Usage:
3406, 3408 Truck Engines
- SUPPLEMENT: 01/00/91
Truck Engine News, February 1990, Page 3, "New Exhaust Manifold Studs Available." Disregard this article and see the article "Update Information For Exhaust Manifolds" in this issue.
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The exhaust manifold studs may fail due to exhaust manifold movement. The studs are more likely to fail in extreme conditions such as high altitude and high exhaust manifold temperatures.
The new 9X2840 Stud can be used to replace the former 6V5699 Stud. The 8M2296 Stainless Steel Nut should be used with the new stud.
The following procedure can be used to retain the exhaust manifolds and at the same time allow for manifold movement to help prevent stud failure.
1. Remove the manifolds from the engine. Do NOT separate the exhaust manifold sections as outlined in the above reference articles.
2. Replace any broken studs with the new 9X2840 Stud.
3. Use a suitable method (such as an end mill) to elongate the existing holes as shown in Illustrations 1 and 2. The dimension for the slot are shown in Illustration 3.
NOTE: If the machine is being repaired in the field and an end mill is not available, the same holes shown in Illustration 1 and 2 can be increased to 12.7 mm (.50 ") using a reamer.
Illustration 1. Exhaust manifold for 3406 Engine.
Illustration 2. Exhaust manifold for 3408 Engine.
Illustration 3. Dimensions for slots.
4. Install the exhaust manifolds using new 9Y4582 Manifold Gaskets.