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Blue and White Engine Smoke

In my neck of the woods whenever we see bluish-white smoke coming out of a vehicle’s tail pipe, we call it “shootin’ the blues.” This can happen on diesels, but it’s mostly predominant with older gasoline engines that have been sitting for awhile.

Ray Bohacz is Successful Farming’s Answer man. He says the most common cause for that is in the engine’s cylinder head. There is an intake port and an exhaust port, and the valves go through what is called a guide. A rubber seal fits over the guide and prevents oil from leaking into the intake port. When the seal deteriorates, oil gets through.

"Then what happens is that when the engine is started, the top of the piston has some oil in it. And when combustion happens, you have some bluish-white smoke," says Bohacz. "Some people call it blue, some people call it white. It’s depending upon the amount of oil."

A lot of people believe the engine is shot if they see the smoke. It might be something costly, but Bohacz says the culprit is usually the seal and something you can easily fix in the farm shop.

"You need to put compressed air in the cylinder either through the injector hole if it’s a diesel, or in a gas engine through the sparkplug hole and use a valve spring compressor," he says. "Remove the spring, the lock and retainer in the spring, and put a new seal on."

Bohacz says if you don’t take care of the problem, there will be a buildup of carbon on the back side of the valve. Once that happens, it will impede air flow into the engine, causing a lack of power and high fuel consumption. 

Watch Ray’s video discussing blue and white engine smoke. 

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