2.3 LITER. Adapter bolt. A threaded rod with a drive head (such as hex, 12 point, torx, etc) on one end used to secure The Engine Coolant Outlet Housing or related components. A threaded rod with a drive head (such as hex, 12 point, torx, etc.) on one end used to secure The Engine Coolant Thermostat to it's mounting point. All Required. Bolt for The brackets that hold The Radiator Hose. Bolt used to fasten The Engine Intake Manifold. Cooling System Bypass Line Adapter Bolt. Engine Control Module Bolt. Engine Coolant Reservoir Bolt. Engine Coolant Thermostat Housing Bolt. Engine Water Pump Bolt.