How do you replace the thermostat located on a 2000 Mazda Millenia?

Thermostat replacement

The thermostat is located in the thermostat housing at the engine side end of the upper radiator hose.

You have to drain the engine coolant from the radiator until it is below the level of where the thermostat is.

Make sure you don't spill any coolant, or you clean it up if you do. Antifreeze tastes sweet. Dogs, cats and other animals are very attracted to it. It is fatal when they drink it. For us, too.

2.3L engine: You should remove the charge air duct, air filter housing and resonator. Then take off the two thermostat housing bolts, open the housing and pull the thermostat.

2.5L engine: remove the hose mounting bolt and separate the pipe from the outlet housing. You'll find an O-ring between the hose and the housing. You need to replace that one with a new one. Remember to buy one before you start. The engine harness bracket bolt now has to be taken off, then put the wire harness out of the way. Take off the housing bolt, remove the housing cover, the thermostat as well as the gasket (remember to buy a new one before you start).

Before you put in the new thermostat, make sure the surfaces of both parts of the thermostat housing are very clean.

On putting in the new thermostat, the side where the spring is must point towards the engine; jiggle pin must face in the direction of the radiator. Some models have a tab on the thermostat that fits into a notch at the housing.

2.5L engine: Use a new gasket. Its projection should point in the flow direction of the radiator. Put the housing cover back. Apply the lower bolt first, but don't tighten it yet. Fix the engine harness bracket, but leave the bolt loose. Now tighten both bolts to 14-19 ft.lbs. Put the new O-ring between the pipe and the housing. To avoid damage to the 0-ring, make it wet with some coolant. Tighten the hose mounting bolt to 14-19 ft.lbs.

2.3L engine: Close the housing-thermostat assembly and tighten both bolts to 14-18 ft.lbs. Put back the resonator, air filter housing and charge air duct.

2.5L & 2.3L engine: Fill cooling system. Apply answer to "How do you bleed the coolant for a 1998 Mazda Millenia." This will prevent bad and costly surprises of an incompletely filled cooling system. Make sure there are no leaks.

First answer by ID1175786542. Last edit by ID1153989688. Question popularity: 65 [recommend question]