Anti Drain Back Valve or Not?

[Bamaro]

Originally Posted By: Shannow
Originally Posted By: SteveSRT8
take an empty soda bottle. Fill with water.

Now invert that bottle in a pail of water. Pull it out right up to the tip of the neck without pulling it all the way out of the water.

No water comes out of the soda bottle.

Anyone get it?


Take an empty soda bottle, and two pieces of hose.

place the hoses so that one is sticking say a foot above the bottle, and the other, out of the neck, and back down to say 6" below the bottom of the bottle.

We'll call hose 1 the oil gallery, and hose 2 the pick-up.

Fill the lot with water, and watch what happens...hose 1, the gallery empties.

bottle (filter) syphons down to the level that hose 2 penetrates, so down to the level of the threaded nipple for the filter mount.

Not as empty as the inverted filter, but it still drains back.

But there are no hoses going in or out of the filter.

 

[sunfire]

ADBV also prevents debris caught by the element (no matter the orientation) from being washed back into the pan. Flow should only go one way. Reverse flow would wash out the debris caught by the filter.

 

[Garak]

Originally Posted By: Bamaro
But there are no hoses going in or out of the filter.


But there is a fluid circuit, regardless of whether there are visible hoses or not. That, I believe, was the point being made. If it's thread side up and low enough, it's not an issue (i.e. the Chevy small blocks).

 

[tommygunn]

The oil circuit in a car is an open system. Without an ADBV it'll naturally try to reach equilibrium.

In this case, fluid will siphon, be it through galleys, tubes, pipes, passages or whatever, to the lowest point in the system. Its just physics.

You're better off with an ADBV if you can get it but if it didn't need one in the first place, I wouldn't fret.

Unless your oil filter is at the lowest point fluid will try to back out from it any way it can as the galleys supplying the filter cause hydraulic pressure due to gravity, pulling fluid out.

The only way to prevent this is to have every oil passage filled with air because it won't try to drain down through the engine. If you fill a vertically mounted filter with oil and hook it to an engine block, nothing will drain sure, but when there is oil filling the passages it'll want to pull down to the pan, and it'll naturally siphon from every area its attached to.

 

[Shannow]

Originally Posted By: Bamaro
But there are no hoses going in or out of the filter.


Not many soda bottles either.

ADBVs exist because designers want the suction "tube", the filter body, and the oil "galleries" to be full at the point where you turn the key.

If they didn't work, and we've all had cases where they have failed or been faulty and noticed the difference, they wouldn't be there, adding 3c to the manufacturing cost of the filter.

 

[Bamaro]

Originally Posted By: Garak
Originally Posted By: Bamaro
But there are no hoses going in or out of the filter.


But there is a fluid circuit, regardless of whether there are visible hoses or not. That, I believe, was the point being made. If it's thread side up and low enough, it's not an issue (i.e. the Chevy small blocks).


You cant have a siphon without a hose/tube etc

 

[Shannow]

Wherever you have fluid filled passages (whether they are metal, concrete, rubber, or glass), at different elevations, then you have a siphon.

An engine's pickup tube, and oil galleries form exactly that.