I have a 2002 VW Jetta (so an MK4) and it's a GLS.

I've been having problems with my battery dying. I checked the alternator and battery, both passed.

Anyways, I decided to let it idle for a long time to let the battery fully charge. I left my car running. I came back out about 2 hours later, and saw some thin smoke (so thin it almost looked like vapor, but it was dark out) come from the engine and I immediately turned it off.

The thing is, I have no idea how long it was overheating. And what's weird was, the temp gage was all the way down as if the car had been running cold. I know the car was running hot because I smelled burning, ,as well as if it's running for that long, a car should AT LEAST be at operating temperature.

Did my engine blow up? Could I have melted internal parts?

  • You first need to check the type of smoke, check if it is coolant or oil. The temp gauge reading low may signify a failing water temp sensor which made the car overheat.
    – method
    Feb 8, 2017 at 7:54
  • 1
    Consider this an important lesson: don't let the car idle so that battery will be fully charged. You may be breaking the law (many places limit idling to few minutes) and the insurance company doesn't like what you did if somebody steals the car. Instead, take a leisurely long drive so that airflow cools the radiator or purchase a battery charger. But anyway, I think @method has found the cause for the overheating.
    – juhist
    Feb 8, 2017 at 11:35
  • OP it's been a month, how's that car doing?
    – elrobis
    Mar 10, 2017 at 19:11
  • Car is doing fine. It was th waterpump. So due to that, I had to get the timing belt, crankshaft seals, etc etc replaced. Hadn't had the money or time. Getting it fixed now. Headgasket hasn't blown.
    – Josh Holly
    Jun 4, 2017 at 5:54

1 Answer 1


Sounds to me like there is no coolant in it. The temp sensor is reading low because it's not immersed in coolant. If it was still running OK when you turned it off you might get away with topping the coolant up. But it's possible it did some damage, cracked head or blown headgasket is a possibilty

  • prey for the latter cracked had is a pain you have to find one then get it skimmed and then still replace head gasket and i prey for you that in cooling one of the pistons did not seize up or your block is basically totaled
    – Barkermn01
    Feb 8, 2017 at 23:36

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