Q: Overheating to 3/4

asked by on

My car overheats to 3/4 of the way, stays for about 3-5 seconds then drops back to normal. There are days that it does this and other days it does not. What could it be? Would there be air in the system? I looked this up online and some say it could be the head gasket but my oil is not Milky, exhaust does not blow out white. I checked under the hood and the coolant reservoir seems like it overfillls and spills out if the cap. When I remove the radiator cap it seems like there is no pressure, it doesn't make any sound when I open it (I check it when the engine is cold).

My car has 238401 miles.
My car has a manual transmission.

Overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, a clogged radiator or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. You may also have a water pump that is beginning to fail. Water pumps often times will begin to produce a bit of a whining sound when they are starting to fail. A common problem also associated with this is the water pump may begin to leak around the water pump shaft due to the seal being damaged. In addition to leaking around the pump, you may have a leak elsewhere in the cooling system coming from one of the hoses going to or from the radiator. Lastly, you may have a failing cylinder head gasket allowing coolant to leak from the water passages into the cylinders resulting in the coolant being burnt in the combustion chamber with the fuel. If this is the case, you may also notice a bit of white smoke coming from your exhaust which is a product of the coolant being turned into a steam like vapor. I would suggest having an expert from Your Mechanic come to your home to diagnose your cooling system.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Overheating to 3/4

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: The exhaust system is loud when started, sound is more concentrated towards front of car. What could be the problem?

Loud exhaust noise could be due to deterioration or breakage of the internal baffles in components such as the resonator and muffler as well as leaks at pipe joints or even at the manifold on the engine. To determine the...

Q: The engine light is on and the code is P0420 - Catalyst System Efficiency Below Threshold Bank . What part do I need to fix it?

While a number of things like a faulty oxygen sensor or exhaust leak can cause fault code P0420 to be set, the most common fault is the catalytic converter itself. However, as a replacement can be very expensive, your best...

Q: What does it mean if the Brake System indicator comes on in the dash?

The Brake light on the dash of your car is designed to come on as a warning and as a reminder in different situations. Here’s what you need to know: The light will turn on if the parking brake...

Related articles

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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.