Oil Filter Anti-Drain Valve
Q: I am working on my all stock 77 "B". It came factory with the spin on oil filter adapter I'm thinking? Filter canister points up.
I don't remember how I came to the decision, but I'm using Wix PL20195 filter which is a little longer than the filter listed for the car. The filter is listed with a "drain back valve" just like the shorter one, but when it sits for a while, like our cars often do, the oil in the filter drains back into the motor, and it takes an inordinate amount of time to fill the filter back up, to get oil pressure. I'm always very careful to keep the rpm very low until I get pressure, but I don't like it. The question is do all filters drain back over time, or is a check valve or something missing from my car? I'm going to change back to the short filter to speed up the time it takes to get pressure, but was just wondering what the deal was.
A: The filter body points upward because there was no physical room for one to be installed in the traditional downward orientation. My 1980 is the same. I use the standard "Classic Gold" oil filter provided through Moss dealers. They too have an anti-drain back valve. I have near instantaneous oil pressure upon cold start --- even after letting the car sit for weeks.
The has a tube designed to hold the oil in a short filter. The longer filter drains down to the level of the tube and has to be refilled each time. That's why the short filters get instant pressure.
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