CHAMBER ASSEM. 2S8957 - Caterpillar

D399 (91B) Marine Engines, G399 (49C) Industrial EngineSUPPLEMENT: 04/06/92SERVICE MAGAZINE; October 7, 1985; Page 3; "New Water Cooled Exhaust Manifolds Available; Existing Water Cooled Exhaust Manifolds Can Be Strengthened Or Salvaged" for D399 (91B) Marine Engines, G399 (49C) Industrial Engine.The weld instructions on Illustration 3 are not correct. The correct Illustration 3 follows:
--------------- END SUPPLEMENT ---------------Description of Change: New water cooled exhaust manifolds are available for D399 Marine Engines and G399 Industrial Engines. The new exhaust manifolds are stronger and more resistant to cracking than the former exhaust manifolds. Former exhaust manifolds can be salvaged or strengthened by rewelding and adding a plate and gussets. The plate and gussets reduce flexing which can cause cracks to develop and allow the manifolds to leak.
Adaptable To: The new water cooled exhaust manifolds are direct replacements for the former water cooled exhaust manifolds. See the chart and the note. When installing a new or a reworked water cooled exhaust manifold it may be necessary to grind part of the flashing off the cylinder head between the exhaust ports. This will only be necessary on some engines.Former 3N5805 and 3N5806 Water Cooled Exhaust Manifolds can be salvaged or strengthened by rewelding old welds and adding one 7W9157 Plate and 14-7W9158 Gussets to each manifold. The procedure to reweld and add the plate and gussets to the manifolds is as follows.
1. Remove the weld from the top and 25 mm (1.0") around the corners of each exhaust mounting flange. Use an air carbon arc torch or similar tool to remove the weld. See Illustration 1.2. Reweld the exhaust mounting flanges. Stress relieve all welds as they are completed by striking them with a large hammer.
Illustration 1. Reweld exhaust mounting flanges.3. Remove the material around any cracks or leak sources and reweld them. Stress relieve the welds.4. Mark the location of the 14-7W9158 Gussets on the manifold. See Illustration 2.
Illustration 2. Location of 7W9158 Gussets.5. Make sure the manifold is clean and free of weld splatter where the gussets are to be welded on. Weld the 14 gussets in position on the manifold as shown in Illustration 3. Weld the gussets on one side only.
Illustration 3. Weld 14-7W9158 Gussets to the manifold.6. Clean and mark the areas of the 7W9157 Plates that are to be welded. See Illustration 4.7. Clean the manifold and put the 7W9157 Plate in position on it. Position the plate so its ends are in alignment with the centerlines of the bolt holes in the exhaust mounting flanges. Also, put the bend in the plate even with the bend in the exhaust manifold. See Illustration 4.8. When the plate is in the correct location, make a weld at the middle of the top side and at each end of the plate to hold it in position. Complete only the welds on the top side of the plate. Stagger the welds to reduce heat build-up and warpage. Stress relieve the welds.
Illustration 4. Locate and weld 7W9157 Plate to manifold.9. Start