Usage:
3406B And 3406C (8TC, 3ZJ, 5KJ, 2EK, 4CK) Truck Engines
Description of Change: This article supersedes the article with the same title on Page 7 of the January 1994 issue of Truck Engine News.
Changes have been made to some of the fuel injection pump components to provide improved high pressure sealing. These changes include a new bushing, bonnet, and plunger and barrel assembly.
The new bushing has a wider load ring for improved torque retention. The tightening torque for the new bushing is 258 N·m (190 lb ft). Double torquing is recommended with the new bushing. If the bushings are reused, they should be installed in the same bores they were removed from.
The bonnet has two rings. The new bonnet has the outer load ring moved further outward, away from the inner sealing ring. This will increase the load applied to the inner sealing ring. The increased load will result in better sealing. It is recommended to use the new wide load ring bushings when installing the new bonnet.
The barrel in the new plunger and barrel assembly is made from different steel with a different heat treatment process. This results in reduced crack sensitivity. The new bonnet is also made from this same steel for reduced crack sensitivity.
Location of wider bushing load ring (A), and bonnet inner sealing ring (B) and new outer load ring (C).
Adaptable To: The new fuel injection pump components are the 113-7794 Bushing, 108-2102 Bonnet, and 108-2104 Plunger And Barrel Assembly. The new bonnet, and plunger and barrel assembly are part of the new 108-6634 Fuel Injection Pump Group. The new 108-6634 Fuel Injection Pump Group is used in some 3406C Truck Engines. The new 108-6633 Fuel Injection Pump Group is used in some 3406B and some 3406C Truck Engines. The new and former components are identified in Chart A. The new components are in effect as shown in Chart B. The new components are adaptable to the engines identified in Chart C.
