Filter By-Pass Design

[SuperBusa]

So I'm looking at the WIX/NAPA Gold filters and see they have the by-pass valve located in the base (threaded end) of the filter. With that type of design, and when there is a by-pass event, the oil totally by-passes the dirty outside area of the filter element and flow directly into the engine, thus cutting down the possibility of sending collected contaminates into the engine.

If the by-pass is placed in the end cap (most common design) of the filter, it's possible that trapped contaminates from the outside area of the element could flow into the engine.

I've never seen any tests done to determine if there is major difference in these two by-pass valve designs to validate that the common design (valve in end cap) is really that detrimental. I would think most of the contaminates are trapped deep down in the pleats and wouldn't shift around in a by-pass event. Also, even in by-pass mode, there would probably still be a slight flow through the pleats to help hold contaminated on the filtering element.

What's your viewpoint?

 

[another Todd]

It's called filter wash. The oil filters that manufacture their filters with the bypass at the sealed end say it is not an issue. Those who make it at the threaded end claim it can be. I prefer it on the threaded end, issue or not.

 

[Sayjac]

All I know is, on my sons 4.6L 05 Explorer, the Motorcraft filter with base end by-pass works best. No noise(rattle) at start up, and it's Ford recommended.

Motorcraft is a great bang for the buck, and for a Ford I don't see a need to use any other. JMO.

You might find this thread interesting.

https://bobistheoilguy.com/forums/threads/fram-cut-open.101107/

 

[Gary Allan]

I don't see it as too much of an issue. FoMoCo is pretty anal about it.

I don't think it's a "WHOOSH" through the bypass. I think it's got the same wall of identical back pressure/resistance to deal with. The same PSID will still be present across the media. There's nothing to stop the oil from going through the media. It's not like you're going from 15PSID and, when the bypass opens, you drop ZERO (although I imagine that there could be some modulation/fluttering going on - though it never occurred in any of my observations). You're going from 100% media throughput up to the point of bypass ..and, with the lion's share of PSID still being applied, there's no reason to think that flow stops.

 

[SuperBusa]

Originally Posted By: Gary Allan
I don't see it as too much of an issue. FoMoCo is pretty anal about it.

I don't think it's a "WHOOSH" through the bypass. I think it's got the same wall of identical back pressure/resistance to deal with. The same PSID will still be present across the media. There's nothing to stop the oil from going through the media. It's not like you're going from 15PSID and, when the bypass opens, you drop ZERO (although I imagine that there could be some modulation/fluttering going on - though it never occurred in any of my observations). You're going from 100% media throughput up to the point of bypass ..and, with the lion's share of PSID still being applied, there's no reason to think that flow stops.


Agreed ... that's how I see too. I imagine if the filer just packed full of contamination there might be more of a chance of contamination flowing through the bypass valve. But if the filter is changed regularly it probably isn't really a concern.

What's probably more important is that the by-pass is tight until it needs to open (no leakage) and that it does open at the right pressure.