TRANSFORMER AS 2835270 - Caterpillar

All 3406, 3406B EnginesDescription of Change: A new cylinder head gasket is used on 3406B engines. The new gasket is coated with a single layer of silicone material on the cylinder head side and a single layer of black Teflon® material (PTFE) on the spacer plate side of the gasket. The silicone material limits adhesion to the cylinder head. The PTFE material prevents adhesion to the aluminum spacer plate.Adaptable To: The new 9Y7786 Cylinder Head Gasket replaces the former 2W7983 Cylinder Head Gasket, which was coated with a double layer of orange Teflon® material (PTFE) on both sides. The 9Y7786 Gasket is in effect on the following 3406B Engines. Truck Engines 4MG32240-Up, 8TC5331-Up
Industrial Engine 6TB5101-Up
Marine Engine 4TB1781-Up
Generator Set Engines 2WB6300-Up, 4RG199-Up
Vehicular Engine 70V28121-Up
The former 2W7983 Gasket (orange colored) can be adapted to simulate the 9Y7786 Gasket by removing the double layer of PTFE material from the cylinder head mounting surface of the gasket. This can be accomplished with a clean Scotch Brite® cleaning pad and/or xylene solvent.
Cleaning Procedures
Thoroughly remove the PTFE material residue from the cylinder head bottom deck and the spacer plate during rebuild by using either method listed in the previous paragraph. This material has a tendency to stick to the head gasket mating surfaces during operation and should be removed to help eliminate future parts slippage.
Surface Inspection
Inspect the bottom deck of the cylinder head for flatness according to the Service Manual and repair if necessary.
Check the top deck of the cylinder block for flatness. Inspect for liner beat-in or erosion under the liner flange and repair with an insert. The block deck may require machining if the engine was operated extensively after a head gasket failure.
Liner Projection
Make sure liner projection is within specification during rebuild before installing new 9Y7786 Gaskets or reworked 2W7983 Gaskets. DO NOT USE 2W7983 Gaskets in repairs unless they are reworked.
On engines with aluminum spacer plates, use care in obtaining liner projection measurements to prevent marring the surface. To prevent damage to the spacer plate, use copper washers instead of hardened steel washers with the spacer plate bolts. Do not excessively tighten the spacer plate bolts.
In addition, to increase the accuracy of liner projection measurements and also prevent damage, cut "figure 8" sections from an old spacer plate and install them under the spacer plate bolts. These are the center ribs between the cylinder holes from a scrapped 2W8601 Spacer Plate as shown in the illustration. The top and bottom radii of the "figure 8" section should coincide with the radii of the washers. Refer to the Service Manual procedure in conjunction with use of the "figure 8" sections.
Rework old spacer plate to fabricate "figure 8" sections.Aluminum Spacer Plate Reusability
The 3406 Engine uses a die cast aluminum spacer plate which weighs and costs less than the steel spacer plate which is no longer available. The aluminum spacer plate requires more care in handling and cleaning to prevent damage and retain reusability than the former steel spacer plate. Do not use a