washers only in matched sets with a similar type of finish.
Hardware of different types can be used in combination on the same cylinder head, but care must be taken to use bolts only with washers of a similar finish. Torque specifications are the same for both finishes on bolts of similar size.