How to Replace a Thermostat in a 2000 Toyota Sienna

The thermostat in a 2000 Toyota Sienna helps control the flow of coolant between the radiator and the engine. When the thermostat fails, coolant will either be stuck in the engine, causing an overheating condition, or circulating constantly, causing the same problem. If your Sienna overheats, it can cause serious harm to the engine and could be expensive to repair. To fix the problem, you have to remove the thermostat and replace it with a new one, which should take about an hour to do.

Instructions

1

Place the drain pan underneath the middle of the radiator, just below the petcock. Open the petcock by hand and drain the coolant into the drain pan. Pop the hood and remove the air cleaner cap and hose using the pliers and a 3/8-inch ratchet and socket.

2

Unbolt the engine coolant temperature sensor connections at the thermostat on the front of the engine using your hands. Unbolt the water inlet pipe from the engine block, then pull it off using your hands. Note the orientation of the thermostat and remove it and the stock O-ring from the engine.

3

Set the replacement thermostat in the same orientation as the original and install the replacement O-ring in the original location. Bolt the housing to the engine using the 3/8-inch ratchet and socket. Reinstall the air cleaner cap and hose using the pliers and ratchet.

4

Open the radiator cap. Fill the radiator with the 50-50 pre-diluted coolant. Start the Sienna and let it run for 15 minutes with the heater set on the high position. Turn off the van and allow the engine to cool for an hour. Then open the radiator cap and fill up the radiator with additional coolant until it reaches the top.