As I'm getting ready for breaking the engine I just rebuilt (Skoda Estelle/120 '70s, RWD, rear mounted engine) I wanted to start checking things before firing it, even before cranking it. I made a rod that engages the oil pump shaft and with a drill I started pumping oil while, obviously, the engine is not running. I also attached an oil pressure gauge which comes with an idiot lamp. As the pump started to raise pressure, I got it blowing out through the oil filter gasket. Gauge shows good reading. Idiot lamp got turned off. So I tightened the filter further but still get pressure being blown.
Question, what could make this? The gasket is kinda old and I couldn't replace it since it has some special profile...and it was holding well before rebuild. Is oil pressure so violent at filter area to just escape if the gasket is not "new"?