Quote:
Originally Posted by Y-Blockhead
There is a new video on YouTube stating what is written above and it is simply not true and there is no need to drill out the valve.
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I saw that video and had a similar reaction.
I think people confuse the anti-drainback valve, which is the silicone membrane that you can see inside the ring of holes around the filter and which people sometimes recommend puncturing, with the bypass valve, which is a little spring way in the back of the filter. The bypass valve is the one that has the PSI rating of 8 or 13 or whatever. It opens only if the pressure inside the filter exceeds that rating. This is useful when the engine is cold in order to get oil to the engine quickly; a Model A oil pump can easily pressurize cold oil above the PSI rating of normal bypass valves. Otherwise the bypass stays closed and oil flows through the filter media, past the ADV, and back into the engine. The ADV has no PSI rating, it opens at any positive pressure at all.
I have no idea where this "check valve" terminology came from or why people got it into their heads to drill holes in perfectly good filters.