Quote:
Originally Posted by Smallblock454
Hi jamesp,
If there is a way in, in general there also has to be a way out. The only way i could imagine is that materials expand when they get hot and so there is no way out, while materials shrink when they get cold and than there is a leak so that the oil can get in over a long time.
Markus
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Markus, the way in and way out is at the IMS bearing seal to inner race interface. That area is sealed with a thin rubber lip much like the edge of a windshield wiper, but much smaller. When the air in the IMS tube heats up and pressurizes, that seal is no match for the delta pressure so gas escapes through it. The same thing happens in reverse when the tube cools down, only now there's a tiny bit of oil available to accompany the air through the bearing and back into the tube. That is why very nasty overcooked oil is found in the IMS when the bearing is removed. This process happens slowly over time every time the engine is heated then cooled, in other words every time the car us used.
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