Cooling & Overheating
Temperature gauge running hot, steam, coolant leaks and when to stop driving.
6 answers
- Get it checked soon
Why does my temperature gauge stay low? Is my thermostat stuck open?
If the temperature gauge stays near C, or drops on the highway, after you've driven long enough to warm up, the most common cause is a thermostat stuck open: coolant flows through the radiator all the time, so the engine never reaches its normal temperature. The other usual causes are a faulty coolant temperature sensor or gauge, low coolant, or a cooling fan that won't shut off; it isn't an emergency like overheating, but get it fixed soon, because a cold-running engine burns more fuel, heats the cabin poorly and wears faster.
- Not urgent
Why does my windshield keep fogging up, and how do I clear it fast?
Fog on the inside of the windshield is moisture from warm, humid cabin air condensing on cold glass; clear it fastest by pressing the defrost button, keeping the A/C on (it dries the air, even in winter) and switching from recirculate to fresh outside air. If the glass fogs again and again, look for extra moisture or a problem: wet carpets, a leaking door or window seal, a clogged cabin air filter, or a greasy film with a sweet smell, which points to a leaking heater core.
- Get it checked soon
Why is my car heater blowing cold air?
The most common cause is low engine coolant, so check the reservoir first with the engine cold; after that, the usual suspects are a thermostat stuck open (the temperature gauge never reaches its normal spot), air trapped in the cooling system, a clogged heater core, or a faulty blend door or climate control. If the heater goes cold while the temperature gauge climbs, pull over: that points to a coolant, belt or water pump problem that can overheat the engine.
- Get it checked soon
Why does my car smell sweet? Is coolant leaking?
A sweet, maple-syrup smell is almost always engine coolant (antifreeze) leaking and burning off on hot engine parts; if the smell is strongest inside the car with foggy windows or a damp passenger-side carpet, the heater core is the likely source. Check the coolant reservoir with the engine cold, watch your temperature gauge, and get the leak found soon, because a car that keeps losing coolant will eventually overheat.
How often should you change engine coolant?
Follow the interval in your owner's manual, which on most modern cars is long: Toyota's pink Super Long Life Coolant goes 100,000 miles first, then every 50,000; GM's DEX-COOL lasts up to 5 years or 150,000 miles; Ford's current Motorcraft Yellow goes 10 years or 200,000 miles first, then every 5 years or 100,000. Older-style green silicate coolant is the exception and needs changing about every 2 years or 30,000 miles.
- Act now
My car is overheating. What should I do?
Pull over as soon as it's safe, turn off the air conditioning, and if you see steam or leaking coolant or the gauge is in the red, shut the engine off and let it cool for at least 30 minutes before touching anything. Never open the radiator or coolant cap while the engine is hot, and don't keep driving an overheating engine; the usual causes are low coolant from a leak, a stuck thermostat, a cooling fan that isn't running, a bad belt or water pump, or a clogged radiator.