What are the signs of an oil filter not filtering?

[TrevorS]

We've seen some recent cases of cut open filters that give members cause for concern.

The primary thing that would worry me is if oil is constantly bypassing the filter medium.

Is there any way to spot such a condition prior to cutting open the filter?

 

[Cristobal]

A very sudden change in oil color is one of the first signs.

 

[Warstud]

Fluctuation in oil pressure.

 

[dnewton3]

Yes - you can install a dP system such as what Jim Allen has done.

He has a very high-end monitor system that tracks input and output pressure across the filter (the vast majority of which is actually across the media, but technically would also include design and manufacturing of the entire filter oil path). The system even datalogs all the info several times a second. If you know Jim (an admitted gage-a-holic), you'd understand how credible and meticulous he is and how this system is about as robust that anyone could have short of being in a lab.

What I am to understand is that when cold, oil will only bypass the media only upon high revs. Once oil is warmed the bypass events are essentially non-existent, even with long OCIs.

Additionally, you cannot think of the bypass as a snap-spring event. Rather, it will crack open at some preset pressure (eg 8 psi), but not be fully open until some value after that (perhaps 11-12 psi?). The greater then dP, the more the valve will lift off the seat against the spring. And so, it's not as if ALL oil will bypass the filter media all at once. It is situationally dependent upon a great many things like oil temps, media loading, psi (typically in relation to rpm's), etc.

You will never be able to discern these bypass events with a typical dash oil pressure gage; they are not accurate enough and also only look at one side of the equation.

 

[Jim Allen]

You might not be able to tell in the course of a normal OCI. It would depend on how many contamination inputs there were. If the engine was a typical modern clean, run, low wearing, EFI engine, you might never know outside of a UOA.

BUT, as was said, a sooner-than-normal change of color (assuming you were paying that much attention) would likely be the first sign. And unless the media was completely blown out (which could be disastrous because it would push shredded media all thru the engine) SOME oil would still be filtered so it would be like being perpetually on bypass.

If the sending unit were upstream of the filter, you might see a drop of a few PSI but you'd have to have a very accurate gauge (most OE gauges are dampened so are not 2-4 psi accurate) and you'd have to have been paying enough attention to notice a needle's width drop on the gauge. My DP setup routinely shows 2-4 psi DP with warmed up oil and up to about 8 psi with cold (~45F) oil and the engine revved to 2500-3500 or more. Each engine/fitler combo would be slightly different but the point is that you'd need to have a very accurate gauge and have to know intimately how the OP gauge reads normally under all conditions and be paying special attention to see it.

 

[TrevorS]

Thanks Jim

I suspected color would be the main way to tell during use.

I do keep an eye on color and would say that my oil stayed slightly cleaner with a Pure 1 vs the current Motorcraft filter.

Of course with cartridge filters, I could just remove and inspect but I sense that cartridge filters are less likely to have a problem.

 

[bumperfood]

Use an infrared temperature gauge, aim it at your oil pan, then aim it at oil filter. The temperature in the filter should be as high if not higher then the oil in the pan. If its cooler then not much flow and getting plugged

 

[tig1]

Let the engine run for 2-3 minutes then feel if it's getting hot. If not the oil isn't flowing through it.

 

[TrevorS]

Nice ideas but the main concern I have is that the filter is broken internally so that oil is still flowing, just not through the filter medium.

 

[Bamaro]

You would probably never know.

 

[bumperfood]

If your filter has an anti drain component and it is no longer functioning, and is of large enough capacity, you might get an unfamiliar engine noise upon initial start up in the
am. Other then that, I don't see how you could know. If you are concerned, then you might want to install a two filter remote setup.

 

[ZeeOSix]

Originally Posted By: TrevorS
Nice ideas but the main concern I have is that the filter is broken internally so that oil is still flowing, just not through the filter medium.


If you had a delta-p setup across the filter, you might know based on what that particular filter runs for delta-p as a baseline. Then if one of the same filters had a noticeable delta-p shift from the baseline, you could maybe say something went wrong with it - like a media failure, etc.

Otherwise, you'll never know until you cut it open and look.