M-B 300D W123 Blow-By Tests

Blowby test on my 1984 & 1985 M-B 300D w/ OM917.952 engines. Mileage is unknown on both engines. The original 1985 engine seized at 330K miles with cracked rings and failed pistons. The replacement engine is 1982 (? block stamps) and appeared recently rebuilt since ~405 psig compression in all cylinders. Shows no particles in the backlit vent flow and runs 18 sec when blocked (ignore my verbal count).
The 1984 also has unknown mileage. It measured 320-350 psig compression ~15K miles ago. It shows particles in the vent flow and can feel more flow, plus dances the oil cap in that poor-man's test. Blocking the vent kills the engine in 6 sec hot and 5 sec cold, which suggest that thicker oil doesn't seal the rings appreciably better. This result suggests similar ring-cylinder wear as the compression test. This engine still starts in 2 sec on 30 F mornings (no block heater), after running the glow plugs per dash lamp.
The reason the engine dies when the vent is blocked is that crankcase pressure builds and it is connected to the Injection Pump (IP). That gas pressure acts on the vacuum shutdown valve at the rear of the IP to pull the stop lever, starving the IP of fuel. Comparable results depends on the IP body being sealed (esp. top gasket) and that all IP's require the same force on the stop lever. Shutdown valves are likely comparable since the same diaphragm area.
I'm keeping the 1985, but plan to sell the 1984 since no longer need two 300D. The 1984 served a son thru medical school and residency. See Sacramento cl in future. Sharp eyes will notice I installed a 1985 CA frame-mounted air cleaner and vacuum amplifier (blue saucer) in the 1984. Also, a vacuum-switched coolant valve in place of the quirky mono-valve for the heater core.