Parts for your 1998 Nissan Navara-Thermostat

1998 Nissan Navara Thermostat – What It Does and When to Replace It

Yes, a thermostat is absolutely fitted to the 1998 Nissan Navara. Technical sources including the Nissan D22 Factory Service Manual (Cooling System section), the Nissan FAST parts catalogue, and major aftermarket catalogues (Dayco, Gates) all list a thermostat located in the water inlet/thermostat housing on engines used in 1998 Navaras (such as TD27/QD32 diesels and KA24E petrol). It’s a standard part of the cooling system and essential for proper warm‑up and temperature control.

On this Navara, the thermostat’s job is to help the engine warm up quickly, then hold it steady at the designed operating temperature. It stays closed when cold so the engine reaches temp faster, then opens around the specified temperature to let coolant flow through the radiator. That keeps performance crisp, cabin heat reliable, and fuel use and emissions in check. A stuck‑open unit causes slow warm‑up and high fuel use, stuck‑closed risks overheating and engine damage.

While the thermostat isn’t usually a scheduled replacement item, it’s smart to check it any time cooling system work is done, or if there are temperature niggles. Many owners replace it preventatively every few years or after any overheating event.

• Common signs it’s due: takes ages to warm up, fluctuating temp gauge, weak heater output, or creeping temps under load.
• Fit a quality OEM‑spec thermostat and gasket/O‑ring. On these engines, the “jiggle”/bleed valve must sit at 12 o’clock to purge air.

Basic replacement tips for a 1998 Navara thermostat:

1. Start with a cool engine. Drain enough coolant to drop the level below the housing.
2. Remove the lower radiator hose from the housing, then the housing bolts. Note the old thermostat’s orientation.
3. Clean mating faces. Install the new thermostat and gasket/O‑ring, jiggle valve up.
4. Refit the housing and tighten to the factory spec (around 12–16 N·m on most D22 engines, check the workshop manual for your exact engine).
5. Refill with the correct Nissan‑approved ethylene glycol coolant mix. Bleed air with the heater on hot, use the bleed screw if fitted.
6. Check for leaks and confirm the gauge stabilises at normal with good cabin heat.

A fresh thermostat, healthy radiator cap, clean coolant, and good hoses keep a ’98 Nav humming along nicely under the bonnet—whether it’s towing, touring, or tackling a Kiwi backroad.

Popular questions about 1998 Nissan Navara thermostats

What temperature rating should the thermostat be?
Most 1998 Navara engines use a thermostat that opens around the low‑80s °C (commonly 82°C for diesels, petrol variants may list around 76.5–82°C). Always match what’s printed on the original part or follow the spec in the D22 service manual for your exact engine code.

Where is the thermostat located?
It sits in the thermostat housing at the front of the engine where the lower radiator hose connects. On TD/QD diesels it’s on the alternator side of the block, on the KA24E petrol it’s at the front near the timing cover. Access is straightforward with basic hand tools.

Should it be replaced as routine maintenance?
There’s no strict time/odometer interval in the factory schedule, but replacing it during major cooling system service, after an overheating event, or when symptoms show is good practice. Use a quality OEM‑spec unit and renew the gasket/O‑ring each time.