1991/05/20 Caterpillar

Two Scavenge Screens Now Used In Scavenge Oil Pumps{1312}

Usage:

3500 Family Of Vehicular Engines;
D11N, 776B Tractors;
777B, 785, 789 Trucks

SUPPLEMENT: 06/17/91

Service Magazine; May 20, 1991; Page 19; "Two Scavenge Screens Now Used In Scavenge Oil Pumps" on 3500 Family of Engines. In Chart A, part number 1N3326 should be 1N3226.

--------------- END SUPPLEMENT ---------------

Description of Change: A stronger steel wire screen replaces the former brass wire screen in the scavenge oil pumps of 3500 Vehicular Engines. Also, a perforated steel plate has been added ahead of the screen to catch any large debris. Formerly, the brass screen could wear and let debris enter the scavenge pump.

Adaptable To: Chart A shows the part changes in the scavenge pump groups. Chart B shows the effective serial numbers of this change. The new screens are replacements for the former screens.

Caterpillar Information System:

1991/05/20 Replace Camshaft And Install New Lifters If Pitting, Spalling, Or Wear Occurs On Lobes Of 4N0599 And 4N0602 Camshafts In Fuel Injection Pump Groups{1251,1253}

1991/05/20 Procedure To Retain Oil Pump When Pump Mounting Pad On Cylinder Block Is Broken{1201,1304}

1991/05/20 Cylinder Kits Not Recommended For Use In 3400 Family of Marine Engines And D8N Tractors{1214}

1991/05/20 Do Not Weld Repair Worn Wheel Spindles For Off-Highway Trucks Or Wheel Tractor-Scrapers{4002,4205,4234}

1991/05/13 Unwanted Engine Shutdown Caused By "01" And/Or "04" Diagnostic; New "09" Diagnostic Available With 8T9881-8 Electronic Control Module (ECM){4490}

1991/05/13 Engine Updates Help Prevent Piston Seizures{1214,1252,1265,1274,1355,1383,1393,1456}

1991/05/13 Rear Gear (Cam Drive) Groups Improved{1206,1201,1212,7551,7552,7553}

1991/05/13 New Specification For Exhaust Valve Clearance{1123,1121,1105}

1991/05/13 Replacing A 3176...(2YG) Truck Engine With A 1991 3176...(7LG) Truck Engine{1000,1119,1408,1901}

1991/05/13 Component Changes For 1991 Model 3176 (7LGH, 43Z) Engines{1052,1087,1119,1215,1290,1292,1304,1361,1362,1378,1408,1901,1902,1912}

1991/05/13 Larger O-ring Seal Available For Oil Supply Port In Governor Housing{1264}

1991/05/06 New Altronics Interface Boxes{1552,1566}

1991/05/20 New Speed Setting Clutch Group For 3161 Woodward Governors{1265}

1991/05/20 Correct Testing of Sensing Switches{7400,7402,7422}

1991/05/27 Expected Future Air Conditioning Service Requirements{7320,1802}

1991/05/27 Technical Marketing Information (TMI) System for Commercial Engine Products{0337,0334,0336}

1991/05/27 Smaller Connecting Rod Bolt Used In 4W6425 Air Compressor; Use Correct Torque{1803}

1991/05/27 New Fuel Manifolds And Clamps Reduce Vibration Of Fuel Lines{1252,1702}

1991/06/03 New Deutsch HD-10® Electrical Connectors Used{1400,1408}

1991/06/03 Reference Emissions Graph Helps Determine Oxides Of Nitrogen{1050}

1991/06/03 New Oil Drain Assembly Used; Be Sure To Correctly Tighten Drain Plugs, Port Plugs, And Pipe Plugs In Oil Pans{1302}

1991/06/10 New Timing Specifications For 3500 Spark-Ignited Engines{1552}

1991/06/10 1,1,1-Trichloroethane May Damage Deutsch C-E Electrical Connectors{1400,0645,0785,1450,1550,1900,3168,3225,3418,4294,4323,4450,5485,5700,7400,7450}

1991/06/17 New Three-Ring Pistons And New Rings Used In New Piston And Rod Groups To Provide Improved Oil Control{1214,1215}