Sounds like nothing to worry about because it might not be blow-by, just crankcase harmonics. Those 4 cyl engines have a long stroke and short rods, so there is always a rather large air displacement below the 2 opposing piston pairs every 180 degrees of crank rotation. Big excitement at the fill hole is just something that goes along with long-stroke 4's.
Why the short rods (and long stroke) are worth mentioning is because lower rod-to-stroke length ratios impart a less-linear rate of piston acceleration/deceleration as it travels the bore. That just means that while the piston accelerates with an increasing rate from TDC, the
rate of acceleration slows down mid-bore and then speeds up again around BDC and repeats. So compared to crankshaft degrees, the piston is getting more ahead of- and then falling behind the crankshaft at every stroke vs a longer rod. That means that the piston is not only accelerating and decelerating, but it's
rate of acceleration in a single stroke speeds up and slows down again. So in addition to there being 1.2L of displacement whacking back and forth under the piston pairs, there also becomes a secondary pressure harmonic in the crankcase centered around the irregular rate of piston acceleration.
Contrarily, a longer rod and/or shorter stroke exhibits a more sinusoidal rate of accel/decel, without the brief inversion of piston acceleration rate exhibited by the K24, and all other short rod 4 cyl engines.
Basically it's normal for the engine design to have such excitement at the fill hole. If you really investigated, you might discover that it's just a low frequency harmonic, rather than a significant exodus of crankcase gasses.
You can see how Rod to stroke length ratio affects piston acceleration, the K24 in question would be very close to the blue line.