1990/02/26 Caterpillar

New Water Temperature Regulator Used {1355,1353}

Usage:

3406, 3406B Truck Engines

Reference: Service Magazine; November 16, 1987; Page 7; "New Water Temperature Regulator Helps Prevent Overcooling," on 3406, 3406B Truck Engines.

Effective with 3406B (4MG26525, 8TC4481) Truck Engines, the "no-leak" 7C3095 Water Temperature Regulator [88°C (190°F) opening] is being used. Illustration 1 shows the two configurations of the new regulator. They both have the nonmetallic seats to insure good seals. The new 7C3095 Water Temperature Regulator is a direct replacement for the former 4W4842 Water Temperature Regulator. The 3S9643 Seal in the thermostat housing should also be replaced to prevent leakage around the housing.

Illustration 1. 7C3095 Water Temperature Regulator.

NOTE: To minimize corrosion and/or carbon build-up on internal engine components, the jacket water temperature MUST be kept above 79°C (175°F). If overcooling continues after the regulator is replaced, install a 4.8 mm (.19") orifice or 8N9071 Check Valve in the engine vent line between the cylinder head and radiator. See Illustration 2 for engine vent line location.

Illustration 2. Location of components.

The former 4W4842 Regulator Temperature Regulator is still available for use in some applications.

NOTE: Please make parts personnel aware of the need to order the correct thermostat.

Caterpillar Information System:

1990/02/26 Improved 1W2076 Cover Used In Fuel Ratio Control Group {1278}

1990/02/26 Resealing Engine Plugs And Fittings; New 5P3413 Pipe Sealant (with Teflon) Available {0649,1100,1200}

1990/02/26 Cat Natural Gas Engine Oil (NGEO) Available For NACD Only {1318}

1990/02/26 Caterpillar Parts And Service Information Available On Dealer Computer Terminals (NACD Dealers Only) {0331,0336,0374,0375}

1990/02/19 Special Instruction Available With Replacement Information For 7C2662, 7C2664 Or 7C3507 VR3 Voltage Regulators{4467}

1990/02/19 Improvements Made To Water Pumps; New Groups/Parts Available For Certain Applications{1364,1361}

1990/02/12 Identification Of Turbocharger And Fuel System Components{1250,1700,1052}

1990/02/12 New Exhaust Manifold Stud Available{1059}

1990/02/12 New Oil Cooler Gasket Has Bead On Only One Side{1378}

1990/02/05 New Oil Filler Group, Oil Level Guide Group And Contactor Group Used {1316,1326}

1990/01/29 Correct Throttle Linkage Adjustment{1265}

1990/01/29 New Seal Used In Governor Fastener Group{1264}

1990/02/26 Improved Head Gasket Used; Service Tips {1124,1216,1221,7568}

1990/02/26 Welded Crankshafts {1202}

1990/02/26 New Inlet/Exhaust Valve With Improved Valve Seat Angle, New Valve Guide, New Cylinder Head Assemblies With New Inlet Valve Seats {1100,1103,1104,1105}

1990/03/05 4C5623 Smoke Candles Can Help Locate Air Leaks in Cab{7301,7325}

1990/03/05 Do Not Use Lubricant On Sticking Start (Ignition) Switches{1416}

1990/03/05 Changing Mounting Position Of 9F3099 And 302266 Magnetic Switches (Relays) May Extend Service Life{1426}

1990/03/05 New Fuel Inlet Fitting Eliminates Breakage; New Screen Used In Inlet Fitting{1250,1252,1261}

1990/03/05 Preventive Maintenance (PM) Kits Available For 3116 Truck Engines{7258,0645,1261,1318,1352,7542}

1990/03/05 2N4620 Rubber Drive Block Reinstated For Parts Service{3305}

1990/03/05 New Plug Used In Front Housing For Fuel Injection Control Group{1151,1298}

1990/03/05 New Basic Turbocharger Groups And Cartridge Groups With Improved Compressor Seals, Thrust Bearings, And Hollow Shaft For Reduced Heat Soak{1053,1077}

1990/03/05 New Piston Pin Retainer Used In 3600 Family Of Engines{1214}