Usage:
Description of Change: A new cylinder head gasket is used on all 3306B Truck Engines. It has the following improvements over the former gaskets.
... A thicker fire ring to compensate for the asbestos-free body material. The thicker fire ring and thinner wrap help to prevent leakage of combustion gases, and give a better "crush" on the liner flange when the head is tightened.
... The overlap of the stainless steel fire ring wrap is reduced to give better gasket body loading and minimize the possibility of fluid leaks. The wrap has a tab-style design. This tab design results in a more flexible gasket that requires extra care in handling and storage.
... Apply 6V4876 Molykote Paste Lubricant on the cylinder head bolt threads, bolt head and washer. This increases head bolt load by 15%.
Adaptable To: The new 7E6167 Cylinder Head Gasket is a direct replacement for the former 7N7999 Cylinder Head Gasket which has been canceled. The gasket is effective with the 3306B Truck Engine 63Z18237.
Any time the new head gasket is to be installed, refer to the following topic so that maximum life can be obtained from the new gasket, head, and engine block.
Liner Projection And Machining The Block And/Or Head
Do NOT adjust the liner projection above the block if it measures in the range of 0.03 to 0.15 mm (.0013 to .0069"). ALSO, make sure that the differences between all four measurements at any one cylinder do not exceed 0.05 mm (.002"). AND, the difference between the average projection of two liners next to each other must not exceed 0.05 mm (.002"). These specifications are in the Service Manual for these engines.
Wear or erosion under the liner flange will require use of a stainless steel insert. Refer to the Service Manual for available shims. The head and/or block surfaces may have been damaged if the engine was operated extensively after a head gasket failure.
The maximum amount of material that can be machined from the top deck of the block is controlled by the minimum dimension from the crankshaft centerline to the top deck on the block. This minimum is 383.10 mm (15.083"), and is also in the Guideline for Reusable Parts SEBF8076. Use the 6V7840 Deck Checking Tool Group to measure this dimension. Special Instruction SEHS8187 explains the use of this device.
There is also a minimum allowable thickness for the head. This is 98.89 mm (3.893"), and limits the amount of material that can be taken off the bottom of the head.
The cylinder head bolt torque is 250 ± 17 N·m (185 ± 13 lb ft). Follow the bolt tightening sequence in the Service Manual, and tighten in three or four steps to ensure uniform loading.