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Old 06-17-2012, 09:51 PM
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bluebee bluebee is offline
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Mein Auto: 02 BMW 525i M54 auto 130K
Originally Posted by rdl View Post
See this link
I was looking for that link! I knew you had answered it, but, I searched before posting that last re-request ... and I couldn't find it. I started to (erroneously) think it was never answered. Thanks for finding it for us!

Here's the answer you gave over there:

Originally Posted by rdl View Post
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 diaphragm 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 making it 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 valves open in overlap, and down the exhaust.

Can anyone report that they have succeeded in making bubbles with a properly functioning CCV?
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