1977/10/24 Caterpillar

New Piston Group Has Improved Iron Band In The Piston Body{1214}

Usage:

1693 Truck Engines

Description of Change: A new piston group is used in 1693 Truck Engines. The new group uses a piston body with an improved cast iron band for the keystone type piston rings. The location of the band in the piston body is the same as in the former 9L6054 Piston Group, but the shape of the band is changed from taper sides to flat sides for increased strength. At the same time, a change in core design makes the piston stronger around the top (crown area).

Adaptable As: Direct replacement. The new 9N2875 Piston Group (Basic) is a direct replacement for the former 9L6054 Piston Group (Basic) which is canceled. The 4N5619 Piston Ring Group (Replacement) is not changed.

NOTE: The new piston is a little heavier than the former piston. The difference in weight is not enough to cause engine damage, but it can possibly cause a small increase in vibration if the new and former pistons are mixed in the same engine.

In addition to the use of the new 9N2875 Piston Group for replacement of the 9L6054 Piston Group, the new group can be used for replacement of the earlier 1P435, 9S2266, 7N738 and 7N739 Piston Groups in all 1693 Engines. All of these earlier pistons had rectangular (square) type piston rings (in comparison with the improved keystone type rings), and installation of the later design pistons and rings will give longer service life. The recommendation is that the 7N738 and 7N739 Piston Groups not be installed for service replacement.

Caterpillar Information System:

1977/10/24 Adjust Shop Tire Pressures For Operation In Cold Temperatures{4203,4204}

1977/10/24 Assembly Procedure For The 5P4721 Tube (Part Of The 5P4149 Conversion Group And 5P4150 Nozzle Testing Group){0650}

1977/10/17 Vent Tube Added To Jacket Water Aftercooler{1063}

1977/10/17 Separate Parts Of Oil Pump Cover Now Available{1304,1314}

1977/10/17 Improved Main, Thrust And Connecting Rod Bearings Have Aluminum Alloy With More Strength{1230}

1977/10/17 Preparation Of Truck Engines For Cold Weather Operation{1300,1000}

1977/10/17 Fabricated Extension Prevents Fuel "Splash" During Injection Valve Testing{0650,1254}

1977/10/10 If The Fuel Setting Dimension Is More Than 7.00 MM, Remove The End Play Of The Camshaft To Make The Fuel Setting{1257,1286}

1977/10/10 Improved Oversize And Undersize Connecting Rod And Main Bearings With Higher Strength Aluminum Alloy{1203,1219,1230}

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

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

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

1977/10/24 Replacement Bearings Have Aluminum Alloy With More Strength{1203,1213,1230}

1977/10/31 New Hydraulic Flow Meter Has Many Improvements To Make It Easier, Faster And Safer To Use Than The Former Flow Meter{0651,5050}

1977/10/31 New Governor Spring Changes Speed Regulation{1264,1286}

1977/10/31 With New 5P7448 Adapter, Earlier Fuel Injection Valves And Nozzles Can Be Tested And Adjusted On The 5P4150 Nozzle Testing Group{0651,1254}

1977/10/31 Some Wobble Is Acceptable In Rubber Vibration Dampers For Crankshafts{1205}

1977/11/07 Crankshaft Support Groups Are Available To Measure Bent Crankshafts{0653,1202}

1977/11/07 Improved Crankshaft Main Bearings And Connecting Rod Bearings With Higher Strength Aluminum Alloy{1203,1219,1230}

1977/11/07 Precision Oil Pump Bearings Now Available{1304}

1977/11/14 New Electric Starting Motor Has Longer Brush Life{1453}

1977/11/14 Exhaust Valves With 30° Face Angle Now Used For Parts Service{1101,1103,1105}

1977/11/14 New Exhaust Manifolds Made Of Stronger Material{1059}

1977/11/21 New Elbow Between Turbocharger And Air Inlet Manifold Has Hole For Ether Starting Aid{1058,1456}