Jeep Wrangler White Smoke on Startup

I often have people ask me if white smoke coming from their exhaust when they start their vehicle is normal or a sign of a problem.

Nine times out of ten, white smoke at startup is not a problem.

What Are The Causes of The White Smoke on Startup?

Vehicles should not just emit white smoke from the exhaust when you crank them. There are a few things that could contribute to this happening without being really bad but there are also some real problems that can be diagnosed because you saw white smoke at startup.

The Air Temperature and Condensation Burn Off

If it is really cold outside you may see white smoke when you crank the vehicle. If you can see white smoke when you breathe then you should not be worried if you see it coming out of your exhaust pipe on these mornings.

You will typically see a small amount of white smoke for up to one minute. If you see really thick white smoke, the smoke has an odor like burning oil, or your car is having other symptoms then it is not happening due to the temperature outside or condensation.

Leaking Intake Manifold Gasket

If your intake manifold gasket is worn or cracked there is a good chance that it will create white smoke that you can see coming from your exhaust when you crank the vehicle. 

To remedy this situation, you will need to change the manifold gasket. 

Oil Leaks

Leaking oil coming out of your piston rings will travel and mix with fuel and cause white/ bluish-white smoke to come out of the exhaust pipe. This smoke will often have an oily aroma that tells you it is produced by an oil leak.

This can be the start of some very serious problems. If you see white smoke coming out of the exhaust and the smoke is thick, or it comes out for longer than just a few seconds, then you need to investigate the cause.

Determining if you have an oil leak

One of the easiest ways to determine if oil is leaking from the vehicle is to check the oil level. If the level of oil drops suddenly or you often need to add a little oil then you have a leak. 

Look on the ground for signs of oil that have dripped from the vehicle.

Look under the hood for signs of oil on the hood or the other engine components.

Fuel Injector

Close up of old fuel injector

The fuel injectors in a vehicle inject the fuel into your engine’s internal combustion chamber. The fuel injectors do this at the precise right time. When your fuel injector sends the fuel into the chamber at the wrong time then you can get thick white smoke from the exhaust of the vehicle.

If the fuel injectors are the cause of the smoke there should also be other signs and symptoms to alert you to the problem. The white smoke should just be one piece of the warning puzzle.

  • If your fuel economy has gotten worse or you possibly have fuel leaks
  • Your engine may have been misfiring or backfiring lately
  • When your vehicle is idling it may sound like it is going to die
  • Your check engine light may be showing signs of a problem by flashing or being illuminated all of the time
  • Your vehicle may be slower to accelerate than normal

If you suspect the fuel injectors are the reason why you are seeing white smoke you need to get the vehicle into a shop. The mechanics at the shop can put the vehicle on a diagnostic machine to determine if the injectors are indeed the problem.

If the injectors are going bad you will need to replace them.

Cracks in the Engine Block

This is a pretty serious condition that no car owner wants to hear they have. If the engine block is cracked you have undoubtedly seen other warning signs besides just the white smoke.

Signs of a cracked engine block include [but are not limited to]:

  • Your engine may be overheating
  • You may have an obvious oil leak
  • You may have an obvious coolant leak
  • You may see smoke coming from the engine, not the exhaust
  • The engine may be running poorly due to the lack of compression

What causes an engine block to crack?

  • If the car gets overheated due to low coolant levels or inadequate coolant the block can crack from the heat stress this would cause
  • If the water pump on the vehicle fails the block can crack
  • Anything that causes severe overheating of the engine

What to do

If the engine block is cracked you need a mechanic to put a new block in. If you drive around with a cracked engine block for very long the engine will be placed under undue stress and will fail.

More Jeep Wrangler Related Articles You can Read
1. Jeep Wrangler Steering Wheel Jerks When Turning
2. Jeep Wrangler Knocking Noise When Accelerating
3. Why Is My Jeep Wrangler Jerking While Accelerating?


Should I Be Worried If I See White Smoke When I Start My Engine?

If you live in a colder climate this is very common. I would not worry unless I saw other symptoms of a problem.

How Much White Smoke from The Exhaust Is Considered a Problem?

When you first crank your automobile, especially if the outside temperature is pretty cool, then expect white smoke to be expelled for a period of thirty seconds or up to one minute.

Does White Smoke on Startup Indicate Low Engine Oil Levels?

White smoke on startup does not indicate low engine oil but it can be a symptom that you have an oil leak. If the smoke has a bluish tint you can be pretty sure that it has something to do with an oil leak.

Final Thoughts

White smoke coming from the exhaust is probably not a problem if it comes in tiny puffs for about 30 seconds after you crank the car. If the smoke is thick, or if it continues to come out after about one minute, then you need to find the problem.

About Brendan Burnett

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