Blue smoke from the exhaust: What problem does it indicate?

Blue smoke from the exhaust
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Blue smoke from the exhaust means only one thing: engine oil enters the cylinder space. The more engine oil penetrates into the cylinders, the more the car smokes.

In addition to the blue smoke from the exhaust, an accompanying phenomenon of oil penetration into the cylinders is also excessiveengine oil consumption.


Engine oil can get into the cylinder space in several ways, for example, through damaged cylinder head gasket, worn piston rings, cylinder liners, or worn pistons or the cylinders themselves. In the case of supercharged engines, however, blue smoke from the exhaust can also point to the turbocharger itself.

Like other engine components, the turbocharger is lubricated and cooled with engine oil as well. If the turbocharger has worn bearings or a damaged seal, it injects compressed air and engine oil into the cylinders.

All these problems, except for a worn turbocharger, are manifested similarly, namely loss of compression. It should be added that not all of the mentioned problems occur on all cylinders simultaneously, so it is very easy to determine a faulty cylinder by inspecting and comparing the spark plugs or by measuring the compression in one cylinder and comparing it with other cylinders.

A worn turbocharger can be detected by inspecting the air filter. If there are black oil stains on the air filter, it is almost certain that the turbocharger is leaking engine oil into the cylinder compartment.

Even though identifying the problem with engine oil penetrating into the cylinder space is relatively easy, solving it is not so easy. Any of these problems, except those related to the turbocharger, require an engine overhaul and, therefore, a repair for which you will spend a lot of money.

If it is an old car with little value, you can top up the engine oil regularly and continue driving until you can. The reason is simple: engine overhaul could exceed the price of the entire car. In the case of a worn turbocharger, the situation is somewhat better.

In such a case, however, the turbocharger needs to be overhauled or replaced with a new one, which is also not the cheapest repair.


In any case, it does not matter whether it is a worn turbocharger or wear in the cylinder area. Blue smoke from the exhaust signals a serious problem that can trouble you and your wallet, and it is necessary to solve it as soon as possible.