Parts for your 2018 Mitsubishi Eclipse cross-Thermostat housing

2018 Mitsubishi Eclipse Cross Thermostat Housing

Technical sources confirm the 2018 Mitsubishi Eclipse Cross is fitted with a thermostat housing. The Mitsubishi Electronic Parts Catalogue (ASA) for GK/GU-series Eclipse Cross lists a water outlet/thermostat housing assembly for the 1.5‑litre turbo petrol (4B40) and applicable diesel variants, and the Mitsubishi Workshop Manual cooling-system section details removal/installation of the thermostat and housing. Aftermarket catalogues from well-known brands also list a direct-fit thermostat housing for this model, backing up its use on the vehicle.

On this Eclipse Cross, the thermostat housing does more than just hold the thermostat. It routes coolant from the engine to the radiator, seals the system with an O‑ring or gasket, provides mounting for temperature sensors, and often includes a bleed point. Its job is to help the engine warm up quickly, then keep it in that sweet operating temp zone for performance and longevity.

As part of routine servicing, it’s smart to keep an eye on the housing and nearby hoses. Plastic/composite housings can warp or crack with age and heat cycles, and alloy ones can corrode around hose necks. Tell‑tales include pink/white dried coolant crust, a sweet coolant whiff after a drive, drops under the front of the car, or an engine that runs too cold or too hot. A check-engine light with a P0128 code (coolant temp below regulating threshold) can also point to thermostat trouble.

• Inspect for seepage around the housing, hose clamps and sensor bosses every 10,000–15,000 km service.
• Replace the thermostat O‑ring whenever the housing is removed.
• Refresh coolant to the correct spec and mix, use Mitsubishi‑approved long‑life coolant and demineralised water if mixing.

When replacement’s due, wait for a stone‑cold engine. Drain enough coolant to drop the level below the housing, remove intake ducting for access, unplug any sensors, then loosen the clamps and the housing bolts. Clean the mating surface carefully, fit a new thermostat and seal, and torque the bolts to workshop‑manual spec. Refill slowly, open the bleed (if fitted), set the heater to HOT, idle until the fans cycle, squeeze the upper hose to purge air, then top up the radiator and overflow. After a day’s driving, recheck levels and for any weeping.

There’s no fixed replacement interval, but many techs in Australia and New Zealand will recommend inspecting from about 100,000–150,000 km or 7–10 years, and replacing if there’s any doubt. Using quality coolant and fresh clamps helps the new housing live a long, leak‑free life under the bonnet.

Popular questions

Where is the thermostat housing on a 2018 Mitsubishi Eclipse Cross?

It’s mounted on the cylinder head at the front of the engine, forming the outlet where the upper radiator hose attaches. On the 1.5T petrol, look low to mid height under the bonnet, slightly to the passenger side, tucked near the turbo plumbing and intake ducting. Removing the engine cover and shifting the intake pipe usually gives a clear view.

What are common signs the thermostat housing needs attention?

Common signs include coolant smell, dried pink/white residue around the housing, damp hose connections, a slowly dropping coolant level, or temperature gauge oddities. A P0128 code or sluggish cabin heat can suggest a stuck‑open thermostat, while overheating and hard upper hose pressure can point to a stuck‑closed thermostat or a sealing issue.

Can the thermostat be replaced without changing the housing?

Yes, if the housing is in good nick. The thermostat and O‑ring are service items and can be swapped on their own. If the housing is cracked, warped, corroded, or the sensor boss is leaking, replace the complete housing assembly to avoid repeat visits. New clamps and a fresh gasket/O‑ring are cheap insurance.