vinkodex.Thermostat housing: the plastic goes brittle and the coolant leaks
Typically between 100,000 and 150,000 km. It does not show up on every car.
expensive
severity
between 100,000 and 150,000 km
mileage
2
sources
2 sources next to the write-up.
The fault
How you spot it
The thermostat housing is made of plastic, and the hose connector is moulded as part of it. Under thermal cycling the material goes brittle and then cracks. The fault appears between 100 000 and 150 000 kilometres.
The leak appears under the intake manifold and runs down from there. What the owner notices is that the coolant level keeps falling, and a smell of coolant is noticeable in the cabin. If the crack opens further, the engine overheats, and from then on the cylinder head and the gasket are at risk as well.
Replacing the housing is not expensive, and it is worth replacing it with an aluminium part instead of the factory plastic: the metal version does not go brittle.
Which model
Who it affects
The card opens the generation, the engine or the transmission.
Engines and transmissions
Engine
IQDA
Engine
IQDB
Engine
IQDC
Engine
IQJA
Engine
IQJC
Engine
PNBA
Engine
PNDA
Engine
PNDD
Engine
XTDA
Engine
XTDB
vinkodex.Checklist
Thermostat housing: the plastic goes brittle and the coolant leaks
What you would check for this fault. Take it to the car.
Before you buy
Checklist
What you tick stays on this device only.
Sources
How we know
Information, not an expert opinion
We write the descriptions, and we put the source next to them. A person reviews them before they go out. They are still information, not a technical expert opinion.
- A fault on the list does not mean the car you are looking at has it.
- A fault missing from the list does not mean the model is fault-free. Write-ups are made model by model. Not all of them are done.
- You decide whether to buy. This is no substitute for an inspection. That needs a workshop and a history check.