Well as the title states I need some help with some brake issues I'm having with my 73 Valiant. It has power brakes, front disc and 10 in drums in the rear. Decided to change the booster last week and discovered a leak in the rear seal on the master cylinder has a leak as it was leaking into the booster. I purchased myself a new unit from rock auto made by Cardone. Put it on a vise and bench bleed it. After spending a good amount of time on it I could not get the smaller section of the reservoir to stop shooting fluid from one of the holes could not tell where this air, if thats what it is, is coming from. I installed it on the car, blead the brakes drove it for a bit and every time I hit the brakes the oil light would come on and go off, see video below. Also while driving the pedal eventually became soft and pedal was almost to the floor before it started engaging. Now I do not have an oil light since the sender is gone and I rune a Oil pressure gauge. Its weird as it only started today after messing with the master. When I got back to check levels it sounded like the cap build pressure when I started to take the hold down off the master, it hissed. The level lowered in the small side and raised in the big side. Took the master of, redid the bench bleed, re blead the brakes same issue. Now I put the old one back on for now, chalking this up to a bad master out of the box. Old one bench blead, blead the brakes, and it seemed to do the oil light thing like the new one did, but seemed to stop after I added flued almost to the top. Before I filled it to the top it did the same issue with the fluid level, they where both the same level, drove it and checked, smaller side was lower and bigger side had more, filled them higher now it seems like some fluid is spilling out of the cap. Here's some pictures: Here is the issue with the oil light, odd, but after reading how the oil, and brake light is wired the similar, could this be something related to the proportioning valve? Here is the change in the fluid level after driving, both sides started at 3/4 full then the levels changed, the new master did this, and the old one (pictured) is doing the same. Master full to the top spills out: Here was the New master on the car, after bench bleeding for a long time using the fittings with hoses kit. Any ideas on the light? Prop valve? Is the fluid coming out of the master mean there is still air in there?