Originally Posted By: Garak
Originally Posted By: Newtonville
I know the bypass and adbv are different, and even know what they are. A GM engine without adbv in filter, originally equipped/spec'd, like I said before, should have a check valve in the engine. If car has filter adbv, it has no need for engine valve. Have seen it explained in a repair manual, and why I conclude it here.
I would say the manual you read is dead wrong. It wouldn't be the first time a repair manual was totally out to lunch. I'd also ask for your source. GM often uses bypass valves in the engine, rather than the filter.
Considering the way the ADBV works and its purpose, I would suggest that it would technically be possible to put it in the engine, but it would be a logistical and maintenance nightmare. For proper sealing, one would need to use something like nitrile or silicone (i.e. what's in filter ADBVs). Those things have a rather short service life, and having it in the engine would be a nightmare for maintenance, which would increase maintenance costs or simply be neglected.
The old Chevy small blocks, for instance, had no use for an ADBV. The filter was thread side up. Unless you parked the car upside down, the oil could not drain out of the filter. If the oil cannot DRAIN BACK from the filter, the anti-DRAIN BACK valve is redundant.
The thread up filters are the way to go, from a design perspective. No ADBV means one less part, which means one less potential for failure, and also one less item to cost money. Oil follows the laws of gravity, so instead of devising something to fight gravity, simply let it be your friend and do the job for you.
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Stockel is author, auto repair textbook, and it's correct. Check valves don't need to be rubber. There have been lots of explanations above, a lot of time spent, apparently wasted time. Chev isn't the only make with thread up. Ford Toyota many others have it on very common models, with adbvs. Various makes have/had no bypass valve in filter but in engine.