How to Replace Thermostat and Water Passage Housings 03-07 Honda Accord
Difficulty: Advanced · About 180 min · Honda Accord
Replace the thermostat and water passage housings on a 2003–07 Honda Accord, supporting the engine before bracket removal and bleeding coolant afterward.
Tools you will need
- Drain pan
- 10 mm socket
- 12 mm socket
- 14 mm socket
- 17 mm socket
- Needle-nose pliers
- Sandpaper
- Torque wrench
Parts and supplies
- Thermostat and housing
- Water passage housing
- Coolant
Steps
Drain coolant and disconnect the lower hose
Let the engine cool fully, drain the radiator into a pan, and close the drain. Release the lower radiator hose clamp and disconnect the hose at the engine side.
Remove the fans and reservoir
Unbolt and move the coolant reservoir aside. Disconnect the fan wiring and upper radiator hose, then remove the fan shroud fasteners and lift the fans clear.
Remove the thermostat housing
Remove the housing bolts and release any wiring clips attached to it. Lift out the thermostat housing and keep coolant from spilling onto electrical components.
Support the engine and move the mount bracket
Support the engine with a properly rated support before loosening its mount bracket. Remove the bracket and passage-block fasteners, then move the block aside carefully.
Remove and clean the water passage housing
Disconnect the passage hose and remove the housing. Clean corrosion from the mating surface without scratching it, then inspect the hose and seals for damage.
Install the passage housing and bracket
Position the replacement housing with its seal and reconnect the hose. Reinstall the aluminum passage block and engine mount bracket, tightening fasteners to the vehicle's specification.
Install the thermostat and cooling hardware
Fit the thermostat in its correct orientation and reinstall the housing. Reinstall the fan shroud, reservoir, and radiator hoses, reconnecting all wiring and clamps.
Refill and bleed the cooling system
Fill with the specified coolant and bleed air using the vehicle procedure. Run the heater as directed, watch for leaks and stable temperature, then recheck coolant after the engine cools.
Check your vehicle’s repair manual for exact specifications and fit.