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Q: Blue smoke oil leak

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Blue smoke comes out of 1 of my tail pipes in my car, and it’s not heavy. Oil is leaking upward under pressure on 1 of my vertical cylinder shaped motors or pumps on top of the valve cover. I’m not sure which. I’m also getting codes on my dashboard. Do you know what’s going on?

Hello. The valve cover and the spark plug tube seals may be leaking oil causing the blue smoke you see coming from the tail pipe of your 2004 BMW 745Li. The valve cover gasket and spark plug tube seals are designed to keep oil in the cylinder head for lubrication. When the spark plug tube seals fail, it causes oil to get down into the spark plug tube and oil burns during the combustion process. When this happens, it is possible for blue smoke to come out from the tail pipe.

Additionally, it would be a good idea to have your Check Engine Light inspected by a certified technician, who will be able to determine what the codes on your dashboard are indicating. The mechanic should also assist you with inspecting the valve cover gasket, repairing the valve cover gasket, and inspecting the spark plug well in order to determine the exact cause of the oil leak.

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