Parts for your 2017 Mitsubishi Asx-Thermostat

2017 Mitsubishi ASX Thermostat — what it does and when to replace it

Yes, the 2017 Mitsubishi ASX does use a thermostat in its engine cooling system. Technical sources confirm it’s a standard component: the Mitsubishi Motors service manual for ASX/Outlander Sport/RVR (GA-series, 2010–2017) lists a wax‑pellet thermostat in the water outlet housing (Group 14: Engine Cooling). The Mitsubishi ASA electronic parts catalogue likewise shows a thermostat assembly and seal for the 2.0L petrol (4B11) and diesel variants, and major aftermarket catalogues (e.g., Gates, Dayco) specify direct‑fit thermostats for this model.

On a 2017 ASX, the thermostat’s job is to get the engine up to operating temp quickly, then hold it steady. It sits in the housing where the upper radiator hose meets the engine, opening and closing with coolant temperature. Warm‑up is quicker (better fuel economy and cabin heat), and once hot, the thermostat meters flow to the radiator so the gauge doesn’t wander in stop‑start traffic or on long motorway runs.

They’re simple parts, but when a thermostat sticks, it can cause grief. Stuck closed can mean rapid overheating, stuck open can mean a cold engine that chews fuel and fogs the windscreen under the bonnet’s damp air.

• Common signs: slow warm‑up, fluctuating temp gauge, overheating, weak cabin heater, radiator fans running oddly, or coolant pushed into the overflow bottle.
• Good practice: replace the thermostat whenever the cooling system is overhauled (radiator, water pump) or if there’s any doubt about its operation.

There’s no fixed mileage for thermostats, but many workshops in AU/NZ treat them as preventative at around 8–10 years or 150,000 km, especially on vehicles doing lots of urban trips. Always use a quality thermostat and a new O‑ring/gasket. Refill with the specified Mitsubishi long‑life coolant (premixed to the correct ratio) and don’t mix coolant types.

DIYers should only tackle replacement on a fully cold engine. Drain enough coolant to drop the level below the housing, remove the intake ducting as needed, then unbolt the housing. Note the thermostat’s orientation (jiggle pin at the top on many units), clean the mating surfaces, install the new seal, torque the fasteners to the service‑manual spec, refill, and bleed the system. After a road test, check for leaks, stable temperature, proper fan cycling, and a firm upper hose. If in doubt, a trusted mechanic can sort it quickly and keep the ASX happy for the long haul.

Popular questions

Where is the thermostat on a 2017 Mitsubishi ASX?
It’s housed at the engine end of the upper radiator hose, in the water outlet on the cylinder head. On the 2.0L petrol, that’s towards the front of the engine bay. Access usually involves removing the intake snorkel and a couple of clamps and bolts.

When should the thermostat be replaced on a 2017 ASX?
Replace it if there are symptoms (overheating, slow warm‑up, wandering temp gauge), during major cooling system work, or preventatively around the 8–10 year/150,000 km mark. Always fit a new seal and fresh, correct‑spec coolant.

What coolant should be used after thermostat replacement?
Use the Mitsubishi‑specified long‑life coolant premix for the ASX and don’t mix brands or colours. A proper 50/50 premix protects against corrosion and ensures the thermostat and water pump live a long life.