Thermostat Housing
| ITEM | DESCRIPTION |
|---|---|
| 1 | Screw (3 Off) |
| 2 | Upper Body |
| 3 | Lower Body |
| 4 | Thermostat |
| 5 | Seal |
The thermostat is a multi-stage device located in the coolant pump inlet to provide fast response and control of the engine outlet temperature.
The thermostat housing has 4 connections. The lower connection receives a quick fit connector which receives coolant from the radiator lower hose and the automatic transmission fluid cooler. The larger upper connection is connected through a hose, water supply tube and water outlet to the cylinder block. The flow from this connection is governed by the thermostat. A connection at the side provides flow to the coolant pump and a smaller connection from this receives coolant return from the heater core and the coolant expansion tank.
The thermostat allows rapid engine warm-up by preventing coolant flow through the radiator and by limiting coolant flow through the cylinder block when the engine is cold. During warm-up and at engines speeds above approximately 3, 500 Revolutions Per Minute (RPM), a by-pass valve opens to control the coolant flow and pressure, to protect the engine components. When the thermostat opening reaches 6 mm (0.24 in.), the by-pass flow is shut-off. When the thermostat opening exceeds 6 mm (0.24 in.), the radiator coolant flow is further controlled up to the point where the thermostat is fully open. At this point maximum radiator coolant flow is achieved to provide maximum cooling.
The thermostat begins to open at 88 - 90°C (190 - 194°F) and is fully open at 102°C (216°F).