Toyota 90916-03093 Thermostat

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Before proceeding with any thermostat replacement, it is important to perform a few checks. First, check the coolant level and the tension of the drive belt. Additionally, check the operation of the temperature gauge to ensure it is functioning properly. If the engine takes a long time to warm up, it is likely that the thermostat is stuck open, and it should be replaced with a new one. On the other hand, if the engine runs hot and the lower radiator hose isn't hot but the engine is, it indicates that the thermostat is stuck in the closed position, requiring replacement. However, if the lower radiator hose is hot, it indicates that the coolant is circulating and the thermostat is open. In case the engine has overheated, it could be due to leaking cylinder head gaskets, scuffed pistons, or warped/cracked cylinder heads. For the replacement process, start by disconnecting the cable from the negative terminal of the battery and draining the cooling system. If you're working on a V6 engine, remove the engine cover. Proceed to detach the thermostat housing from the engine, being prepared for some coolant spillage as the gasket seal is broken. The radiator hose can be left attached to the housing unless the housing itself needs replacement. Remove the thermostat, taking note of its installation direction in the housing, and ensure to thoroughly clean the sealing surfaces. To install the new thermostat, attach a new gasket to it if you're working on a four-cylinder engine, ensuring it fits evenly all the way around. On V6 models, install a new O-ring in the housing groove. Place the thermostat in position, making sure the jiggle pin, if present, is at the highest point for four-cylinder models. Proceed to install the thermostat housing, using a new gasket for four-cylinder models. Tighten the housing fasteners to the specified torque and reassemble the remaining components in reverse order. Finally, refill the cooling system, start the engine, and check for any leaks or abnormalities in its operation.

As the thermostat ages, it may become slower to react to changes in water temperature and can eventually stick in the open or closed position. This can lead to problems such as slow warm-up or rapid overheating. Before assuming the thermostat is to blame for a cooling system problem, it is important to check the coolant level and ensure there is no airlock in the system. If the engine takes a long time to warm up or the temperature gauge reading seems inaccurate, the thermostat could be stuck open or missing altogether. If the engine runs hot and the radiator top hose is not hot, the thermostat is likely stuck closed and needs to be replaced. On the other hand, if the radiator top hose is hot, it indicates that the coolant is flowing and the thermostat is open. To roughly test the thermostat's operation, start the engine and monitor the temperature of the radiator top hose. If it remains cold for a while and then quickly warms up, the thermostat is functioning properly. If not, the thermostat should be removed and tested. The removal process involves draining the coolant and disconnecting the thermostat housing. The thermostat can then be tested by heating it in water and checking for proper opening and closing. If it fails the test or sticks in either position, it should be replaced. When refitting the thermostat, a new O-ring should be used and the cover nut/bolt should be tightened to the specified torque. Finally, the cooling system should be refilled.

Before assuming the thermostat is the cause of a cooling system problem, it is important to perform a thorough check. Verify the coolant level, drive belt tension, and the operation of the temperature gauge or light. If the engine takes a long time to warm up, indicating a stuck-open thermostat, it should be replaced with a new one. In case the engine runs hot and the right (passenger's side) radiator hose is not hot while the engine is, it suggests a closed thermostat preventing coolant flow to the radiator. In this situation, replacing the thermostat is necessary. Conversely, if the hose is hot, it signifies that the coolant is flowing and the thermostat is open. For the thermostat replacement, start by removing the radiator cover and plastic lower engine covers for 2004 through 2009 models. Drain the coolant from the radiator. On 2010 and later models, disconnect the coolant hose from the inlet air filter, detach the wiring harness clamp, and remove the inlet air filter assembly by removing three bolts and the dipstick tube for clearance. Detach the thermostat housing from the engine, being prepared for some coolant spillage as the gasket seal is broken. The radiator hose can remain attached unless the housing itself needs replacement. Remove the thermostat, noting its installation direction, and thoroughly clean the sealing surfaces. During installation, fit a new gasket evenly onto the thermostat, ensuring proper alignment. Install the thermostat and housing, positioning the jiggle pin at the highest point. Tighten the housing fasteners to the specified torque, and then reinstall the remaining components in the reverse order of removal. Refill the cooling system, start the engine, and check for any leaks or issues with the system's operation.

No you will also need to purchase 1 of the gasket # 16325-62010