Parts for your 2006 Nissan Navara-Radiator cap

2006 Nissan Navara radiator cap — what it does and when to replace it

Per Nissan’s technical literature, a 2006 Nissan Navara does use a pressure cap in its cooling system. Which type depends on the series. The D22 (still sold in 2006 in AU/NZ) has a traditional radiator cap on the radiator neck (Nissan Navara D22 Service Manual, CO – Cooling System, “Radiator Cap” test, relief pressure approx. 88–108 kPa). The D40 (launched 2005) places the pressure cap on the plastic reservoir/degassing tank, and the radiator itself has no cap (Nissan Navara D40 Service Manual, CO – Cooling System, “Reservoir Tank Cap” test, relief pressure approx. 78–98 kPa). So a “radiator cap” is relevant to 2006 Navara ownership, noting the D40’s cap lives on the expansion tank rather than the radiator.

On either setup, the cap is a small but critical part. It seals the cooling system and sets its operating pressure. By holding roughly 0.8–1.1 bar of pressure (check the stamping on the cap and the series spec above), the coolant’s boiling point is raised, helping the Navara keep its cool on long open-road drives, towing, or low-speed work under the bonnet. The cap’s valves let expanding coolant move to the reservoir when things heat up, then pull coolant back as the engine cools so hoses don’t collapse and air doesn’t sneak in.

For day-to-day care, it’s worth a look at every service. With the engine dead cold, inspect the cap’s rubber seals for cracks or flattening, make sure the spring-loaded centre valve moves freely, and check for crusty deposits around the neck or tank spout. If there’s dried coolant, a sweet smell, or the overflow bottle keeps filling and not returning, the cap may be the culprit.

A quick pressure-cap test is smart any time you’re chasing intermittent overheating or slow coolant loss. Most workshops use a cap tester to confirm it holds the specified relief pressure (D22 radiator cap typically 88–108 kPa, D40 reservoir cap typically 78–98 kPa). If it fails, replace it—caps are inexpensive insurance. As a rule of thumb, consider replacement every 3–5 years, or sooner if seals look tired, hoses collapse after cool-down, or temperatures creep up on climbs.

Always open the cap only when the engine is cold. If topping up, use the coolant type and mix recommended in the owner’s manual, and on D40 models fill via the reservoir/degassing tank rather than the radiator. A healthy cap helps prevent boil-over, air pockets, and premature water pump or heater core dramas—small part, big payoff for a 2006 Navara.

• Signs of a failing cap: random overheating, coolant stains or smell, collapsing upper hose after shut-down, reservoir that overflows or doesn’t draw back.
• Service tip: replace the cap any time you replace the radiator, reservoir tank, or after a major cooling system repair.

Popular questions about 2006 Nissan Navara radiator caps

Does a 2006 Navara have a radiator cap or a reservoir cap?
Both D22 and D40 use a pressure cap, but it’s fitted in different places. The 2006 D22 has a traditional cap on the radiator neck. The 2006 D40 uses a pressure cap on the plastic expansion/degassing tank, the radiator itself doesn’t have a cap. A quick look under the bonnet will show which layout the vehicle has.

What pressure cap does a 2006 Navara need?
Typical specs are around 0.8–1.1 bar, but it depends on the series. D22 radiator caps generally test at about 88–108 kPa. D40 reservoir caps are commonly 78–98 kPa. Check the cap’s stamping and the owner’s or service manual for the exact spec that matches the engine and market.

How often should the cap be replaced?
There’s no hard expiry, but every 3–5 years is a good preventive interval. Replace sooner if a pressure test fails, seals are perished, hoses collapse after cool-down, or there are signs of coolant escape around the neck or tank spout. It’s cheap, quick, and can save a lot of grief.