My turbo is smoking and it's brand new. The shaft has normal play in it so is one of my seals blown?
A. The term "blown seal" is widely used to describe a turbo that has oil coming out of it. In reality a turbocharger seal cannot become damaged until the freeplay of the shaft has increased to the point where the blades of the turbocharger have been rubbing against the housings. Blade contact usually requires more than .035" of side to side movement of the shaft. In some cases it is even possible to rub the blades and still not damage the seals.
If the turbo is new and the shaft isn't loose and bouncing off the housings, but oil is coming out of it chances are you can correct the problem without even taking the turbo back off the car.
The seals within the turbo are not meant to hold back a bearing housing that has become full of oil. They are designed to sling the oil mist and spray within the bearing housing away from the point where the shaft comes out each end. If the bearing housing becomes full of oil it will ooze out past even brand new seal rings.
The oil should freely drain out of the bearing housing as quickly as the engine supplies it. This is why the drain tube is so much larger than the supply tube. Gravity is the only force moving the oil out of the turbocharger. Any slight restriction in the oil drain tube, even a small silicone dingle berry, can slightly impede the draining of the oil and cause oil to back up into the bearing housing.
The crankcase vents are the second largest cause of oil loss from a good condition turbocharger. The seals in the turbocharger were designed with expectation that the pressure inside the compressor and turbine housing will always be greater than the pressure in the bearing housing. If this is ever not the case then oil will come out pass the seals. A restricted crankcase vent will cause this to happen. If the amount of ring blowby exceeds the ability of the crank vents to release the pressure positive pressure will build within the crankcase. This pressure within the crankcase can exceed the pressure inside the compressor and turbine housings under some operating conditions resulting in oil being driven pass the seals by the improperly biased pressure gradient across the seal rings. In severe cases it may be necessary to introduce vacuum pumps to deal with crankcase pressure, but these would be very severe high boost applications where even low percentages of blowby produce a high volume of crankcase vent flow.
Here you go nix this would be a good place to start. Pulled this FAQ right from forced performances website
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