Parts for your 2009 Suzuki Splash-Thermostat

2009 Suzuki Splash Thermostat: purpose, servicing and replacement

Based on Suzuki’s workshop literature for the Splash (covering the K10B/K12B petrol and D13A DDiS diesel engines) and the Suzuki Electronic Parts Catalogue, the 2009 Suzuki Splash is fitted with a conventional wax‑pellet thermostat housed in the engine’s coolant outlet. So yes, a thermostat is absolutely relevant and used on this model.

The thermostat’s job is to help the Splash warm up quickly and then hold a steady operating temperature, typically in the mid‑80s to low‑90s °C range. By staying shut when the engine’s cold, it speeds up warm‑up for better fuel economy, lower emissions and a decent heater under the dash. Once it reaches its set point, it opens and meters coolant flow through the radiator to keep temps stable, even on a hot Aussie or Kiwi summer arvo or slogging up a long hill.

As these cars age, the thermostat and its plastic housing seal can harden or stick. If it’s stuck open, the Splash may take ages to reach temperature, run rich, and the heater will feel weak. Stuck closed, and it’ll overheat quickly. Either way, it’s worth sorting early to protect the head gasket and keep the little Suzuki happy.

Thermostats aren’t a strict “replace by kilometres” item, but they’re cheap insurance when there are cooling issues, during a coolant change, or any time the housing is disturbed. Many techs will recommend replacement around the 10‑year mark or when chasing vague overheating/cold‑running faults. On the Splash, the thermostat assembly sits where the upper radiator hose meets the engine, access is straightforward on the petrol engines and a touch tighter on the DDiS.

• Use an OEM or quality aftermarket thermostat with the correct opening temperature.
• Always fit a new O‑ring/gasket and clean the mating surfaces.
• Refill with the correct spec coolant mixed with demineralised water (commonly 50/50), set the heater to hot, bleed air thoroughly, and recheck levels after a drive.
• Torque fasteners to workshop spec and inspect the plastic housing for hairline cracks or leaks.
• Dispose of old coolant responsibly – it’s toxic and attractive to pets.

Signs it’s time to act include the temp gauge wandering, slow warm‑up, the radiator fan running oddly, poor cabin heat, or any coolant stains around the thermostat housing. A quick pressure test and an OBD scan of coolant temperature will usually confirm what’s going on.

Popular questions

Where is the thermostat on a 2009 Suzuki Splash?
On the petrol K10B/K12B engines, it’s integrated into the plastic outlet housing at the engine end of the upper radiator hose, near the front of the engine. On the DDiS diesel, it’s in a similar outlet housing but packaging is tighter around the EGR and intake gear, so removing the airbox or ducting can help visibility and access.

What symptoms point to a bad thermostat on a Splash?
Typical signs are slow warm‑up and a heater that never gets properly hot (stuck open), or overheating and a hard upper hose (stuck closed). You might also see the temperature gauge hunting, poor fuel economy, or a check engine light with coolant temp readings that don’t make sense when viewed on a scan tool.

Do I need to bleed the cooling system after changing the thermostat?
Yes. Refill with the correct coolant mix, set the heater to full hot, and bleed any air via the bleed point or by gently massaging the hoses while idling with the cap off until bubbles stop. Top up the radiator and overflow, then recheck the level after the first proper drive once it’s cooled down.