School me on filter operation

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Sep 26, 2002
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Central Arkansastan
Got a friend that wanted me to change oil on his Harley. When I drained it, it had lots of metal shavings, looking not unlike that of light metallic paint. He was running a WIX 57148 filter. He asked me why there was stuff in the oil, that shouldn't the filter have taken that out, and the oil be relatively clearer. I couldn't give him an answer. So it got me thinking, am I looking at this wrong or ?

Now, the bypass pressure of this filter is 8 PSI. We hooked up a gauge to this engine and ran it till it got pretty hot. At 3k RPM oil pressure was 45 PSI, idle was 15PSI. Now is this filter even filtering at these pressures, or only under 8PSI? Or is the filter allowing 8PSI through, and the rest through its bypass, only partially filtering the oil? And if neither is the case, why did we see metal at all in the oil, instead of a clogged filter? WE cut the filter open, and it really doesn't show much of anything in it. It just seems to me, that I should have seen those particles in the filter, rather than the oil. And since I can see them, I will assume they are larger than 20 Microns. What am I missing here? Filter1.jpgFilter2.jpg
 
My understanding is that the bypass PSI relates only to pressure delta across the media of the filter. IE. if the filter media is totally plugged the pressure delta goes up and exceeds 8psi which opens the bypass to prevent starving the engine of oil.
 
isn't wix 99%@30-40 microns. That could be some of the issue. Get a fram TG or Pure 1 on that bike and see if you notice less particles.

It could have more wear if air cooled and potentially using less than 20w-50 that Harley recommends.
 
So the filter should be filtering oil all the time unless the element gets clogged, (over the 8PSI as you described) correct?
I believe so. Probably some more math and details that go into it but that's my basic understanding. There a Fleetguard guy on here that could probably dive into it for you but I don't recall his username.
 
My understanding is that the bypass PSI relates only to pressure delta across the media of the filter. IE. if the filter media is totally plugged the pressure delta goes up and exceeds 8psi which opens the bypass to prevent starving the engine of oil.
The most common time the bypass is used is probably at cold start in cold climates where forcing very thick oil through the filter will result in a large pressure drop, if you get to the poin where the bypass has come on because the filter is almost completely plugged, you have a much bigger problem on your hands.
 
isn't wix 99%@30-40 microns. That could be some of the issue. Get a fram TG or Pure 1 on that bike and see if you notice less particles.

It could have more wear if air cooled and potentially using less than 20w-50 that Harley recommends.
Regular Wix/Napa Gold are generally 95% @ 20 depending on the model.
 
The most common time the bypass is used is probably at cold start in cold climates where forcing very thick oil through the filter will result in a large pressure drop, if you get to the poin where the bypass has come on because the filter is almost completely plugged, you have a much bigger problem on your hands.
I would agree.
 
The bypass filter rating is the differential across the filter pleats. In your case if the differential pressure delta from the inlet side of the filter to the outlet side drop is 8PSI or more different, the bypass valve will begin opening.
Yup, this. The bypass pressure is the sensitivity to pressure drop across the media, the differential imposed by the restriction the media places on the system. Observed oil pressure, after the filter, is the result of the system's resistance to flow. If you have oil pressure gauges both before and after the filter, you can measure that differential. With hot oil, provided the media can flow sufficient volume that the engine remains the biggest restriction, the bypass should stay closed and drop across the media should be low.

However, there are situations where the differential (delta-P) will become elevated and when it reaches the trigger pressure, the valve will begin to open to allow some oil to bypass the media and reduce the delta-P.

With cold, thick oil, the media will flow less, which can result in the bypass cracking, allowing some oil to bypass the media, until the oil heats and thins. Of the different types of media, cellulose has the poorest flow per square inch.

Even hot, if there isn't enough surface area, or the media begins to plug up, at higher RPM with higher volume being moved by the pump, it's also possible for the bypass to crack open, allowing some oil to bypass the media.

With regards to the observations made, if the particulate is heavy enough to stay on the bottom of the crankcase and not end up going up the pick-up, it's never going to end up in the filter, you just flush it out with the oil change.
 
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Engine oil pressure and filter bypass pressure can't be compared.

The problem with the Harley and its metallic oil:
1. Engine a piece of junk, either assembled poorly at the factory or rebuilt horribly over and over somewhere else, or simply worn out.
2. Its modded excessively, which would require data to adjust oil grades, oil change intervals, filtering capability, oil cooling capability....
3. The oil chosen didn't match the engine well enough.
4. The interval chosen didn't match the driving style well enough
5. Filter media, where you can't see, is loading up too quickly. Filters trap within the media and not just on the outside.
6. Pathetic aftermarket box tune
7........... along with a million other possibilities

So, your concern with the filter has NOTHING TO DO with your metallic oil. Something else is going on.

Year/make/mileage/engine/mods/oil brand/grade/interval is a good start, along with some data like running oil pressure and temps..

If you can see the metallic shine in the oil, then you should consider a UOA to see what metals are coming up.

Punch the PN for info on that Wix filter. 5 micron nominal should yield a tolerable absolute micron rating with its synthetic media. This isn't your normal Wix car filter.
 
Yup, this. The bypass pressure is the sensitivity to pressure drop across the media, the differential imposed by the restriction the media places on the system. Observed oil pressure, after the filter, is the result of the system's resistance to flow. If you have oil pressure gauges both before and after the filter, you can measure that differential. With hot oil, provided the media can flow sufficient volume that the engine remains the biggest restriction, the bypass should stay closed and drop across the media should be low.

However, there are situations where the differential (delta-P) will become elevated and when it reaches the trigger pressure, the valve will being to open to allow some oil to bypass the media and reduce the delta-P.

With cold, thick oil, the media will flow less, which can result in the bypass cracking, allowing some oil to bypass the media, until the oil heats and thins. Of the different types of media, cellulose has the poorest flow per square inch.

Even hot, if there isn't enough surface area, or the media begins to plug up, at higher RPM with higher volume being moved by the pump, it's also possible for the bypass to crack open, allowing some oil to bypass the media.

With regards to the observations made, if the particulate is heavy enough to stay on the bottom of the crankcase and not end up going up the pick-up, it's never going to end up in the filter, you just flush it out with the oil change.
Ok, makes sense about the differential pressure. And the cold oil part. Could it be the filter was actually a bit clogged?

Thing is, the Harley is a dry sump system, so all the oil gets moved out of the crankcase, through the filter, through the galleys, falls back to the case, then scavenged to the tank and the process repeats. I pulled the scavenge drain plug and had some come out there as well, indicating to me, the oil had circulated. WE believe this came from an aluminum cam plate part change that was done earlier, and as of now, the oil has remained clean (non-glittery). What got me wondering was why I didn't see more on the filter itself, considering this stuff was basically floating in the oil.
 
Engine oil pressure and filter bypass pressure can't be compared.

The problem with the Harley and its metallic oil:
1. Engine a piece of junk, either assembled poorly at the factory or rebuilt horribly over and over somewhere else, or simply worn out.
2. Its modded excessively, which would require data to adjust oil grades, oil change intervals, filtering capability, oil cooling capability....
3. The oil chosen didn't match the engine well enough.
4. The interval chosen didn't match the driving style well enough
5. Filter media, where you can't see, is loading up too quickly. Filters trap within the media and not just on the outside.
6. Pathetic aftermarket box tune
7........... along with a million other possibilities

So, your concern with the filter has NOTHING TO DO with your metallic oil. Something else is going on.

Year/make/mileage/engine/mods/oil brand/grade/interval is a good start, along with some data like running oil pressure and temps..

If you can see the metallic shine in the oil, then you should consider a UOA to see what metals are coming up.

Punch the PN for info on that Wix filter. 5 micron nominal should yield a tolerable absolute micron rating with its synthetic media. This isn't your normal Wix car filter.
I'm not asking what the cause of the metallic particulates are, I am asking why the filter didn't seem to catch all of it. So yes, this does concern the filter. Either its not getting filtered, its already clogged beyond its design parameter's, or another issue. See my above post.
 
I'm not asking what the cause of the metallic particulates are, I am asking why the filter didn't seem to catch all of it. So yes, this does concern the filter. Either its not getting filtered, its already clogged beyond its design parameter's, or another issue. See my above post.
Really fine metal particles will still make their way through the filter and bigger particles will likely sink in the sump or get held up against the pickup screen and never make it into the filter.
 
Ok, makes sense about the differential pressure. And the cold oil part. Could it be the filter was actually a bit clogged?

Thing is, the Harley is a dry sump system, so all the oil gets moved out of the crankcase, through the filter, through the galleys, falls back to the case, then scavenged to the tank and the process repeats. I pulled the scavenge drain plug and had some come out there as well, indicating to me, the oil had circulated. WE believe this came from an aluminum cam plate part change that was done earlier, and as of now, the oil has remained clean (non-glittery). What got me wondering was why I didn't see more on the filter itself, considering this stuff was basically floating in the oil.
Yes, if you are shedding a lot of material and the media plugged up, absolutely. I also agree with @Greasymechtech that this is a decent synthetic media filter, I think it's around 95% at 20 microns based on a previous thread on it on here. Synthetic media filters have higher holding capacity, but there's still a limit.

Did you run a magnet through the oil to see if the particles were ferrous?
 
Yes, if you are shedding a lot of material and the media plugged up, absolutely. I also agree with @Greasymechtech that this is a decent synthetic media filter, I think it's around 95% at 20 microns based on a previous thread on it on here. Synthetic media filters have higher holding capacity, but there's still a limit.

Did you run a magnet through the oil to see if the particles were ferrous?
Yes, none stuck to my magnet, so assuming they are aluminum, since that is a majority of the cam plate and oil pump (sans the oil pump gears, of course)
 
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