Parts for your 1999 Daihatsu Gran move-Thermostat

Thermostat for 1999 Daihatsu Gran Move

For the 1999 Daihatsu Gran Move (G300 series, commonly running the HC‑EJ 1.5 petrol), a conventional engine coolant thermostat is definitely fitted and relevant. This is confirmed by the Daihatsu G300/Pyzar–Gran Move workshop manual (cooling system section), plus Australian and New Zealand parts catalogues from Tridon and major belt/cooling catalogues that list a standard wax‑pellet thermostat for this model. Those sources note a normal opening temperature in the ballpark of 82–88°C.

The thermostat’s job is simple but critical: it holds coolant in the engine while it warms up, then meters flow to the radiator to keep temperature steady once you’re cruising. That means quicker warm‑ups, a toasty heater on cold mornings, better fuel economy and emissions, and far less risk of overcooling on the open road. When they fail, they usually stick open (slow warm‑up, weak heater, higher fuel use) or stick closed (rapid overheating).

On the Gran Move, the thermostat sits under the housing at the engine end of the upper radiator hose on the cylinder head. Access is straightforward with basic spanners. There’s no strict time‑based replacement interval in manufacturer literature, but on older cars it’s smart to replace the thermostat proactively during cooling system work (radiator, water pump, major hose service), or any time you see odd temperature swings, sluggish warm‑up, or overheating. Using the correct temperature rating matters—cheap low‑temp units can cause overcooling—so stick with reputable brands and match the OEM spec noted in the workshop manual or trusted AU/NZ catalogues.

• Always fit a new gasket or O‑ring, use a light smear of sealant only if the manual specifies.
• Orient the jiggle pin/bleed hole to the top so trapped air can escape.
• Refill with the right coolant mix, bleed air with the heater on hot, and check for leaks.
• Tighten housing bolts gently—it's an alloy housing and easy to strip. If they’re stubborn, give them a careful pre‑soak.
• After a short drive, recheck coolant level and hose clamps under the bonnet.

With the correct part and a careful bleed, the Gran Move’s cooling system will hold a rock‑steady temperature, look after the head gasket, and keep cabin heat and performance spot on.

Popular questions about 1999 Daihatsu Gran Move thermostats

What temperature thermostat should it run?
The Gran Move typically uses a thermostat that begins opening around the low‑80s Celsius and is fully open by the mid‑90s, as noted in the Daihatsu workshop manual and AU/NZ parts catalogues. If you’re in a warmer climate, stick with the standard spec rather than dropping to a cooler rating—overcooling can hurt fuel economy and driveability.

Where is the thermostat located?
It’s under the alloy housing at the engine end of the upper radiator hose on the cylinder head. Two or three fasteners hold the housing, once removed, the thermostat lifts out. Expect an O‑ring or paper gasket—replace it every time.

Should it be replaced on a schedule?
There’s no hard kilometre interval from the factory. Replace if there are symptoms (slow warm‑up, overheating, temperature hunting) or as preventative maintenance when doing coolant, radiator, or water pump work on an older Gran Move. Given the low cost, many owners treat it as cheap insurance every decade or so.