1981/03/30 Caterpillar

Low Engine Temperatures: Install Check Valve{1353,1355,1370,1380}

Usage:

3406, 3408 Truck Engines

Operation of 3406 and 3408 Truck Engines at below normal engine temperatures can cause increased fuel consumption and increased engine component wear.

Engine operation at temperatures below 71°C (160°F) is usually found when heater performance is not correct and/or the temperature gauge indication is low.

Check the engine operation temperatures with a gauge of known accuracy. This will give a check of the truck's engine temperature gauge.

The main cause of low engine temperatures is the flow of coolant past the temperature regulators at a temperature below 71°C (160°F). Identification of the leakage circuit is necessary to correct the problem. To do this, check:

1. Operation of the water temperature regulator.

2. Make sure the correct regulator cover assembly is used. Use of the wrong cover assembly can cause low engine temperatures. See the March 24, 1980 SERVICE MAGAZINE article, "Inspect Regulator Cover Assembly When Overcooling Is A Problem."

If the water temperature regulator works correctly and the correct regulator cover assembly is used, an 8N9071 Valve Assembly can be installed in the air vent line. The air vent line, which goes from the cylinder head to the radiator, is used to remove air from the engine cooling system. Without the check valve, it is possible for coolant to flow through the air vent line when the water temperature regulator is closed. The check valve prevents this coolant flow.

Caterpillar Information System:

1981/03/30 Check All Settings When Fuel Injection Pump Group Is Installed{1286,1264,1251,1253}

1981/03/23 New Tool Makes Glow Plug Wire Removal Easier {0622,0621,1403}

1981/03/23 Correction To Torque Specification For Locknuts On Valve Clearance Adjustment Screws Of Engines Equipped With Jacobs Engine Brakes {1119,1102}

1981/03/23 Longer Cable Assembly Now Used In The 9S2000 Flowmeter {0651}

1981/03/23 Fuel Pressure Relief Valve Is Shown Inverted (Wrong End Up) In Parts Book Illustrations {1253,1286}

1981/03/23 6V4009 Dowel Driver Available {0622,1101}

1981/03/23 6V2029 Fixture Group Available For Adjustment Of Air/Fuel Ratio Control {0626,1278,0652}

1981/03/16 New Shield Assemblies Used In Water Shielded Manifold Group{1067}

1981/03/16 New Inlet And Exhaust Valves And Valve Guides Have Tighter Fit To Prevent Corrosion And Guide Wear{1104,1105,1101,1103,1108,1109}

1981/03/16 5P1075 And 5P1076 Washers Have A Different Design{7553,0680}

1981/03/16 Approximate Liquid (Refill) Capacities Added To Specifications Page In Parts Book{0374}

1981/03/09 Clean Electrical Contacts In Exhaust Gas Recirculation (E.G.R.) Switch Group And Cover Assembly Before Installation{1080}

1981/03/30 6V3197 Spacer, 6V3041 Tool Group Available For Use During Removal and Installation Of Piston Pin Bearings{0622,1219,1218,1214}

1981/03/30 6V3150 Engine Pressure Group Gives Direct Indication Of Manifold Pressure{0651,1058}

1981/03/30 Electrical Information For EGR (Exhaust Gas Recirculation) Systems On 3208 Truck Engines So Equipped{1080}

1981/03/30 Brass Plug Now Used Instead Of Steel Plug In Sea Water Aftercooler{1063}

1981/04/06 Woodward Governor Available For Parallel Generator Applications{1289,1264}

1981/04/06 New Spacer And Plate Used In Transmission Lower Shaft Groups{3307}

1981/04/06 New Temperature Range Recommendation For Multi-Viscosity Oil In Power Shift Transmissions{3179,3155,3159}

1981/04/06 Use Heat-Indication Products To Measure Parts Temperatures{0651}

1981/04/06 Cooling System Cleaner Removes Rust And Corrosion{1350,1353,1354}

1981/04/06 Correct Refill Capacity For Engine Oil{1318}

1981/04/06 New Piston Ring Assemblies Give Improved Ring And Cylinder Liner Life{1215,1213}

1981/04/06 Improve Use Of Engine Service Manual Microfiche{0374}