Parts for your 2006 Toyota Caldina-Thermostat housing

2006 Toyota Caldina Thermostat Housing

Technical confirmation: Toyota’s own sources show the 2006 Caldina uses a thermostat housing. The Toyota Electronic Parts Catalog for the T240 series (ZZT241/245 1ZZ‑FE, AZT241/246 1AZ‑FSE, and ST246 3S‑GTE) lists a Water Inlet/Outlet (thermostat housing), and the Toyota Repair Manual cooling system sections illustrate the thermostat installed within that housing. That makes the thermostat-housing relevant and fitted on this model.

The thermostat housing on a 2006 Toyota Caldina is a cast aluminium unit that holds the engine’s thermostat and channels coolant between the block and the lower radiator hose. It positions the jiggle‑valve thermostat correctly, provides a bypass passage so the engine warms evenly, and often carries the coolant temperature sensor boss. Whether the car has the 1ZZ‑FE 1.8, 1AZ‑FSE 2.0 D‑4, or the ST246 3S‑GTE turbo, the housing does the same job—keeping coolant flow controlled until the engine reaches operating temp, then opening to prevent overheating. Because it seals against the block with an O‑ring or gasket, it’s also a common point to check for leaks, corrosion pitting around the flange, or hairline cracks at the hose neck after years of heat cycling.

As part of regular servicing, they’ll inspect the thermostat‑housing and the area under the bonnet for dried pink residue from Toyota Super Long Life Coolant, dampness around the lower radiator hose, and staining under the housing. Any of those signs, or symptoms such as slow warm‑up, fluctuating temperature, or an overheating episode, are a cue to test the thermostat and consider replacing the housing and seal together. On cars that have lived a hard life—like a GT‑Four driven spiritedly—the aluminium neck can wear where the hose clamps bite. Replacing the housing is straightforward: it’s a bolt‑on item and inexpensive compared with the cost of an overheated engine. When fitting a new thermostat, orient the jiggle valve to the 12 o’clock position as Toyota specifies, and use a new O‑ring or paper gasket with a light touch of coolant‑safe sealant only if the manual calls for it.

Best practice after refitting is to torque the bolts to spec from the workshop manual, reconnect the hose with a quality clamp, and refill with Toyota SLLC (pink) premix. Bleed the cooling system with the heater set to hot, then let the engine idle until the radiator fan cycles and air is purged, top up the reservoir to the mark. Under typical Kiwi and Aussie conditions, check the housing at each service and renew coolant at the recommended interval, the housing itself isn’t a routine replacement, but if there’s any leak, corrosion, or damage, swapping it together with the thermostat provides cheap insurance for many more kilometres.

Popular questions about a 2006 Toyota Caldina thermostat-housing

Where is the thermostat housing on a 2006 Caldina?
It sits where the lower radiator hose meets the engine. On all engines offered in 2006 (1ZZ‑FE, 1AZ‑FSE, 3S‑GTE), the housing bolts to the block and contains the thermostat. Look for the alloy outlet with two or three small bolts and the big hose clamped to its neck.

This spot is easy to find under the bonnet by tracing the lower hose from the radiator to the engine. Any signs of pink crust, coolant smell, or dampness around that junction suggest the housing or its seal needs attention.

Should the housing be replaced when changing the thermostat?
It isn’t mandatory, but it’s often smart. If the flange surface is pitted, the neck is grooved from clamps, or there’s any warping or hairline cracking, a fresh housing and new seal will help the new thermostat seal properly and avoid repeat leaks.

Many owners choose to replace the thermostat, O‑ring, and housing as a set, especially after any overheating, during a major coolant service, or when tidying up an older cooling system for long trips.

What coolant should be used and how should the system be bled?
Use Toyota Super Long Life Coolant (pink) premix and don’t mix it with green coolant. After refitting parts, fill slowly, set the heater to hot, and run the engine until the fan cycles to purge air. Top up the reservoir to the correct mark once cooled.

Proper bleeding prevents hot spots and erratic gauge behaviour. If the temperature climbs or the heater blows cold at idle, there may still be air in the system—revisit the bleed process.