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Old 06-11-2012, 06:43 PM
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Originally Posted by bluebee View Post
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Note: I will run the test again, taking more care to keep the water-filled parallel lines vertical.

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I felt absolutely NO RESISTANCE to blowing into the CCV upper vent tube whether the
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There is no need to keep the lines vertical, parallel, any particular shape or anything else. The only thing that matters is the vertical distance between the two water levels. Keeping the two legs of the "U" vertical & together does make it easier to measure though.
I'm afraid that the reading of 8" you got indicates that the CCV is suspect, assuming they were vertical inches.

I appreciate that the "blow for bubbles test" has been recommended for some time. It has never made sense to me. (Doesn't work for me either) Making bubbles would require pressurizing the CCV chambers in order to force air down to the dipstick guidetube and bubble through the oil in the sump.
But, while the engine is operating the CCV is keeping the port to the inlet manifold open "just the right amount" so that the hose (which the CCV thinks should be connected to the crankcase) has 4 - 6" w.c. vacuum. Any pressure rise generated by blowing into the pipe would cause the CCV diaphram to open the port wider to overcome the effect and maintain vacuum.
When the engine is stopped, the CCV default position is for the port to inlet manifold to be fully open; again impossible to generate pressure to bubble through the oil. Any pressure would go to the inlet manifold, past the throttle toward the engine air filter, or though a cylinder that has both valve open in overlap and down the exhaust.

Can anyone report that they have succeeded in making bubbles with a properly functioning CCV?
If so, please disregard my theory above.
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