Pics of air filter change interval based on gage..

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Good afternoon BITOG,

Had the trusty 4Runner in the garage for an oil change. Last looked at the air filter back in the spring when I last serviced the truck. The filter was dirty then as it was a year ago when I installed a filter minder. Since I installed the filter minder a little over a year ago it's read 8" of restriction, I was tempted to change the filter a year ago but when the gauge still said it was ok I decided to see how much further I could go based off the gauge. Well at least a year is the answer, this filter is far far dirtier than I'd normally let an air filter get based on a visual inspection yet was still only yielding a restriction of 8". Basically it could've gone further. Silicon readings on the UOA have been steady for as long as this filter has been in service. I only elected to change it at this point to see if I could get lower silicon numbers with a fresh filter. My original intent was to run the filter to 11" of restriction then change, perhaps I'll do that next time. Outgoing filter was a Car Quest premium blue, new filter is a Napa Gold. Enjoy the pictures.






Filter was in service for 5 years and just shy of 40,000 miles.
 
My recollection of air particulate pollution (APC) d/p's was that 11" was very substantial. The baghouse filter differential pressures would typically run 4"-6" w.g. as they went through their cleaning cycles (2-3" was near new with max flow)....those were always taken at 90-100% rated induced draft fan rpm (or at boiler rated output...ie max heat flow). A number of 8" or higher seems headed to being "blinded."

I just checked my car's air filter at the 35,000 mi point and it didn't have any discoloration. Typically, I haven't run across dirty looking air filters the past 20 yrs. That 11 in. of diff press is certainly filtering much better, though at the possible expense of much less than full air flow into the engine. When I use to track idle to WOT vacuum on my old muscle cars it would range from 1-2" up to around 22" during full range of rpm. An 11 inch drop during normal running seems like a lot.
 
I like the K&N filter minder as it tops out at 10" which is IMO reasonable for a N/A gasoline engine. Thats only around 1/2 of a psi IIRC but at maximum flow it saw aka Wide open. Itd be like going up in elevation like 1000ft or so. You would probably only notice if you did a few passes on a drag strip with the old one and then a few with the clean one
Just driving around you won't see that kind of restriction since the restriction is normally the throttle blade.
 
My record is 105K on an air filter before it tripped a check engine light. It didn't look horrible, though maybe a bit dark. Sure enough, I couldn't see light through it when shined from the back.
 
Originally Posted By: Colt45ws
I like the K&N filter minder as it tops out at 10" which is IMO reasonable for a N/A gasoline engine. Thats only around 1/2 of a psi IIRC but at maximum flow it saw aka Wide open. Itd be like going up in elevation like 1000ft or so. You would probably only notice if you did a few passes on a drag strip with the old one and then a few with the clean one
Just driving around you won't see that kind of restriction since the restriction is normally the throttle blade.


I like that filter minder as well however they're really proud of them! I purchased 3 5-25/30" meters for less than the price of one 0-10" hence why I was planning to just change by 11". Seems like 8-11" is a reasonable time to change at least based on appearance. At least in this vehicle the AC or mechanical fan have more of an impact on performance than anything, I'm sure it'll run better with the new filter but I'm not sure I'll ever notice any difference.
 
Kestas: In what vehicle did you run an AF 105K?

In my world AFs look OK at 30K but are frequently sandy. Sand falls off them after removal. I just replace them.
 
Could somebody explain how a filter minder works and how it is installed? Thank You.
 
The best air filter document that I know of is “Nanofibers in Filtration Applications in Transportation” by Employees of Donaldson Company given in 2001. Here is a quote about consumers and light duty vehicles:

“Consumers must also make maint decisions about the air filters in their cars. This user group is relatively unsophisticated in their knowledge of filter maintenance and function. Air filters are perhaps the most easily serviced but least understood parts on a vehicle. Other common replacement parts on a vehicle such as tires, wiper blades, oil and oil filters work best when new. However, this is NOT the case with conventional air filters. Since most (dry) air filters rely on the formation of a dust cake to improve the performance of a filter media, over-servicing can lead to dire consequences from inadequate engine protection.

Over-servicing is common in light vehicles. Light vehicles are generally not equipped with filter restriction indicators. Air filters are often inspected by maintenance personnel during oil changes. In spite of the typical manufacturer's recommendation of at least a 30,000-mile change interval, it is common for dealers, service stations and quick lubes to recommend more frequent air filter changes. Given the frequency of oil changes and air filter changes at quick lubes, it is expected that many light vehicle filters are changed much more frequently than manufacturers recommend.

While this over-servicing phenomenon is frustrating to those who understand filter media performance, the filter industry has not sufficiently educated customers on how air filters function. Not surprisingly, filter manufacturers, distributors, dealers, service stations and quick lubes have economic incentives to change and sell more filters. It is also understandable that consumers believe that filters work best when they are new (like other parts) and have a clean appearance.

In spite of the best intentions of automotive mechanics and consumers, typical automotive air filters are notably inefficient at capturing particles less than 5 microns in size. Several studies have shown that particles between 1-5 microns cause engine wear, which will lead to increased engine emissions and shorter engine life. Because many car engine air filters are over-serviced, a typical automotive filter may operate most of its life without the protective benefits of a well developed protective dust cake. As the filter becomes dirty by visual appearance (and the dust cake finally starts working) the filter is often exchanged.”
 
Originally Posted By: pbm
Could somebody explain how a filter minder works and how it is installed? Thank You.

You drill a hole somewhere after the filter, often in the part of the filter housing that leads to the engine. Insert the provided grommet and the filter minder pushes in to the grommet.

Then you drive. I usually like to floor it at least once at let the engine wrap out once so it sees maximum air demand.
The Filter minder will 'ratchet' up and then show you how much restriction the air filter is causing in inches of water. As the filter gets more loaded it will ratchet up more and more until it reads that a change is due.
In his case, he has one that reads to 30" of water, which is too much for a N/A engine so he is stopping part way into its range. That size is suited more for a turbo charged diesel engine (The turbo makes up for the restriction by sucking harder, so there is no loss of power from the engine. Same way they dont lose but a few % going up into the high mountains.)
 
I had the K&n on my Mazda but a new filter would max it out. I put a filter minder and it’s been on 11” since pretty much new.
 
Originally Posted By: Kira
Kestas: In what vehicle did you run an AF 105K?

In my world AFs look OK at 30K but are frequently sandy. Sand falls off them after removal. I just replace them.

This was on a 2002 Volvo S40 with well-kept records. I know that even 30K can be too soon to change an air filter in mild environments, so I let it go as long as I dared. There was no down side to running an air filter too long, except for high end performance.

Back in the days of buying Hastings filters for $1 I didn't think twice about changing air filters at the prescribed interval or less. But with filters costing over $20, I like to get my money's worth out of them.
 
Originally Posted By: Colt45ws
Originally Posted By: pbm
Could somebody explain how a filter minder works and how it is installed? Thank You.

You drill a hole somewhere after the filter, often in the part of the filter housing that leads to the engine. Insert the provided grommet and the filter minder pushes in to the grommet.

Then you drive. I usually like to floor it at least once at let the engine wrap out once so it sees maximum air demand.
The Filter minder will 'ratchet' up and then show you how much restriction the air filter is causing in inches of water. As the filter gets more loaded it will ratchet up more and more until it reads that a change is due.
In his case, he has one that reads to 30" of water, which is too much for a N/A engine so he is stopping part way into its range. That size is suited more for a turbo charged diesel engine (The turbo makes up for the restriction by sucking harder, so there is no loss of power from the engine. Same way they dont lose but a few % going up into the high mountains.)



Thanks Colton: Are you saying that the hole should be drilled in the (smooth part) of the intake (as opposed to the accordion like section) downstream of the air filter housing?

PS: I ask because this intrigues me....I've always been a stickler for maintaining my vehicles but I'll admit that the A/F got little attention....I would change them out approx. every 30K (sometimes I would shake them out and reinstall every 10 or 15K but I stopped doing that because I was worried about proper sealing of the filter box after disturbing it...)
 
Originally Posted By: FlyNavyP3
... Silicon readings on the UOA have been steady for as long as this filter has been in service. I only elected to change it at this point to see if I could get lower silicon numbers with a fresh filter. ...
Not likely, because your old one was filtering small particles better than it did when new---as the Donaldson quote points out.
 
Wow, goes to show you can't really judge an air filter by visual inspection. The last fram air filter I bought recommended a change every 12k miles which is less than what most if not all car manufacturers recommend nowadays. Is this from ur first gen 4runner?

My 4th gen 4runner recommends the 30k air filter changes, so I'll go ahead and stick to that.
 
Originally Posted By: compratio10_5
....Because many car engine air filters are over-serviced, a typical automotive filter may operate most of its life without the protective benefits of a well developed protective dust cake. As the filter becomes dirty by visual appearance (and the dust cake finally starts working) the filter is often exchanged.”


Is pre-coating your automobile's new air filter to get it up to more optimum filtration levels quickly ever done...or even recommended? I know that is a must in the power industry with bag house filtration systems. One concern I'd have is any of the smallest pre-coat particles getting through the auto air filter on initial treatment. Never heard anyone suggest or recommend such a thing for car air filters.
 
Originally Posted By: 69GTX
... Is pre-coating your automobile's new air filter to get it up to more optimum filtration levels quickly ever done... One concern I'd have is any of the smallest pre-coat particles getting through the auto air filter ...
Maybe "pre-coat" a new filter by driving with it during the peak pollen season? If any of those particles do get through, they won't do as much damage as silicon-dioxide type dust.
 
Yes, Industrial dust collectors (baghouses) are often precoated with relatively course limestone powder but I have never heard of anyone doing it on a vehicle. Someone suggested visiting the dumpster at your local quick-lube but personally I just prefer to leave the filter in place until the filter minder gauge indicates significant restriction. One caution is to look over the filter, housing and ducting to be sure it is air tight. I have seen cracks in the bottom of the air tube corrugations and a mouse nest. Be sure that the filter is properly sealed and that the housing, ducting and fasteners are in good shape and then let the gauge do the pressure measurement. See the Filter Minder website for installation guidance.
 
I got 90k miles on my S2000 air filter and I changed it out do to time not restriction.
https://bobistheoilguy.com/forums/ubbthreads.php/ubb/showflat/Number/4224343/Searchpage/1/Main/260341/Words/90k+miles/Search/true/Re:_90k_Miles_on_my_S2000_Air_#Post4224343

ROD
 
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