Bypass location

[Jim Allen]

Originally Posted By: ZeeOSix
Originally Posted By: Jim Allen
Quote:
From ZeeOSix:From a "possible engine contamination during bypass event" perspective, the filter bypass valve built into the block is the best configuration, as it gives zero chance for any collected debris in the filter from entering the engine during a bypass event.


Good observation. We've been stepping over that very obvious point as we heatedly debate the position of the filter bypass. But we must also consider how the engine bypass works. In the case of my 6.9L diesel, the bypass is in the filter base, so when it bypasses, it bypasses into the outflow, so it's the same as if it was built into the filter.


In your 6.9L diesel, even though the engine's bypass valve is in the filter's base, it's still not in the filter at all (right? ... if I understand you correctly). Boils down to if the bypass filter is actually inside the oil filter or not.

Even an oil filter with a base end bypass, the valve is still inside the filter where debris is collected. With a base end bypass inside the filter, it's still possible depending on the filter's orientation to have debris flow through the bypass if it opens. Example I gave was using a filter with a base end bypass on a 4.0L V6 Tacoma engine which has the filter mounted perfectly base down. If the filter was so loaded up that debris fell out of the media and down on the base of the filter where the bypass valve was, upon cold start-up that debris could flow through the base end bypass valve and into the engine. But if the bypass was in the block, or in the filter mount, that debris couldn't flow through that bypass valve because the bypass valve is external to the oil filter.


Yep, you're right Zee. It will bypass unfiltered oil but it won't be washed off the filter element or the washout from inside the can. Didn't think it all the way through.

 

[Sayjac]

Originally Posted By: TallPaul
That was a "Service Engineer" who stated their lab testing finding. So it is front end and rear locations. Wow, that just does not sound like professional terminology.

Now the big question. Why do they have a front end bypass on any of them. If Ford requires it, why is Baldwin's FL1A (Baldwin B2) filter with it, but their FL400s (I don't have the Baldwin # on this) is without. Both are ford and both have front end bypass in Wix. Neither have front end bypass in Federated (Hastings made).

I agree, front and rear end discriptors for bypass doesn't cut it for me either. Dome end and thread or base end seems more appropriate for the bypass location.

As for Ford's preference for thread/base end, it was Gary Allan (rip) that used to say that Ford/Motorcraft is persnickety when it come to bypass placement. But, he also made the point that while base end is FoMoCo preferable, using an aftermarket filter with dome end doesn't void the warranty. And afaik, the the FL400S uses thread end bypass as shown in this thread. But, the interesting Motorcraft filter is the one discussed here recently the unique FL-1A which uses thread end bypass but a nitrile adbv rather than silicone.

After reading this board for some time, and being informed that bypass events are relatively rare and of short duration, I agree with Gary's (and others) general opinion that bypass location isn't a big deal one way or the other. OTOH, river_rat prefers base end bypass when the filter is oriented in a dome end down verticle position, obviously with the thought of a bypass event in mind.

 

[dickwells]

I believe so, however only when the valve is at the dome end is the oil washed over the accumulated dirt that drops off the filter and accumulates on the bottom side of the filter can. When the valve is at the thread end the oil comes in and immediately goes back out without exposure to the dirt or dirty element.

 

[TallPaul]

Well now I am having second thoughts about the dome end. My fords all have vertical or near vertical mount so the base plate is up. I noted that would cause any junk collected in the dome to blow into the engine upon bypass opening. My son then asked if there was any junk in the dome on the ones I had cut open. I don't recall any junk in the dome. So maybe it is a non issue.

Advantages of a back (dome end) bypass valve:

1) More media because the front end bypass takes a lot more space.
2) More options on upsizing the filter.

For the Mountaineer, I can get a filter that is 1.5 inches longer (5 and 3/8 inch long) if I don't have to have a front bypass. As it is, the FL820s for the Mountaineer gets pretty filled up (can't see light through the element) after 5000 miles.

But check this out at the Baldwin Filter Lookup Site.
If you plug in FL1A it gives you Baldwin B2 and if you click that open, it actually says "Front End By-Pass Valve." Nice! I'll run that on the Ranger if I have clearance (Ranger specs FL400s). I have been running FL1A size on the Aerostar 3.0 for 9 years and that also specs FL400s.

Oh, I cut open a Motorcraft FL820s today and the antidrainback valve has these big bumps on the back that help hold it against the input of the filter baseplate. That is a feature I don't recall seeing on other brand's antidrainback valves.

 

[Jim Allen]

Tallpaul: For you further consideration, the key element in this question is how often and how much the bypass opens. That's a question that has been difficult to get answered. We want absolutes and I've been told again and again, it's highly situational. The closest I can get from the filter people I have interviewed is that in normal circumstances, using the correct oil grade for the environment, bypass events are "infrequent," "of short duration" and not a 100% opening of the valve. As I discussed above, there are several things that can make bypass events more frequent. If your operational situation indicates that bypass events are going to be more common, then perhaps a base end (back end) bypass is more important.

 

[TallPaul]

Well I think base end meaning the plate with the threaded hole is called the front end. Anyways, here is more that the Baldwin engineer told me:

Quote:
Regardless of the location, the bypass only opens when the pressure differential between the dirty side and clean side reaches the set bypass rating. At that point, the filter should be changed regardless because it has enough contaminate to plug the media.


But how do you know when you reach that point? Maybe we need something like a turkey thermometer that the end pops up when it is at the right temp. So in a filter a pop up on the dome of the can indicates the bypass has started opening a lot? But doesn't the bypass open every cold winter start?

If one of us searches it out, Gary Allan did a whole lot of research on this including having oil pressure gauges mounted on his Jeep Cherokee both upstream and downstream of the filter. He made some conclusions regarding bypass opening events.

 

[dickwells]

Yes they are on about the same level, however the dome end bypass has the oil washing the lower side of the filter where crud accumulates while the base end bypass just has it come in and out without washing over the accumulated detritus.