1977/09/19 Caterpillar

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

Usage:

3400 Series Engines Equipped with Precombustion Chambers

Description of Change: The connecting rods and pistons now used in 3400 Series Engines equipped with precombustion chambers are a different design. See the Illustrations. As shown in the first Illustration, the sides of the new connecting rod around the piston pin bore are tapered. The inner part of the new piston is also tapered in the area of the piston pin bore. As shown in the second Illustration, the sides of the former connecting rod and the inner parts of the former piston were straight.

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.

Adaptable To: When used together, the new parts are adaptable to earlier engines as shown in the chart but a complete set of new pistons and connecting rods must be 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 cannot be used together 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.

New connecting rod and piston with tapered joint.

Former connecting rod and piston with straight joint.

Caterpillar Information System:

1977/09/19 Use Viscous (Fluid) Type Crankshaft Vibration Damper In Place Of Rubber Type Damper{1205}

1977/09/19 Changes To The Injection Pump And The Fuel Setting{1251,1257}

1977/09/12 New Refrigerant Compressors And Kits With Improved Seals; Conversion Of Earlier Units{7320}

1977/09/12 The Discrepancy Card Has Changed{0374}

1977/09/05 Field Repair Of Cooler Cores Made Of Aluminium{1063,1374,1375}

1977/09/05 Check For Extra Holes In Crankshaft Flange If Oil Leaks From Between The Flywheel And Crankshaft Flange{1156,1202}

1977/09/05 Installation Procedure For Crankshaft Wear Sleeves Changed{1202,1160,1161}

1977/08/29 More Bolts Hold Flywheel Housing Group{1157,1162}

1977/08/29 Anti-Corrosion And Break-In Coatings{0374,3256}

1977/08/29 Engine Valve Springs Are Now Made Of Stronger Steel{1108}

1977/08/29 New Tube Assemblies For Turbocharger Oil Lines; New Base Assemblies For Oil Filters{1052,1306,1307}

1977/08/29 Improved Cylinder Block With Spacer Plates Used With Improved Cylinder Heads And Cylinder Head Gaskets{1101,1201,1221}

1977/09/26 Use Correct Contact Point With Dial Indicator To Be Sure Of The Accuracy Of The Measurements Of Fuel Setting And Fuel Ratio Control Setting On Sleeve Metering Fuel Systems{0653,1250}

1977/09/26 Stronger Fan Drive Pulley Prevents Cracks During Assembly; Torque On Pulley Bolts Changed{1359}

1977/09/26 New Special Instruction Gives General Information On The Use Of The 5P6590 Wiring Harness Tester For Electrical System Testing{0650,1400}

1977/10/03 Change Is Made to Support Beam For Front Of Engine{0643}

1977/10/03 Turbocharger Heat Shields Are Stronger{1073}

1977/10/03 Washer Removed From Variable Timing Unit{1206,1272}

1977/10/03 Do Not Use Plastic Tubing With Brass Couplings As A Fuel Supply Line{1274}

1977/10/10 Be Sure To Drain Oil From The BrakeSaver At Every Lubricating Oil Change Period{1318,1155}

1977/10/10 Fuel Transfer Pump Shaft With Chromium Plate{1256}

1977/10/10 New Front Housing Has Stronger Boss For Alternator{1151}

1977/10/10 Troubleshooting The Tachometer System Of The 4S6553 Engine Instrument Group{0651}

1977/10/10 Use Only The Larger Size Inserts To Make A Repair To Cylinder Block Counterbores For Cylinder Liners{1201,1216,1217}