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After my car has been running for a while and I park I can see steam coming from the hood. It doesn’t stop until the car cools off. I check the radiator it’s full of water/ coolant, overflow is it in between minimum and max.. I checked it oil while it was cooled off and it’s also in between minimum and Max. I just bought the car so I don’t know exactly when the last oil change was. The check engine light comes on but goes off and was off the last time I noticed the steamenter image description here

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Have the codes read. (If you're in the US, many auto parts stores like AutoZone will do this for free. Do not pay a dealer diagnostic fee.) Even if the light is off, the ECU will store the codes from the last time the light came on. Alternatively, you can get a cheap bluetooth or wifi OBD-2 module for about $20 and scan it yourself with your smartphone. Check Amazon.)

I'd recommend drawing a line on the side of the overflow tank where the coolant level is - use a sharpy and/or some masking tape - and keep an eye on it to see if you're losing any coolant. A little bit of lost coolant can make a lot of steam.

Assuming the car is running fine, you may have a cracked or loose radiator hose, or a break in the radiator, or a failing radiator cap which is the cheapest option. You can pressure test the coolant system (or, if you are so inclined, have a repair shop do it for you) which will reveal any leaks.

(See also this thread about a bad radiator cap.)

Whatever you do, don't let the car run out of coolant and keep an eye on the temperature gauge. Overheating will destroy your engine.

Also, obviously, keep an eye on your oil level. If the steam smells like steam, and not gag-me-with-a-shovel oil smoke, it's likely just a leaking hose somewhere.

  • OK I’ll definitely have AutoZone check the check engine light. It looks like steam but it could be smoke.. I really don’t know.. I do have a small oil leak. I was told bc it’s an older car it probably needs the gaskets changed.. ty for your help – Kd Maulden Feb 21 at 19:35
  • Also, could it be oil leaking on something to make it smoke, it might not be steam... the thermostat shows it going from cold in the morning to heating up to the halfway point on gauge so I think that’s working fine and hasn’t overheated yet. I’ve only had this car for 2 months now..... help... I’ll take any suggestions – Kd Maulden Feb 21 at 20:39
  • @KdMaulden It it was oil smoke, it will smell terrible. Also, steam dissipates pretty quickly, while oil smoke does not. But, if you had an oil leak that was dripping onto the exhaust manifold or catalytic converter, it would definitely burn (and potentially catch fire if the leak is severe). – 3Dave Feb 21 at 22:07
  • @KdMaulden Really, don't discount the possibility of a bad radiator cap or overflow tank cap. They have to hold ~15PSI when the car is warm. If they're not up to the task, you'll get steam escaping. – 3Dave Feb 21 at 22:20

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