1981/04/09 Caterpillar


Low Engine Temperatures: Install Check Valve

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 water temperature regulators at a temperature below 71 °C (160°F). Identification of the leakage circuit is necessary to corect 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 12, 1980 ENGINE NEWS 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:

1981/03/06 New Governor Spring Available For Specific Engine Applications
1981/03/06 New O-ring Seal Used In Egr (exhaust Gas Recirculation) Control Has Better Resistance To Heat Damage
1981/03/06 Check Oil Level Carefully To Prevent Operation With Too Much Oil In Engine Crankcase
1981/03/06 Two New Exhaust Manifolds Available For Replacement Of Single Rear Manifold To Prevent Broken Studs
1981/03/06 Do Not Adjust The Fuel Setting Or High Idle Higher Than Necessary
1981/03/06 Modification Of Flywheel Prevents Loose Clutch Pilot Bearing
1981/03/06 Later Pistons Have A Smaller Number Of Drain Holes In Oil Ring Groove
1981/03/06 New Turbocharger, Turbocharger Oil Lines Group And Aftercooler Air Lines Group Used
1981/03/06 High Concentration Of Aluminum In Oil Analysis Can Be The Result Of Rocker Arm Support Wear
1981/03/06 List Of Service Publications
1981/03/06 Changes Have Been Made To Caterpillar Service Literature
1981/02/04 New, One-piece Valve Lifter Used
1981/04/09 6V4163 Bit And 6V4164 Driver Now Available For Removal Of Bolts For Flyweight Carrier
1981/04/09 Correction To Torque Specification For Locknuts On Valve Clearance Adjustment Screws Of Engines Equipped With Jacobs Engine Brakes
1981/04/09 Special Studs And Nuts Available For Exhaust Manifolds On Engines Used In Heavy Load Conditions
1981/04/09 Two New Oil Filter Assemblies Available; Always Use Correct Oil Filter And Follow Caterpillar Change Intervals
1981/04/09 Cooling System Cleaner Removes Rust And Corrosion
1981/04/09 Correct Refill Capacity For Engine Oil
1981/04/09 6V3197 Spacer, 6V3041 Tool Group Available For Use During Removal And Installation Of Piston Pin Bearings
1981/04/09 Clean Electrical Contacts In Exhaust Gas Recirculation (e.g.r.) Switch Group And Cover Assembly Before Installation
1981/04/09 Electrical Information For Egr (exhaust Gas Recirculation) Systems On 3208 Truck Engines So Equipped
1981/04/09 Improve Use Of Engine Service Manual Microfiche
1981/04/09 List Of Service Publications
1981/04/09 Check All Settings When Fuel Injection Pump Group Is Installed
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