Skip the auto shop - Our mechanics make house calls

Q: Intermittent overheating

asked by on

Car overheats after driving on the highway. Fans come on but very briefly. Maybe 5 or 10 seconds. No leaks. Had thermostat replaced and radiator cap.

My car has 158000 miles.
My car has a manual transmission.

Hey there. This may suggest that the coolant fan relay switch may not be working properly. When you car is moving down the freeway at higher speeds, the engine gets a lot of cooling assistance just simply from the air passing through the radiator and into the engine bay which can cause an otherwise overheating situation to not be as noticeable until the car slows down or comes to a stop. When the coolant temperature reaches a certain point, there is a relay that triggers the coolant fans to come and then tells them when to turn off once the coolant has cooled down sufficiently. When this is not working properly you may notice the temperature moving up and down erratically like this. If you need further help having this resolved, a certified technician from YourMechanic can come to your car’s location to diagnose the overheating issue and guide you through any needed repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Brake pedal touches floorboard

You are going to have to have the brakes completely inspected for leaks. You most likely have a leak from somewhere if the fluid was low. Once leak is located then check all pads and rotors for need to replace...

Q: cooled is full in my car but radiator not take cooled for cold..as a result tempreature is so high after 15 km..run

If I understand you correctly, your radiator stays cool and the engine overheats. If the engine thermostat is stuck closed, it will restrict coolant flow to the radiator and the engine will overheat. Have a mechanic inspect the overheating...

Q: clutch pedal droppedto floor

There are a limited number of issues that can cause the clutch pedal to drop to the floor, and stay there. A failed clutch pressure plate, failed clutch master/slave cylinder, malfunctioning clutch pedal assembly, or having air in the clutch...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...