Usage:
3406B Truck Engines ( 7FB35917-Up ) Equipped With Air-To-Air Aftercoolers (ATAAC)
Description of Change: Changes have been made to the air lines groups on the above engines. Earlier engines had one S509 Bolt in the inlet flange of the turbocharger to hold the inlet elbow in place. A change was then made to add another S509 Bolt in the inlet flange. In both cases, the S509 Bolt was too short and could cause the threads to strip out of the flange.
The S1594 Bolts are now being used in place of the former S509 Bolts. The S1594 Bolt is longer and will prevent the threads from being stripped out of the inlet flange of the turbocharger.
Adaptable To: The use of the S1594 Bolt is in effect with 3406B Truck Engine 7FB51972 in the 7C94, 7W3885, 7W8996 and 7W9031 Air Lines Groups.
On earlier engines, replace the former S509 Bolt(s) with the S1594 Bolt(s). If the threads are stripped out of the inlet flange, there are two methods that can be used to correct the problem.
1. Use a Heli-coil to repair the damaged threads. Install the S1594 Bolt(s).
2. Drill the damaged threads completely out. Install a 3B1915 Bolt(s) upside down with a 1D4717 Nut on the end of each bolt. Some grinding of the bolt head(s) may be necessary to eliminate interference with the compressor housing.