Hi. Thanks for using JA! I will try and help you out.
The C15 engine does not have an OCV filter. Sorry. It only has a baffle under the valve cover that the blowby tube connects to.
If your engine has enough blowby to push out the dipstick, that is way to much. I have seen this before. There are 3 things that can cause this to happen.
First is a worn engine air compressor.
Second is the High pressure turbo. It's the one that connects directly to the exhaust manifold. Basically, it is pushing exhaust gas down the oil drain tube and elevating the crankcase pressure.
And lastly is worn cylinders.
Please let me know if you need more help or have more questions.