How do you change the thermostat in a 1985 Honda Accord?

Answer 1

You need a thermostat, a new gasket, a 10mm wrench, some anaerobic sealant, a tube of blue Loctite, a gasket scraper, some Honda antifreeze, a funnel, and a clean one-gallon pan. If you have a torque wrench, use it for this.Unhook the battery, stick the pan under the car, remove the radiator cap, turn the heater all the way on, and drain maybe half a gallon of coolant from your car. The official procedure is to drain it all, but as long as you drain enough to take the level below the thermostat you're fine.

Follow the upper radiator hose back to the engine and you'll see it connects to a big fitting with three 10mm bolts holding it on. The thermostat is in there. Remove the three bolts. Then remove the thermostat, remembering how it was positioned before you take it out. (Some people like to take a picture of it with their phone and you can certainly do that.) Scrape off the old gasket from both the block and the housing.

Set the new thermostat in place, oriented just like the old one was. Put a bead of sealant on both sides of the gasket, set it in place, and reinstall the housing. Put a little Loctite on the three bolts and thread them into the engine. If you have a torque wrench, the torque is 25 lb-ft; otherwise, snug plus half a turn is plenty.

Pour the coolant back into the radiator. Use the funnel to prevent spills. Put the cap back on.

Now for the important part: There is a nipple on the thermostat housing. It is for bleeding air from the cooling system. Open it (10mm wrench) and pour coolant into the overflow tank until a stream of bubble-free coolant comes out the nipple, then close it snug. Put the lid back on the overflow tank, clean up anything that had coolant on it, and you're done.