ROD-ADJUSTMENT 7E6879 - Caterpillar

3406B And 3406C Engines Equipped With Center-Mounted Turbocharger And Dry-Type Exhaust ManifoldsIntroduction
This instruction lists the procedures, tools, parts, and machining dimensions in order to modify the exhaust manifold.The modification consists of drilling mounting holes to a larger diameter and slotting (elongating) mounting holes. This process will provide increased clearance between the exhaust manifold components and the mounting studs in order to allow for thermal expansion.The increased clearance will reduce exhaust manifold mounting stud breakage.The exhaust manifold modification approximates the design of exhaust manifolds in current production. The suspect manifold should be inspected to ensure that it has not been modified or is not the previous design which can be later modified. A portion of the modification requires precision machining and some component replacement. Machine ONLY as referenced in the drawings and replace components with the part number(s) shown, NOT as referenced in other publications.Modifying Exhaust Manifold Group
Remove Turbocharger And Exhaust Manifold
1. Refer to the Service Manual to remove the turbocharger and exhaust manifold.2. The exhaust manifold, after removal from the cylinder head, must be separated at the center section's slip joints.If the slip joints need to be heated in order to separate them, use a gas heating tip to heat the sections. Remove all mating slip joints while they are still hot.Cleaning And Inspection
All exhaust components must be thoroughly cleaned and inspected. Glass beading is recommended for cleaning the exhaust components.3. Clean the interior and exterior of the slip joints. Clean the manifold flanges at the manifold gasket surfaces.Remove any flaking from the interior of the manifold sections; particularly at the divider wall of the turbocharger mounting flange.4. Inspect all exhaust components for serviceability. Replace any suspect or damaged parts with new parts. There are different cast iron alloys used in the center section and manifold ends. If the manifold sections are to be replaced, the part numbers must be the same. The part numgers are cast on the manifold.5. Remove any broken mounting studs from the cylinder head. Current production engines use 106-1792 Taperlock Studs and 108-3612 Spacers.Clean and inspect the remaining mounting studs in the cylinder head. Remove and discard any suspect or damaged studs.6. Clean the cylinder head at the manifold gasket surfaces.7. Clean (chase) the internal threads (for the mounting studs) in the cylinder head with 4C-4993 Tap (Taper). The cleaning (chasing) should be performed with a hand-held tap holder. The mounting studs threads are a taper lock dimension and should ONLY be cleaned (chased) with 4C-4993 Tap (Taper) to the original depth.For exhaust manifold center sections, other than 4W-4384 and 9L-5848 Exhaust Manifolds for mid-mount turbochargers, 4S-6137 Taperlock Stud and 2S-3770 Spacer should be used in place of 6L-8562 Taperlock Stud at number 3 cylinder.The 4S-6137 Taperlock Stud is longer than 6L-8562 Taperlock Stud. Because of this interference the stud can not be used at this location with 4W-4384 and 9L-5848 Exhaust Manifolds.8. Coat the threads of new 4S-6137 Taperlock Studs with 5P-3931 Thread Compound. Install 4S-6137 Taperlock Studs and tighten to a