Im not sure if this varies engine to engine, but is the bypass opened when the engine is cold started? Or is this in place so when you do an extended OCI, it will open when the media plugs up? Is the placement of the bypass valve THAT CRITICAL? Weather it be top or bottom?
How often does a oil filter go into bypass?
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IIRC, Gary Allan's testing revealed that at least in his particular engine, it only happens briefly when cold. I've had automotive engine design engineers tell me it happens more often than that, e.g. when near redline type RPMs. It may be the case that it's somewhat engine specific.
So is picking a filter depend on where the bypass valve is located, or doesn't it matter. In Ed White's article quoted below, there is mention of dirty oil being re ciculated, is this #@$%!?
Quote:
"Bypass (pressure relief) valve. Ford prefers to have the bypass valve at the base end of the filter. Many filter manufacturers prefer to place it at the dome end. The dome end location is cheaper and easier to manufacture. However, for filters with dome end bypass valves, if the filter goes into bypass mode, the oil will circulate past the dirty side of the filter before passing through the bypass valve, and back into the engine. I believe that this may result in the oil picking up additional contaminants and returning them to engine (besides not having been filtered at all). I prefer base end bypass valves. It is also important to have a bypass valve that opens at the correct pressure differential."
Quote:
"Bypass (pressure relief) valve. Ford prefers to have the bypass valve at the base end of the filter. Many filter manufacturers prefer to place it at the dome end. The dome end location is cheaper and easier to manufacture. However, for filters with dome end bypass valves, if the filter goes into bypass mode, the oil will circulate past the dirty side of the filter before passing through the bypass valve, and back into the engine. I believe that this may result in the oil picking up additional contaminants and returning them to engine (besides not having been filtered at all). I prefer base end bypass valves. It is also important to have a bypass valve that opens at the correct pressure differential."
Who is Ed White?
In any event, IIRC, Ford is the manufacturer that originally preferred baseplate located bypass valves for the reason stated above. This provides some evidence that bypass valves are engaged on a somewhat regular basis, at least on some engines.
In any event, IIRC, Ford is the manufacturer that originally preferred baseplate located bypass valves for the reason stated above. This provides some evidence that bypass valves are engaged on a somewhat regular basis, at least on some engines.
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In my reasoning, engines with a narrower span between cold and hot oil pressures are more likely to have the filter bypass. My cold pressures were 82 ..even at idle cold ..while hot idle could span from 55. Very high ceiling ..so to speak. Assuming the same volume, if the relief was @ 50 or 60 ...then I would be very near the relief with 20w-50 24/7.
My belief is that the bypass is only active where there is a difference between pump output and the flow to the engine. If there's no differential there ..there should be hardly any PSID. Next to nothing and less then next to nothing depending on visc.
When I get done with other distractions, I'll install my PSID gauge setup on my wife's jeep and put in 5w-40 oil. It's in relief 24/7 off of idle. I believe that it will be in bypass ..or at least at elevated PSID 24/7 that will vary with viscosity.
It this application the ceiling is very close to the operational lows. You're @42 psi at hot idle ..and 58 off idle (5w-40) 5w-20 is the only oil that fits 100% of the pump output through the engine after warmup. It runs around 51 ..even that thin oil is close to pushing it.
My belief is that the bypass is only active where there is a difference between pump output and the flow to the engine. If there's no differential there ..there should be hardly any PSID. Next to nothing and less then next to nothing depending on visc.
When I get done with other distractions, I'll install my PSID gauge setup on my wife's jeep and put in 5w-40 oil. It's in relief 24/7 off of idle. I believe that it will be in bypass ..or at least at elevated PSID 24/7 that will vary with viscosity.
It this application the ceiling is very close to the operational lows. You're @42 psi at hot idle ..and 58 off idle (5w-40) 5w-20 is the only oil that fits 100% of the pump output through the engine after warmup. It runs around 51 ..even that thin oil is close to pushing it.
Yeah he's posted around here a few times linking to his site.
I did a FL-820S study (no tear-downs) about the same time as Ed & wondered the same thing. Here was my conclusion:
Bypass valve location is better in the base especially if the filter got loaded and ran into bypass a lot. If filter goes into bypass only temporarily, such as start-up and occasional high revving, I don’t care about location since my application has the filter horizontal. (I would be concerned if filter is vertical with dome at the bottom.) I may care if I was severe duty or hard-driver but then I would then be more concerned about flow rate and bypass psi....Then again I may just do OCI at 3000 miles as recommended by Ford for sever duty.
Bypass valve location is better in the base especially if the filter got loaded and ran into bypass a lot. If filter goes into bypass only temporarily, such as start-up and occasional high revving, I don’t care about location since my application has the filter horizontal. (I would be concerned if filter is vertical with dome at the bottom.) I may care if I was severe duty or hard-driver but then I would then be more concerned about flow rate and bypass psi....Then again I may just do OCI at 3000 miles as recommended by Ford for sever duty.
With the bypass valve at the dome, wouldn't the bypassing oil "wash" some of the debris into the oil stream?
Sounds like similar circumstances to when a quife is produced.
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I'm lacking any kind of proof, but I don't think it would be a big concern. With the bypass open, the pressure difference between inlet and outlet is still exerted on the filter media, and there is still positive flow through the media, so I don't think much would escape from it.
Except in the rare case when the filter media is clogged and has no flow. Then the media can be "washed" and previously filtered out debris is free to travel through the bypass into the oil galleys to critical parts of the engine.
But by that time, it probably looks like this and you'd be happy if oil is still flowing at all:
37k On unknown filter. 1999 Dodge Van w/ 360 CID
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That would take either a very dirty engine ..or a very long time, imo. If a filter is in service for that long, I doubt that the bypassing oil is worth too much in terms of wear prevention.
You're probably right.
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Let me add one more thing to my rhetoric. I'm surely open to opposing points of view if they're reasonably supported (sensible). My point of view is constructed from my reasoning of observed data. Since I'm both the observer and the reasoner ..it's going to make sense to me. I'm merely constructing theory that supports the observations that appears, again in my view, to withstand reasonable challenge in the confines of what it implies under the qualified conditions. Beyond the limit of my observations ..there I'm over extending myself since I can only apply reasoning that makes sense in a different set of circumstances. I'm therefore using observed and reasoned events as a template for speculation on those situations not observed.
In can certainly see bypass ..or rather elevated PSID that may result in bypass ..at the upper limits of the operational limits of the engine (redline). There, pumping losses, that may be minor at more moderate speeds/upramp curves ..may come into play to a greater degree..as surely would "transitions". You've got a mass of oil moving and it may have effects when being yanked from one flow rate to another (as we observe with our garden hose when we oscillate the pistol grip and feel the slamming of the moving freight train try and expand the walls of the hose - and, conversely, if the valve is on the other end of the moving freight train ..the flow attempting to collapse the hose as it "wants" to continue to move at the same rate).
In can certainly see bypass ..or rather elevated PSID that may result in bypass ..at the upper limits of the operational limits of the engine (redline). There, pumping losses, that may be minor at more moderate speeds/upramp curves ..may come into play to a greater degree..as surely would "transitions". You've got a mass of oil moving and it may have effects when being yanked from one flow rate to another (as we observe with our garden hose when we oscillate the pistol grip and feel the slamming of the moving freight train try and expand the walls of the hose - and, conversely, if the valve is on the other end of the moving freight train ..the flow attempting to collapse the hose as it "wants" to continue to move at the same rate).
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