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Does E85 Cause White Smoke On Startup?

Does E85 Cause White Smoke On Startup?

Does E85 Cause White Smoke On Startup?

Some car owners who use E85 have reported seeing white smoke come out of their exhaust pipe on start up. White smoke is usually bad news, so it's no surprise that some people are concerned about this. If your car's running on E85 and you see white smoke coming out of your exhaust pipe on start up, you have nothing to worry about.

It's Not White Smoke. It's Steam.

The good news is E85 doesn't cause white smoke. It can cause steam to come out of the tailpipe. Steam isn't a bad thing. It's an indicator of extra water in the exhaust system. It's easy to confuse steam with white smoke. Steam happens for two reasons:

  1. Ethanol's burning reaction produces significantly more water than gasoline.
  2. Ethanol is not as energy dense as gasoline.

When ethanol is burned, it turns into water and carbon dioxide, just like gasoline, but the difference is that water content is significantly higher with ethanol and the carbon dioxide content is lower. Because ethanol has lower energy content compared to gasoline, your engine burns up more ethanol than gasoline. When you start up your car, this introduces even more water to your exhaust system. That steam will leave the tailpipe, and some of the moisture will stay in the exhaust pipe. Water is a byproduct of all combustion, including E85 and gasoline.  Although it's common to see water dripping out of the tailpipe, regardless of whether your vehicle runs on gasoline or E85, there is slightly more dripping when running on E85.

It Could Still Be White Smoke

It's possible that what you're seeing is in fact white smoke. If you're dealing with white smoke, E85 is not the cause. The most common cause of white smoke is a coolant leak in your engine. It can't hurt to check your vehicle for a coolant leak to rule it out. Other causes of white smoke worth checking out include:

  • Cracked or warped cylinder head (this may cause a coolant leak)
  • Cracked engine block
  • Head gasket failure

The good news is that E85 helps to prevent these types of engine problems. The problems listed above are often caused by excess heat over time. E85 burns cooler than gasoline, so there is less heat stress on the engine.

August 30, 2021

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