1978/03/06 Caterpillar

Stronger Piston And Connecting Rod Are Tapered In Area Of Piston Pin{1213,1214,1218}

Usage:

3400 Series Engines (Direct Injection)

Description of Change: The connecting rods and pistons now used in 3400 Series Engines with direct injection are of a different design. As shown in the first illustration, the sides of the new connecting rod and the inner part of the new piston in the area of the piston pin bore are tapered. As shown in the second illustration, the sides of the former connecting rod and the inner parts of the former piston were straight. Also, the top edge of the crater is changed in the new piston.

The new piston is stronger than the former piston for two reasons. More of the piston pin is in the bore of the new piston. This causes a distribution of the stress in the piston pin bore over a larger area. Second, the material in the new piston is stronger than the material in the former piston.

The design of the crater in the new pistons gives better combustion of the fuel.

Illustration 1.

Illustration 2.

Adaptable To: The new parts are adaptable to earlier engines when used together but a complete set of new pistons and connecting rods must be installed. On 3406 Truck Engines with direct injection, the fuel ratio control must be set at +.035" (0.89 mm) when the new pistons are installed. Since the new pistons and connecting rods do not have the same weight as the former pistons and connecting rods, the new and former parts must not be mixed in an engine. If the new and former parts are used together in an engine, the result is added stress and vibration in the engine.

Caterpillar Information System:

1978/02/27 New Tachometer Drive Adapter Assembly Prevents Failure Of The Seals For the Tachometer Drive Group And Transfer Pump{7462,1256}

1978/02/27 Modification Of Oil Pan For Installation Of Oil Sump Heater{1302}

1978/02/27 Improved Fuel Priming Pump Assembly Has Better Sealing Characteristics; Repair Kit Available For Knob{1258}

1978/02/27 Stronger Exhaust Manifold Gasket Now Used{1059}

1978/02/27 Replacement Seals And Wear Sleeves Now Available As A Crankshaft Seal Kit{1202,1160,1161}

1978/02/27 Fabricated Adapters Permit Horizontal Mounting Of Transmissions On 1P2420 Transmission Repair Stand{0640}

1978/02/27 New Seal Assembly With Longer Ferrule Prevents Damage To Ferrule During Cylinder Head Installation{1100,1101,1300}

1978/02/13 Complete Set Of Contact Points For Dial Indicators Is Now Available In One Group{0653}

1978/02/13 Replacement Seal Group For Water Pump Impeller Now Has All The Seal Parts Plus An Installation Tool{1361,0622}

1978/02/06 Probable Causes Of Low Fuel Delivery During Testing On Fuel Injection Test Benches{0650,1250}

1978/02/06 New Water Temperature Regulator Opens At 180°F (82°C){1350,1355,7304}

1978/02/06 Attachment Groups Put Corrosion Inhibitor Directly Into Cooling System{1350}

1978/03/06 5P8558 Pressure Gauge Calibrating Group Checks Pressure Gauges{0650}

1978/03/06 Use Again Specifications For Valve Springs Are Changed{1108}

1978/03/06 New Starter Motors Have Solenoid On Top Of Starter{1407,1453}

1978/03/13 5P8687 Tee Test Tooling Group{0651,5050}

1978/03/13 When A 6N5906 Hour Meter Will Not Operate Correctly, Check The Electrical Supply Before A Replacement Hour Meter Is Installed{7480,1400}

1978/03/13 Soft Washers And Lockwashers Are Now Used With The Mounting Bolts For Air-Fuel Ratio Control{1278,1264}

1978/03/13 The Causes And Reduction Of White Exhaust Smoke During Cold Engine Starts; Maintenance Aids Available To Decrease This Problem{1250,1383,1050}

1978/03/20 "Danger Do Not Operate" Tags Now Available{0374}

1978/03/27 Use 5P8706 Die Repair Kit For The Repair Of 9S6331 Die Assembly{0623}

1978/03/27 5P8675 Extension Handle Available For General Uses{0614}

1978/03/27 Improved Thrust Washers Now Used With Planet Gears{3000,3072,3106,3110,3003,3001,3100,3116,3159,3176,3107,5150,5165}

1978/03/27 9N3700 Or 9N3299 Nozzle Assemblies Must Be Used On 3208 Engines That Are Equipped With Exhaust Gas Recirculation (EGR){1254}