Usage:
3406, 3406B Truck Engines
Reference: Truck Engine News, November 1988, Page 1, "New Liner Seat Insert Available" for 3400 Family of Engines equipped with spacer plates. Truck Engine News, January 1989, Page 1, "New Head Gasket Available (Used); Head Gasket Replacement Guidelines" for 3406 Family of Truck Engines.
Description of Change: A new 7E6000 Cylinder Head Gasket is used on all 3406B Truck Engines. The new gasket has the following improvements over the former gaskets.
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- ... 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.
- ... The rear and front edges of the gasket body are filled with gasket material between the bolt holes to give more support to the fire rings at both ends of the gasket. See illustration.
- ... 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.
Locations of the filled-in ends on the new 7E6000 Gasket and on the temporary parts service 7E3240 Gasket.
NOTE: The added material shown at both ends also makes it possible to identify from the outside of the engine the new 7E6000 Gaskets from the former 2W7983 or 9Y7786 Gaskets. (A parts service only 7E3240 Gasket also had both ends filled in.)
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- ... This gasket is NOT coated on the cylinder head side. It DOES have a single layer of black (PTFE) on the spacer plate side. The PTFE pre vents sticking to the aluminum spacer plate.
Adaptable To: The gasket is effective with the following truck engine serial numbers.
- 3406B Truck Engine: 4MG62277
- 3406 Truck Engine: 92U66443
- 3406B (PEEC) Truck Engine: 8TC8519
- 3406 Truck Engine: 92U66443
This new 7E6000 Gasket can be installed in place of the former 2W7983, 9Y7786, or 7E3240 Gaskets which are all canceled. For your information, a summary of their use on truck engines and the features of these four gaskets are in the chart.
Any time the new head gasket is to be installed, refer to the following topics so that maximum life can be obtained from the new gasket, head, block, spacer plate, 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 (.001 to .006"). 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 Manuals for these engines.
Wear or erosion under the liner flange will require use of a stainless steel insert. Read the reference article about the new liner seat insert. The head and/or block surfaces may have been damaged if the engine was operated extensively after a head gasket failure.
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To prevent entry of debris into the engine when cleaning excess Teflon from the block and head, use a clean Scotchbrite® pad only. Read the second reference article which gives additional guidelines on cleaning, inspection, and repair considerations. Be careful with a rotary pad to be sure the flatness of the block and/or head is not changed.
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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 425.02 mm (16.733 "), and is also in the Service Manuals. 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 111.51 mm (4.390"), and limits the amount of material that can be taken off the bottom of the head.
Retightening Of Head Bolts
After installing the new 7E6000 Gasket, or the temporary parts service 7E3240 Gasket, retightening the head after a road test or dynamometer test, or at the first scheduled check for valve lash is not necessary. See previous chart. The thicker fire ring and the reduced fire ring wrap increase the combustion seal and gasket body loading, which reduces the need for subsequent retightening. Remember, either of these gaskets can be identified on the engine by the filled-in ends as shown.
Engines using the later 2W9783 Gasket and all engines using the 9Y7786 Gasket should have the head bolts retightened. See chart for engine serial numbers. These two gaskets have no asbestos, and they use the standard thickness fire ring and wrap.
The cylinder head bolt torque, regardless of whether tightened only once or retightened, is 450 ± 20 N·m (330 ± 15 lb ft). Follow the bolt tightening sequence in the Service Manuals, and tighten in three or four steps to ensure uniform loading.