Which Mann oil filter?

[erdonline]

I have two different Mann oil filters on my shelf and am ready to chage my oil in both my 1.9 and my 2.1 Vanagons. I know that they need the anti-drainback/check valve. I thought that was what I was seeing just under the rim of one of them- the W719/5. But one online source lists W719/12 as the correct one for all water-cooled Vanagons, and there's nothing visible inside like the 719/5. The 719/12 looks more like an ordinary Fram. So which one is the right one, and should I be able to see the check valve? What is that thing that I'm seeing in the 719/5?

Thanks,
Ed in CT

[erdonline]

OK, any ideas here? I've searched past posts on the subject but have had no luck. It seems Van-Cafe sells the W719/12, so I'll assume that's the right one, but I'm just wondering what I'm seeing in the 719/5 just under the threaded end. Is is a by-pass valve, and not the anti-drainback valve? Frank on the Vanagon mailing list described what the anti-drainback valve should look like, but that's not what I'm seeing on the 719/12.

Anyone?

Thanks,
Ed in CT

[erdonline]

Some more info from someone on another list has helped me a little, but has also prompted more questions.

I see the anti-drainback flap on the W719/12. But I also see something similar on a Fram and an STP that I have as well. I thought the idea behind using a Mann or Mahle was that they have the anti-drainback valve and the cheap ones don't. So what is it that I'm seeing on the Fram and STP?

Where's the oil filter expert here?

Thanks,
Ed

[tencentlife]

Ed, I'm no expert, and the plethora of products on the market can be overwhelming, but this is one of those many subjects where in the absence of accurate info, uninformed speculation fills the void. A few pics and explanations might clear things up a bit.

Here's the deal: nearly any spin-on oil filter sold today of any brand or size has both bypass and anti-drainback valves built in. It's just standard for the industry. There are exceptions, but they are generally for special applications. But as you'd expect, how these things are accomplished differs.

You've just done your own little survey, and found that out for yourself. If someone went thru every OF on the shelves at a FLAPS, you would find very few that don't have the anti-drainback valve (ADBV), which is easy to see thru the openings of the endplate.

And here's the funny part: people sweat about whether there's an ADBV, but the question is doubly moot; nearly every filter you can buy has one anyway, and it's only needed if your filter lives on its side or upside down, as they do on many engines. The way the Type4 and wbx hang their filters, the ADBV is superfluous. I've considered this at length, and don't see how oil settling can siphon out the contents of the filter. The physics of that just don't work. And every time I've removed a filter that is situated this way, it has been overflowing with oil no matter how long it has sat. But it doesn't matter, because if you buy a spin-on filter, chances are you're going to get an ADBV whether you need it or not.

I just went out and took some pics of a Mann I cut open awhile back, so everyone can see what the insides look like. The ADBV in a 719/12 looks like this:

You can see it's just a silicone, EPDM, or other soft rubber disc that acts as a low-restriction check valve right below the inlet openings of the filter:

But the Mann bypass valve can't be seen from just looking at the filter, because it lives in the bottom endcap of the element.

This is the Mann element taken out and inverted. Its bypass valve is built into the element cartridge. Here I'm depressing the bypass valve's little rubber disc against its counterspring:

Flow thru the element is from outside-in, up and out thru the center spigot. The pleated element is supported thru its center by a perforated metal sleeve so it won't collapse. When pressure is above the valve's opening pressure, it forces the little valve at the base of the element casing open and allows a portion of the flow to bypass the element. If it didn't, when the medium can't allow all the oil to flow thru, the element pleats would be collapsed and tear away at the ends, where they are joined to the element casing. Then there would be unfiltered flow at all times. The filter's outer casing can also rupture from the high pressure if it isn't controlled.

I've never heard of a pleated-element spin-on filter that does not have a bypass valve. Of course there are some made, once again for specific applications. As you can see, it's pretty important to have one because otherwise we would see many burst filter casings, and even the best-built elements would be torn thru on the first startup if they couldn't let some of the cold 90+psi oil go around the element. To obviate a bypass valve in a full-flow filter it could have a very open media that allows high flow of cold oil, but that would be let a lot of small particles go by. With a medium of a given area, resistance to flow is in direct proportion to filtration efficacy. So you could increase the size of the media, but to present very low restriction under all operating conditions the filter's size would become unwieldy. So the compromise in design is to have more medium area folded up and packed into a small casing, and protect it with bypass capability.

In fact, I looked up these filters on Manns website, and the main difference between the 719/5 and /12 is that the /5 has a 2.5 bar bypass, while the /12's is 1bar. That means the correct filter for the wbx allows oil to begin bypassing the element at only 15psi! With a reasonably tight engine at highway rpms, where it should raise at least 35psi OP, that valve would be fully open and good portion of the oil would not be being filtered at all! So much for full-flow filtering.

By the way, I have on my bench right next to that Mann a slightly-used FRAM Tough Guard cut open. It has the same features, anti drainback and bypass valve. It differs mainly in the construction of the pleated element and the bypass valve:

Compare the Mann element casing above to the Fram element. The Mann has the pleated media bonded to a metal casing, whereas the Fram's media is glued to cardboard endcaps. Both, as I said, have a perforated metal sleeve inside that supports the media against collapse. It would be tempting to say that the glued construction is a very poor way to build this, but provided factory quality control is decent, it's not much of an issue so long as the bypass valve does its job of keeping strain on the media within limits. But, QC and the methods to do this do vary from source to source. Both types of element construction are common, the metal type being moreso judging by some of the surveys I've seen.

You can see that the Fram bypass is separate from the element and instead housed in the spring riser that sits in the base of the outer casing (the Mann has a similar riser that I didn't show. These lay in the bottom of the casing and keep the element pushed up against the endcap). Unlike the Mann, the Fram has a filter screen around its bypass valve, so it does some filtering (albeit quite coarse) when in bypass mode, whereas the Mann just lets the bypass flow go by unimpeded.

Other filters bypass by having a coil spring under the element instead of the leaf-spring riser. When pressure is high, the entire element is pushed down away from the endcap and allows flow to bypass the element.

With a flashlight, you could probably see the bypass valve thru the center opening of most filters, except for the ones that spring-load the element itself.

Now, this gets me to the operating difference of different filters, and the big question around here: why do people who get an oil pressure warning with a hot-running wbx report that switching to the Mann filter makes them get the warning less often, or makes it stop altogether?

Well, it's not magic. Allowing that the inlet holes present more than adequate flow area, and the drainback diaphragm doesn't restrict flow around it, both of which are givens with most of the available designs, there's only three factors here that influence the volume of oil that can transit the filter with a given oil weight, temp, and pressure: fineness of filter medium (average pore size), surface area of the media, and the opening pressure of the bypass valve, or combinations of these three.

Here are two links to one of many places on the internet where you can see benchtop studies comparing a variety of spin-on filters that are on the market:
http://www.knizefamily.net/minimopar/oilfilters/index.html
http://www.knizefamily.net/minimopar/oilfilters/german.html

The second one includes some German filters. Parts of the comparisons, however, are pretty dated, and not only the specifications but the actual sources of these filters could have changed since then.

But, in that study, the Mann 719/5, which on the Mann website is identical to the /12 in overall canister size and mounting type so presumably has a similar-sized element inside, has 285 sq.inches of medium area. The Fram Tough Guard (not Extra Guard!) has 248. Not a big difference in area, but we don't know the relative avarage pore sizes of their media, and we can't compare the opening pressures of their bypass valves.

The main thing to keep in mind, though, in that oft-reported scenario with the warning buzzer is that the real problem is that the OP is marginal, not that the wrong filter is being used. Engines with healthy oil pressure are able to work past the slightly higher restriction caused by a filter with smaller media area, or finer media, or both.

If you take a look at the Knize comparison and follow his links, your head will swim with the myriad details of measurable aspects of various filters, and be surprised at how many appear to be exactly the same products made in the same factories but relabelled. Unfortunately, few of the comparisons on the web are actual studies, as it would take deep pockets to run filtration and flow analysis on these products. They are for the most part analysed under SAE specifications, but the tests are paid for by the manufacturers and the results are closely held. In addition, few on the web include non-American-made filters in their comparisons.

Anyway, if you want to waste a few hours of your life, explore the links above. Here's the Mann website as well:

http://www.mann-hummel.com/mf_prodkata_usa/index.h...kToPage=11
_________________
Shop for unique and useful Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
also available at VanCafe.com!

Please don't PM here, I will not reply.

Experience is death to doctrine.

[erdonline]

Chris-

Thanks for that excellent, informative reply. I tried a few times to access the Mann website myself, but it times out. Maybe it's something on my ISP or my computer.

Let me summarize a few of the points you made and see if I've got this right-

Vanagon owners shouldn't be worried about anti-drainback valves because the filter is mounted mostly upright anyway. And just because we don't see the ADBV at the top doesn't mean that it's not there.

The other difference that many Vanagon owners worry about is the bypass valve. The correct filter allows oil to bypass the filter at a very low pressure, so that's why switching from a Fram or STP to the Mann makes the OP light go off if it were on- oil is now bypassing the filter.

Thanks to your post, I think I've got it!

Here's a quote from Dennis Haynes, from the Vanagon mailing list, who answered my post on that list:

"The difference is the bypass not anti drain back valve. Both do have the
flap type anti drain back valve on top. If you look at the oil filter
adapter on most in VW line you will see a ball. The ball is held in place
by a spring. This is the bypass valve. The Water boxer does not have this
so it has to be in the filter. Most after market filter companies
incorporate this feature. That is why most aftermarket uses the same
filter number for both applications."

One other thing to note: I found a cross-reference list on germanfilters.com. It lists the Fram cross reference to the Mann W719/12 as a PH2991 or PH 3600. I could only find the latter online. Other books in the auto parts stores list the PH2870A. This makes me wonder if the by-pass valve of the 3600 or 2991 is closer in specs to the correct Mann one than the 2870A, or if the 2870A.

Thanks again for the info.

Ed in CT

[Perales]

Sticky nomination!
_________________
-- 1987 Westfalia automatic (Captain Vino)

[tencentlife]

[Hippie]

[randywebb]

10cent - what filter do you use yourself?
_________________
1986 2.1L Westy 2wd Auto Trans.

[andk5591]

FYI - (general oil filter info) I have done quite a bit of research on filters for ACVW and NAPA Golds are a REALLY good filter - tests that I have seen compared to Mann, Bosch etc, is eye opening.
_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them...

[RCB]

Wix is the manufacturer of the Napa Gold oil filters and I found them to be very good filters; also found out that the Wix #49551521 is the exact same filter without the fancy paint on it. Last bunch I bought was from Rock Auto, not sure if the sale is still on but it was a real good deal.

The Wix web-site is really informative too.

[tencentlife]

[Hippie]

Yes, it seems once the problem is solved they are gone, daddy, gone.
I agree There shouldn't be enough pressure drop @ operating temperature to let the bypass open at all with the correct filter (a normal off the shelf filter that is).

ACVWs are odd that they regulate oil pressure after the filter rather than at the pump, too, and I think that causes a lot of bulged or blown filter complaints when people don't use a filter with a correct bypass in an after market oil filter add-on. The TIV engines, I believe have a bypass built into the filter mount like many GMs.

[tencentlife]

Yes, that's right about the Type4, it has that ball-valve you can see as part of the filter mount. No idea what the bypass pressure is for that, though, it would be interesting to know.
_________________
Shop for unique and useful Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
also available at VanCafe.com!

Please don't PM here, I will not reply.

Experience is death to doctrine.

[Hippie]

Yes it would be nice to know the setting. I bet it's fairly high because we used to run a lot of straight weight SAE40 and like that in even temporarily cold weather.
It could be tested, I guess, but with some difficulty. I have a remote filter on my T1 Bus, and have to remember to use a bypass type filter, and some OEM direct cross reference for the T4 have them, and some don't because they are also spec'ed for other applications.
I usually run a Wix 51516, or the larger 51521 or K&N equivalents.

It's nice to find another oil filter "nerd" to talk to.

[tencentlife]

Ha, funny, filter nerds.

Well you wouldn't know if the T4 bypass valve was opening or not under normal use. You could isolate it and run a test, I supose, it would be easiest on a block on the bench.

As for spin-ons, you can find the bypass spec on any filter commonly available, just need the part number. FRAM's cross-reference service got upgraded a couple years ago and it gives all those details, plus makes it easy to tell who's making whose fiilters. Manns don't come up in the FRAM cross-ref but Mann's website has plenty of tech details on all their models. Just have to look them up, but gotta have a P/N first.

I like the Trasko myself, been using it for ages.
_________________
Shop for unique and useful Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
also available at VanCafe.com!

Please don't PM here, I will not reply.

Experience is death to doctrine.

[Wildthings]

It would be easy enough to remove the filter adapter from a T4 engine and set up a jig to measure the opening pressure of the bypass.

The next time I pull a T4 engine down I just may eliminate the bypass, as its a point of potential failure. Since all of the filters I use have internal bypasses anyway it serves no purpose. On my T4's I just use Motorcraft FL1a's or FL300's or equivalents, either are readily available, with the FL1a being the most common filter out there.

[Hippie]

[Hippie]

[tencentlife]