Anti Drain Back Valve

[Turbo Dog]

Can somebody explain to me what it looks like? Some filters have a large coil spring that I was told is the anti drain back valve. You can see it if you look inside the filter. However, the PF47 and PF52 don't have it. All filters seem to have a rubber grommet on the inside that covers the holes that go around the rim of the filter. I was also told that is evidence of the valve. One mechanic put a NAPA gold filter on my car. It has the rubber grommet. I called NAPA and they said it does not have the valve. So, what does this valve look like? BTW, I immediately removed the NAPA filter and put on a PF47.

 

[tom h]

The correct style of oil filters for the Buick is, WITH AntiDrainback Valve and NO built-in bypass valve.

The Buick bypass valve is in the filter adapter or base, so the filter itself doesn't require an internal bypass. Most Fords, for exmpl, are designed for a bypass in the filter itself.

The AntiDrainback Valve (as used on GM) is usually little more than a flexible rubber flap behind the outermost row of small holes on the filter. The PF52 definitely does have an AD Valve (haven't used the smaller PF47 in a long time, don't recall what it has).

It's common to do a "blow test" to verify the AD valve is working well. Pucker up, then blow hard thru the center big hole of a new clean filter. Very little air will pass thru a properly working AD Valve.

Lately, the Delco PF52s seem to be a a bit erratic on the quality of their AD Valve. Purolator seems more consistent; I've never had a weak AD Valve from them..

 

[Turbo Dog]

Thanks Tom H. At Speed Lube, every filter we looked at had the rubber piece. So did the NAPA filter that I removed, even though the NAPA guy said it did not have the valve. Would anybody know, then, what that coil spring was for?

 

[Richard Inglett]

NAPA Filter

The NAPA filter is made by Wicks and it does have an anti-drainback valve. Therefore, wouldn't worry.

 

[motorhead]

I just bought a 1/2 dozen long Fram (3798 IIRC) filters and I blew into one... and NOTHING came out. It is really hard bringing yourself to blow into something in front of a group out guys at the parts store.

You can see the rubber flap.

HTH,