White smoke coming out of exhaust

2003 NISSAN ALTIMA
350,000 MILES • 2.4L • 4 CYL • 2WD • AUTOMATIC
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MIKE HALL2
  • MEMBER
  • 1 POST
I changed my valve cover and spark plugs when I realized two of my spark plug wells were filled with oil and misfiring. Now when I rev the car white smoke that smells like gas comes out and I'm wondering if that's just the excess oil that was left after draining the spark plug wells burning off?
Nov 7, 2019 at 9:27 PM
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SCGRANTURISMO
  • ASE Certified Mechanic
  • 4,897 POSTS
  • ASE Certified Mechanic
Hello,

White smoke coming from your vehicle's exhaust system that has a sweet smell to it is usually a sign that coolant is being burnt in your engine's combustion chambers. This usually indicates a blown head gasket, but other causes are a cracked cylinder head, cracked engine block, or on some vehicles the intake manifold has water ports that can leak into the intake manifold and enter the combustion chambers that way.Here are a few links below explaining what's going on and a couple of possible culprits:

https://www.2carpros.com/articles/white-smoke-or-steam-coming-from-the-exhaust-pipe
https://www.2carpros.com/articles/head-gasket-blown-test
https://www.2carpros.com/articles/how-to-test-engine-compression

Having said that, a little bit of steam coming out of your exhaust pipe is a normal function of a catalytic converter, as water is a byproduct of the catalytic conversion of the vehicle's exhaust. This water can easily turn to steam as the hot exhaust evaporates it. A good way to tell if you have a coolant leak problem into the engine's combustion chambers is to watch the coolant level. If it doesn't go down, then it's not being lost and is probably just steam from the catalytic process.

Thanks,
Alex
2CarPros
Nov 8, 2019 at 5:12 AM
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