A needle that never climbs is a fault too
Most people only worry about the temperature gauge when it goes high. A needle that stays low, or takes far longer than it used to before it reaches the middle, is also telling you something, and it is easy to miss because nothing seems wrong.
The usual cause is a thermostat stuck open. The thermostat is a valve that keeps coolant away from the radiator until the engine is warm. When it sticks open, coolant flows through the radiator from the first minute, and the engine struggles to reach its working temperature, especially on a cool morning or at a steady road speed with plenty of air coming through the grille.
The signs are quiet:
- The gauge sits low or creeps up slowly, and drops again on a long downhill or a cold run.
- The heater is lukewarm for longer than it should be, or never gets properly hot.
- Fuel use creeps up. An engine that runs cool is often given extra fuel by its computer, which assumes it is still warming up.
- A check engine light may come on for engine temperature, though not every vehicle reports it.
Why it is worth fixing
An engine is built to run at its working temperature. Run cool for months, it wears faster, burns more fuel, and leaves moisture in the oil that a properly warm engine would drive off. On a farm pickup that spends its day in short hops between the field, the bins and town, it may barely be warm at all.
A stuck thermostat is also a part that is often replaced alongside a coolant service, which makes it a sensible job to combine.
What to say when you book
How long the gauge takes to reach the middle now, compared with how it used to behave, and whether the heater is weak. The national cooling system page covers the opposite problem, a gauge that climbs. A weak heater with a normal gauge may point elsewhere, and A/C service and engine repair are both here.
About this store
The Henderson store runs sixteen services and is managed by Derrick Madewell.
See the national cooling system page for all 33 locations.