CONTACTOR-TEMPERATURE 4W2640 - Caterpillar

(6TB, 90U) Industrial, 3406C (4TB) Marine, 3406C (2WB, 4RG, 4JK) Generator Set EnginesReference: Engine News, July 1993, Page 3,; "New Exhaust Manifold End And Center Sections Used In Dry Type Exhaust Manifold Groups". Description of Change: Longer studs and spacers are used in the cylinder head groups and exhaust manifold groups. The longer studs provide increased durability and are more resistant to bending fatigue. The 106-1792 Stud is 100.0 mm (3.94 in) long, the former 4S-6137 Stud is 81.0 mm (3.19 in) long. The 108-3612 Spacer is 53.0 mm (2.07 in) long, the former 2S-3770 Spacer is 33.5 mm (1.32 in) long.
Adaptable To: The longer studs and spacers are identified in the chart. For engines with "Dry" Exhaust Manifold Groups, the longer studs and spacers are in effect with: 3406C Industrial Engines 6TB12219, and 90U199623406C Generator Set Engines 2WB13862, 4RG1964, and 4JK109The longer studs and spacers can be used in earlier 3406 Engines. The studs are part of the cylinder head group and the spacers are part of the manifold group.
A 9U-7224 Manifold Installation Guide is available to align the manifold studs in the center of the slotted and oversize manifold holes during installation of the exhaust manifold group. Three 9U-7224 Manifold Installation Guides are required for installation of the manifold.Tighten the retaining nuts for "dry" exhaust manifolds in the sequence shown in Illustration 1 to a torque of 38 5 N m (28 4 lb ft).
Illustration 1. Tightening sequence for manifold retaining nuts on "dry" exhaust manifolds."Water Cooled" Exhaust Manifold Groups
The same components identified in the chart are used with the "Water Cooled" Exhaust Manifold Groups effective with 3406C Marine Engine 4TB4138.
Tighten the retaining nuts for "water cooled" exhaust manifolds in the sequence shown in Illustration 2 to a torque of 38 5 N m (28 4 lb ft).
Illustration 2. Tightening sequence for manifold retaining nuts on "water cooled" exhaust manifolds.