Is an anti-drainback valve needed in a filter that's mounded vertically?
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Propflux01
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No.
Only if you drove the truck upside-down. On the old Mazda RX-7's, the filter was mounted in an "upright" position (holes facing down) on top of the block, so oil would have every incentive in the world to flow out of the filter and back down into the engine, draining the filter and creating a pressure lag at start-up. With a filter in a "pendant" position down low on the engine, the oil would have to flow UP from a low spot for the ADBV to have any relevance, and of course, that's not going to happen.
[ November 20, 2003, 11:57 PM: Message edited by: TC ]
[ November 20, 2003, 11:57 PM: Message edited by: TC ]
Patman
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It is still beneficial to have an ADBV on a verticl mount filter though, as it keeps the oil directly above the filter from draining back to the pan on shutdown. This is why GM now uses oil filters with antidrainback valves on all it's vehicles, even those with vertical mounts.
What Patman said. It absolutely needs an ADV. Watch your oil pressure to see how long it takes to come up after sitting overnight or longer. If it takes longer than 2 seconds the oil is leaking down out of the cam and rocker galleries and having to be refilled to them. Usually lifter noise can be heard if the no adv is used also as it takes a long time for collapsed lifters to get refilled if they leak down. You can see the effect if you change your own oil. After draining the pan completely, leave the plug out and loosen the oil filter. All the excess oil that spills out was up there somewhere, ready to lube up the engine upon startup. I say leave the pan plug out because I also see a gout of oil out the pan when I loosen the filter on my 4.3 Chevy, I guess this is leaking back through the pump when the adv seal is broken.
Think of the ADBV as a "one-way" valve, like Patman said above, it not only holds oil in the filter (a given if it is in the "pendant" position), but it also holds any oil that is possible to be held prior to (actually after) the filter as well.
It is a good thing all around in a hydraulic sense.
It is a good thing all around in a hydraulic sense.
I agree with these posts that an ADBV can pretty much only be a GOOD thing -- I see little or no drawbacks to them for pretty much any application. Also, filters mounted on their side would normally need one as well since they'll "spill" just as the upright RX-7 filter would (above).
Having an ADBV on your particular engine will prevent oil in the upper channels from draining out, as Patman and others pointed out, so this is certainly a benefit. So I stand corrected on that. But you can visualize a filter in a pendant position as an upright teacup full of oil -- there's no way it can drain once it's full since the "column of air" above it could never purge out the oil. So adding an ADBV in that arrangement will only prevent the channels from draining, but have no effect on the filter draining. In short, an ADBV in your application is beneficial, but not critical. But yes, the other posters got it right.
Having an ADBV on your particular engine will prevent oil in the upper channels from draining out, as Patman and others pointed out, so this is certainly a benefit. So I stand corrected on that. But you can visualize a filter in a pendant position as an upright teacup full of oil -- there's no way it can drain once it's full since the "column of air" above it could never purge out the oil. So adding an ADBV in that arrangement will only prevent the channels from draining, but have no effect on the filter draining. In short, an ADBV in your application is beneficial, but not critical. But yes, the other posters got it right.
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