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The fourth generation Volkswagen Jetta, also called the MK4 or the Bora, is Volkswagen's family sedan.

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Smoking problem with 1.8t mk4 Jetta

At start up it puts out a cloud of bluish white smoke but then disappears. It doesn’t smoke anymore unless revved at a higher rpms. Head was just rebuilt due to a bent valve problem. New turbo installed as well as a new PCV valve. No coolant loss.it Seemed to have some oil consumption but after replacing the PCV valve about 100 miles ago the oil consumption has been greatly reduced but still smoking out of the exhaust. Car has roughly 152k miles on it. I Also did a compression test. Everything seemed normal. Was wondering if anyone had any ideas as to what might be causing the smoke. Thanks!

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When you had the heads rebuilt did they replace the valve guides? If the guides are worn then when the car sits with oil in the cylinder heads, the oil seeps past the seals on the valve guide and puts oil into the cylinder if the valve is open or into the manifold if its closed but either way that oil ends up being burned on startup giving you your blue cloud of smoke on startup . Replacing the guide seals or the guides themselves will fix the problem . Hope this helps

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Ok thanks!! I believe they were replaced but I’m not for sure I will definitely find out. Would be able to tell if the valve guide seals are leaking with a compression test?

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@josbo not with a compression test but you should with a leakdown test

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Johnathan O will be eternally grateful.
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