I have a 1999 civic EX and today while going to work I was stuck in traffic for a long time due to a snowstorm. After a while my car started smoking crazy. The smoke was coming out from under the hood and from the vents. The interior looked like a hotbox and it was hard to see the road ahead. I quickly pulled into a parking and turned the engine off. WhenI opened the engine bay I could see that there was coolant on the head cover and on the radiator fan. I could hear the coolant boiling. Can someone please help out? Also, the heat gage was not showing a hot motor, it was at a normal height.

  • 1
    Maybe the radiator fans stopped working or were blocked by snow. The thermostat could have failed also. It needs to be professionally diagnosed.
    – Moab
    Feb 10, 2020 at 15:28
  • My guess is burst cooling hose.
    – zipzit
    Feb 10, 2020 at 15:39
  • 1
    ...failed cooling fan, already low coolant level, failed pressure cap etc.. Now your concern should probably be checking that the head gasket is OK, and tracing the cause of the overheat. If you're lucky the gasket will be fine, and the failure was a transient thing (eg as Moab suggests, airflow to the rad blocked by snow) - refill the coolant and off you go
    – Caius Jard
    Feb 10, 2020 at 16:16
  • 2
    Presumably the smoke was really steam, or was there smoke also?
    – HandyHowie
    Feb 10, 2020 at 16:59
  • 1
    The heater core may also have burst. That much steam on the inside of car and age of car would lead to this. But it probably burst due to overheating.
    – Jupiter
    Feb 10, 2020 at 17:20

1 Answer 1


Sounds like your radiator cap has gone bad and needs to be replaced. The cap has a rubber seal, which is prone to cracking in severe cold. Coolant will only boil and turn to steam if the pressurized system has been compromised, so you're losing pressure somewhere. And since you said Coolant was all over the fan and Valve covers my first guess would be the cap. Take it off and inspect it. If it's not the cap, then there may be a crack along the top of the radiator itself.

NOTE: Your car is 20 years old (high five) so it's earned the right to have a few part failures :)

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