F200 gear box oil pressure

[Simon E]

I was filling up the gear box with new oil with the yamaha hand pump screwed into the four litre container I had the top screw just turned once so I could here the air coming out and when it reached level oil drained out I then went a little further and pushed oil out through the shaft seals .
I then removed the top screw and let the oil drain and level out .

My question is in regards to the shaft seals and weather this is a negative thing to do or a postive indicator of the condtion of the seals .?
The seals where replaced 100 hrs ago .

Thanks

[BaileysBoat]

Bad idea.

The seals are not designed to deal with hydralic pressure.

Fill with the vent plug removed.

[rodbolt17]

incredibly bad idea.
I have seen propshaft and shift shaft seals physically pushed out by doing that.
why not simply drain and fill it PER the service and OWNERS manual?