I understand what the anit-drainback oil filters do, and I also understand that most oil filters come with anti-drainback valves. I've heard that the OEM filters and the Mann filters are properly equipt with anti-drainback valves, but I also know that Fram filters also contain an anti-drainback valve. I now because I changed my oil yersterday and saw the valve.

But why the fixation on this valve?

Here is why I ask.

On a Honda, or a Toyota, or a Mazda, or, as with most cars, the oil filter sits on the side of the block. When you shut off the engine, if your oil filter does not have an anti-drainback valve, most of the oil in the filter will drain back into the engine's sump, leaving only minor amounts in the oil filter. The next time you start your car, your engined has to fill up the oil filter before it ever starts pumping oil to the rest of your engine. A bad scene.

But with the 850, where the oil filter is mounted upside down, practically below the engine's sump, why is it necessary to have an anti-drainback valve?

If the oil filter was mounted horizontally, or even right-side up (with the screw-on at the bottom of the filter), then I could understand. But with the filter being mounted upside down, what is the use of an anti-drainback valve?

Siphon effect?

Someone tell me why this is an issue on an 850.

I think that drainback is a bigger issue than from the filter body itself.

Since the filter is at the bottom of the system, there must be several oil passages above the filter. A drainback valve could possibly keep these passages full of oil.
--
3 8s & 2 7s 725,000 miles total

Older small block GM V8 motors also have a vertically mounted filter. The OEM filter does not even have an anti-drain back valve.
--
1999 S70 T5

Dear Ken,

I have been a Volvo owners for many years.

This is the answer:

Mann-Hummel is the leading mfg of filters (air, oil, fuel, cabin etc.). They are the OEM supplier for most of these European cars (MB, BMW, SAAB, Volvo, Porsche etc.).
http://www.mann-hummel.com/

But here is the key: Volvo has been using the same Oil Filter since 1964 on the very first Volvo's in the 1960's:
444-544, 120-130, 1800, 140-160, 200, 700, 900

I used to have 1991 240 and it is the same OF as my current V70.
However, on the 240 the OF is side-monuted and therefore Anti-drain back valve makes sense.

When Volvo designed the 850 series in the 1990's, for part inventory and simplicity reasons they used the same OF, even though the filter is mounted below the engine sump. No special reasons, they just want to use the same old stuff that is proven to work well in their cars.


cn
1998 V70 34K miles

Ken,

When Volvo design it 850 series. They were actually a cash trapped company. Dealing with new vendor(s) or new design actually made volvo looks silly. They used back the damm old part which was proven good. Oil filter was a good example. After all, with valve or not don't make any different for 850. Company bottom line was more important.

You are right, valve may not be necessary on 850. But it certainly makes a big different for designer.

Hope I'm answered you right.

As far as I know the fixation is on the RWD L4 Volvos. I mean, do the newer style cartridges have an ADB system?

And Fram had/has the worst ADB valve which doesn't hold the oil in the filter...hence the rap against Fram.
--
www.fidalgo.net/~brook4

when oil drains back, it is not only oil that drains back but all the stuff the you have filtered. it is not only a question of getting oil to all engine parts asap but also making sure that all the dirt filtered do not get reintroduced into the engine via backflow....

Agreed, however, as I said, the orientation and placement of the 850 filter makes drainback impossible.

In other words, if the filter were mounted in such a way that oil drained from it when the car is shut off, then I'd say you have a point. But the way that the filter is oriented, it will naturally never drain back.

If I'm missing something, please let me know.

it is just the nature of how liquids/fluids behave. having that extra protection is (definitely) not going to do your car any harm. the very purpose of your installing a filter in the system is to trap/separate solid contaminants and to CONTAIN them (inside the filter canister as much as possible). the best way to do this is to make the oil flow in one and only one direction.....hence, the anti-drainback gizmo.

But no manufacturer is going to make separate-but-otherwise-identical filters for cars that may or may not have a built in below-the-sump advantage. Cheaper to build it into every filter (or none).

Below the sump positioning wouldn't prevent the reintroduction of contaminants however. Otherwise, the minute the filter were pressurized the contaminated oil would run out any unchecked escape route and into places where you don't want it. Better to keep it trapped behind the filtration barriers.
--
David \\ (98 S70 T5SE Black, misc mods (mostly lighting), red calipers) (92 940GLE)

Perhaps the mechanics of the anti-drain valve are also part
of the by-pass valve so both functions are met using the same
(or related parts)? Just a thought since I've never ripped
open a filter to see how those work.

I'd also bet that the manufacturer wants to sell the same filter
to makes other then Volvo and some of those may vehicles
might use side mounted filters.