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.