Why Does My Hyundai Blow White Smoke

Hyundai’s. If you’ve read title (and last weeks blog post), you might think that we’ve got a bone to pick with everyone’s favourite Korean manufacturer. However, as always, our Kashy mechanics actually have a deep love for this manufacturer and the cars they make.

So, with the apologies out of the way, why does your Hyundai blow white smoke out of the exhaust?

This nerve racking fault is a very common problem in both the i30 and Elantra from the early 2010’s and was only every prevalent on the 1.8L petrol engines. However, while only subject to a couple of models, having plumes of white smoke suddenly come out of the exhaust while driving is obviously cause for concern.

The problem really comes down to a part called a variable length intake manifold. This uses small flaps inside of the intake manifold to redirect the flow of air through either a long path (creating torque at lower speeds) or a shorter path (creating power at high RPM’s).

These variable length intake manifolds are actually an incredibly smart invention and means that engineers are able to make an engine for a car that feels a lot more rounded to drive than most. Because of this, they have actually found homes in a lot of modern engines from BMW to Ford.

Though the engine in the i30’s and Elantra’s were actually quite good motors for the time, this intake manifold was actually a rather simple short coming in the design.

Due to emissions laws, all modern engine essentially end up circulating some oil through the intake system when running. Because of this and in conjunction with the design of the intake manifold, it’s quite common for oil to build up in the manifold if the car is constantly driven gently.

While this is completely fine 99% of the time as grandma potters around to do the shopping, if there’s ever a situation where the car accelerates, the second half of the intake (where the oil sits) can open and engine oil is suddenly sucked into the combustion process.

As you may have caught on by now, this oil burns white and throws aforementioned plumes of smoke from the exhaust and can cause the car to run rough and even bring on an engine light.

So what is the solution to this problem?

Well first and foremost, if you’re reading this blog because it is happening to your car, talk to your mechanic. Even though this particular fault is rarely a problem, running engine oil through the engine has some serious risks from hydraulic locking to fowling spark plugs.

Otherwise, the solution is much more simple than you might think; At least once per week, accelerate to the speed-limit at full throttle. Prevention is often the best medicine and the best prevention for these Hyundai’s in particular is to drive them aggressively.

If you have any questions about this blog post, would like a second opinion from a mechanic or would like to find an honest mechanic in Brisbane, check out Kashy here.

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Lachlan @ Kashy

Lachlan @ Kashy

A blog from an avid auto enthusiast and our Kashy head mechanic. We try to answer your questions about cars and the automotive industry in Australia.