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Vehicle vibrates a little when at a stop and starts to overheat , once I get going the temperature starts dropping back to middle. What do you think the problem is?

  • Have you had the raditor checked? Is it blocked with leaves? The forced air cooling, called ram effect, is making a difference when the car is moving. – Solar Mike Aug 12 at 15:59
  • As SolarMike mentioned in his comment the additional airflow over the radiator when you're moving is why it's not overheating when you are moving. Unfortunately that doesn't hugely narrow down the root cause of the overheating - it could be various things (low coolant, radiator fans not operating, partially blocked radiator etc). Can you tell us what the make/model/year of the car is and what (if any) other symptoms you have? – motosubatsu Aug 12 at 16:46
  • I vote the radiator fans are not coming on. – Moab Aug 13 at 20:42
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Does it actually overheat, or does it just go very near the red portion of the meter, with a sound of the radiator fan running?

If the latter, it's perfectly normal. I have had every single car with no start/stop that I owned do the same.

As there's no airflow at standstill, the radiator fan is needed. Its starting point is purposefully larger than the point where the thermostat kicks in.

So, if you normally see your temperature at 90 degrees, and at standstill they climb to 100 degrees and then the radiator fan kicks in, but the red portion starts only from 110 degrees, don't worry. Your car is working just as designed.

Edit: in a perfectly functional system, the fan kick-in temperature is what determines the max temperature the car should encounter. So, if the temperatures climb significantly even AFTER the fan has kicked in, you might want to get your cooling system checked. In a fully working system, the temperature might rise very slightly after the fan kicks in, but then the temperature will soon become lower, perhaps even so low that the fan stops spinning, until the temperatures rise and the fan kicks in again.

And oh, if you don't know whether the fan is on, it is off. The fan is loud! Trust me, you will hear it.

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    Agree if the needle never gets to the red there should be no issue, however, every vehicle I've ever owned has never climbed as you described unless there's an issue with the cooling system ... and that goes back to my first car which was a 72 Chevelle :o) There has been many cars since then! – Pᴀᴜʟsᴛᴇʀ2 Aug 12 at 17:24
  • Ok, perhaps the 105 degrees is a bit excessive. It was last 2011 when I had a non start/stop car so I don't remember the exact fan kick-on temperature... I'll edit to 100 degrees. :) – juhist Aug 12 at 17:28
  • Every car I've ever owned has had zero issues maintaining mid-range temps when stopped for short or extended periods of time. Often times I will get home and the kids are peacefully sleeping so I let that sucker run for over 30 minutes sometimes. – MonkeyZeus Aug 12 at 18:35
  • @MonkeyZeus It probably depends on the ambient temperature. During a hot summer day, the fan kick-in temperature is what should determine the maximum temperature the car ever encounters. During a cold or mild day, it's the thermostat that determines the temperature. – juhist Aug 12 at 18:41

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