Wix/Napa Gold Filter - Bypass Valve Design

[SuperBusa]

Can someone explain exactly how the filter bypass valve works on a Wix or Napa Gold filter. It's a unit that is placed at the base of the filter. You can see it in the link below ... click on it in the exploded view, and it will expand the photo. I can't tell by looking at it how it actually works.

http://www.wixfilters.com/productinformation/index.html

 

[labman]

Click on the little doodad at the top to enlarge it. It is a spring. When the pressure get too high, the spring compresses allowing it to push the whole works away from the base plate and let oil flow between the element and base plate. It is a common design. Champ used it a lot before the Ecore, and I think Purolator did too.

 

[Pete C.]

Labman you're close but don't get the cigar, when the Delta P exceeds the designed spring pressure. The higher pressure oil pushes against the black nitrile gasket that you can see. This happens on the side of the valve with the many small 3/32" dia holes. This action forces the valve to open and create a flow path directly from the main, baseplate, inlet holes to the filters outlet. Whatever the amount of oil, that is being bypassed, is, that oil never flows past the filter media. Bypasses rarely ever see full pump outlet flow. Well at least not in a properly maintained engine. And act a lot like a metering valve. Allowing the "over pressure" to escape back into the engine while allowing the rest of the oil to pass through the element. Yes it is thoretically "dirty oil" but at least it is still lubricating oil.

 

[G-MAN]

The spring loaded bypass valve is all contained in that small metal object that is between the orange ADBV and the filter end cap. If the pressure differential becomes great enough that it's easier for the oil flow to open that valve rather than go through the element, that's what happens, and the flow partially bypasses the element, goes directly through that valve, and back out the filter (essentially doing a 180 turn in the process).

The spring at the bottom of the can has nothing to do with it. That is there strictly to hold the filter element in place by keeping it pressed against the base plate.

 

[Gary Allan]

Quote:
That is there strictly to hold the filter element in place by keeping it pressed against the base plate.


Yes. If you think about it, the entire feed side of the filter is subjected to the same pressure. Only the bypass valve can have the floor fall out from under it since it's the only element that sees the center well's (reduced) pressure.

 

[labman]

I guess I didn't have that right. I would still like a little more explanation of how it works. Wix depends on a rubber gasket for its bypass? Wasn't the rubber bypass a big objection to the Ecore?

 

[SuperBusa]

Here's a link with some good shots of opened filters ... the NAPA Gold being one of them that shows and talks about the bypass vavle some.

http://www.peterverdonedesigns.com/oilfilter2.htm

From the looks of it (valve on the right), WIX type the bypass valve is similar to an anti-drain back valve, but it has a spring loaded flapper ((black rubber flapper behind the holes). When the flapper opens at it's DeltaP setting, the oil simply goes trough all those holes and then directly into the center core as others have said. Wonder if that rubber flapper is also silicone? ... and if not, should it be for better longevity.

Notice the rubber flapper overhang on the inside diameter?

 

[Pete C.]

Originally Posted By: SuperBusa
Here's a link with some good shots of opened filters ... the NAPA Gold being one of them that shows and talks about the bypass vavle some.

From the looks of it (valve on the right), WIX type the bypass valve is similar to an anti-drain back valve, but it has a spring loaded flapper ((black rubber flapper behind the holes). When the flapper opens at it's DeltaP setting, the oil simply goes trough all those holes and then directly into the center core as others have said. Wonder if that rubber flapper is also silicone? ... and if not, should it be for better longevity.

Notice the rubber flapper overhang on the inside diameter?


You are correct sir. It The gasket in the Wix valve is nitrile because of most auto makers OCI's. Hate to say it but management hates >4k OCI's. they wish everybody did

The end of that valve with the holes goes towards the baseplate. In the applications requiring an ADV, it goes around the neck(threaded part)of the baseplate and the UPFRONT BYPASS valve fits into a grove in the ADV and then the element slides around the other end of the bypass valve. The whole stack is held in place with the coil spring that is compressed between the element and the can.

 

[SuperBusa]

Originally Posted By: Pete C.

The end of that valve with the holes goes towards the baseplate. In the applications requiring an ADV, it goes around the neck(threaded part)of the baseplate and the UPFRONT BYPASS valve fits into a grove in the ADV and then the element slides around the other end of the bypass valve. The whole stack is held in place with the coil spring that is compressed between the element and the can.


How much filter element length is lost from using a bypass valve like Wix uses? I wouldn't think much, but it must cut down on the element's length some.

 

[Pete C.]

Not one little silly millimeter. The filters are designed to have the upfront valve in them.

 

[SuperBusa]

Originally Posted By: Pete C.
Not one little silly millimeter. The filters are designed to have the upfront valve in them.


I realized that after I looked closer on how it mates up with the filter element, and how short the actual valve piece is. They stuck the spring protrusion up inside the core so it doesn't take up any filter length - nice design.