Usage:
All 3406 Truck Engines
Head Gasket
The former 7E6000 Cylinder Head Gasket has been replaced by the new 6I3066 Cylinder Head Gasket. This new gasket features a graphite body for added heat resistance. The body material will resist extrusion and provide better oil sealing capability. It can withstand occasional exhaust gas seepage past the fire ring better than the previous material. This body design results in a more flexible gasket that requires extra care in handling and storage.
Gasket body performance is maximized when assembled with clean, dry components. It is important to thoroughly clean the cylinder head bottom deck, liner flanges, and spacer plate with component cleaner or alcohol prior to gasket installation.
The fire ring material has changed from mild steel to stainless steel to provide improved combustion sealing. The wrap material remains stainless steel and retains its tab style retention method to the body material. One benefit of the new gasket design is a decrease in sensitivity to liner projection that is low in the specified range. Another benefit is the stainless steel fire ring in the 6I3066 Gasket is less prone to deformation through thermal cycling than the previous head gasket. More load is retained on the fire ring, thus reducing exhaust gas leakage. The retorquing of cylinder head bolts DOES NOT improve the performance of this gasket. See the chart for effective serial numbers.
Spacer Plate
The former 2W8601 Aluminum Spacer Plate (standard thickness) has been replaced by the new 6I2981 SteelSpacer Plate. The new plate provides added durability and reusability when compared to the former plate. Both plates are functionally interchangeable. A wider selection of cleaning methods can be used with the steel plates than with the aluminum plates to simplify repair. The former 6I3189 Aluminum Spacer Plate [0.08 mm (.003 in) thinner than standard] is replaced by the new 6I4303 Steel Spacer Plate [0.08 mm (.003 in) thinner than standard]. See the chart for effective serial numbers.
Head Bolts
New 12 point head bolts are used to secure the head to block joint. The new 9X8904 Bolts (which require a 3/4 inch, 12 point socket) are now used in place of the former 2H3750 Standard Hex Head Bolts (which require a 1 1/8 inch 6 or 12 point socket). The rocker arm support bolts/studs remain unchanged. The new bolts provide better reusability due to an improvement in yield strength over the former bolt. The two bolts are functionally interchangeable and can be mixed within the same engine.
Prior to final assembly, lubricate all the head bolt threads, washers and bottom of bolt heads with a thin coat of 6V4876 Molykote Paste. Use of this friction reducing paste will significantly improve the load on the gasket.
Spacer Plate Gasket
The new 6I4024 Spacer Plate Gasket replaces the former 7C3037 Gasket. The new gasket has a profile that matches the bottom of the cylinder head for improved fluid sealing ability. The new gasket retains the latex coating on the surface adjacent to the cylinder block.
Liner Projection
The liner projection specifications have not changed. See the appropriate Specifications Module.
An alternate method of obtaining liner projection measurements follows. See illustration. After assembly of cylinder liners (7), spacer plate gasket (5) and spacer plate (4), secure both the plate and liners with the hardware shown in Illustration 1. The use of this hardware allows both the liner flange and spacer plate to be secured simultaneously without damaging the aluminum spacer plate. Use six 7H3598 Bolts (1), 8F1484 Washers (2) and 7K1977 Fiber Washers per cylinder for consistent clamping load (26 bolts and 26 of each washer total across the engine). This method alleviates the need for the "H" bar to hold down liners during projection measurements. Tighten bolts (1) evenly in 4 steps up to a maximum of 95 N ·m (70 lb ft). Use the 8T0455 Liner Projection Tool Group to obtain four measurements on each liner flange.
Illustration 1. Location of components for liner projection measurement.
In some cases, the latex bead on the bottom of the spacer plate gasket may not fully compress and could affect readings on the exhaust manifold side and ends of the spacer plate. Measurements can be taken elsewhere on the liner flange to minimize this effect.
Besides the allowable range for the entire set of liners 0.03 to 0.15 mm (.001 to .006 in), the maximum differential between high and low measurements made at 4 places around each liner is 0.05 mm (.002 in). The average projection of liners next to each other must not be more than 0.05 mm (.002 in). The maximum difference of all average measurements of all liners must not exceed 0.10 mm (.004 in).
Although the 6I3066 Cylinder Head Gasket is designed to seal the head to block joint throughout the allowable liner projection range, the optimum projection for the maximum sealability of both exhaust gas and fluids is 0.090 mm (.0035 in).