Judging air filter restriction

[doitmyself]

I know about air restriction gauges, but are they "calibrated" for different engine needs?

I also know that modern engines adjust to clogged filters, so restriction is not as critical as carburated engines.

In the old days, carburated air filters got really dirty and grimy, indicating change.

I am proposing that today's used filters might be dirtier than the eye beholds.....but I don't know if this is relevant per above.

Here are recent pictures of my caravan filter at 20,000 miles next to a new one, and it looks relatively clean. But, look how little light gets through the used filter vs. new. Does this mean anything? Please, no flames for this crude example.

And, how do I get my pictures bigger from photobucket!!!!

 

[ARCOgraphite]

If you could afford it, 1x per year install a new filter after "Spring street sweeping" season - this has been my plan since without a test flow bench you would have a hard time knowing when to change.

 

[daman]

Originally Posted By: doitmyself
But, look how little light gets through the used filter vs. new. Does this mean anything?

Yea it means it's full of dirt..

 

[Dave Hess]

I just change it every 30K miles

 

[hisilver]

Looking at the old one next to the new, it looks pretty darn dirty anyway without the flashlight test. I would change it.

 

[The_Jeff]

If you were to retrofit one of those restriction things (like a "turkey popper" I would find one from a still, low airflow design and install it in a similar still, low airflow section of the intake tube. Don't want the venturi effect skewing results.

Remember, they catch more stuff after the big holes fill up, so too new too often has its downside.

 

[doitmyself]

Originally Posted By: eljefino
If you were to retrofit one of those restriction things (like a "turkey popper" I would find one from a still, low airflow design and install it in a similar still, low airflow section of the intake tube. Don't want the venturi effect skewing results.

Remember, they catch more stuff after the big holes fill up, so too new too often has its downside.


Yes, I am trying to change my ways. I just found Widman's poorly named restriction gauge thread....an eye opener.

Elj...I am equally curious about my workplace tractor filters. After 3 years, they too looked plugged by the flashlight test, but the restriction gauges haven't budged. I need to judge the time interval where I think that maybe the filter paper or rubber degradation might be the determining factor.

At least someone here should give me a hug for not following the JD tractor manual's recommendation for annual replacement.

Anyone? Boraticus, maybe?

 

[Jim Allen]

Manly electronic hug given!

My Farmall has an electronic indicator, but it only shows red yellow or green. It's neve budged. I will soon replace it with a Donaldson "Informer" to see what it's actually doing. I replace the air filter just once, right after I bought it five years and a few hundred hours ago. I look at it every year at service time but haven't done anything but dust it off.

 

[shrooms]

"And, how do I get my pictures bigger from photobucket!!!!"

Make sure the pic is at least 600 x 800 pixels or bigger.

 

[Newtonville]

I don't believe the used filter is better theory. The big holes don't get filled first, the little ones do. The dirt causes more restriction and more suction on the element, pulling through more dirt than before.

 

[widman]

I've just gone through an evaluation for someone who rebuilt his Komatsu WA180 Loader last year. It is being overhauled again this year with less than 2000 hours on the rebuild by the Komatsu shop. Bottom line is the operators were not waiting for the restriction gauge to show restriction. They has set up a procedure to take out the filters before every shift and "inspect" or "clean" them. I kept telling them that 221 ppm of iron and 93 ppm of lead was not normal.
Owner is very upset. Lets see if they listen this year.

In a class I gave last week to 25 mechanics at one of the oil companies I showed this filter. Every mechanic said the filter was still good. It was actually drawing 25" of restriction and pulling dust around its seals.

 

[Jim Allen]

To be sure I understand this correctly, Widman, your conclusion on the Komatsu is that by constantly removing and "checking" the filter, they caused more trouble than if they had just left in place and followed the filter restriction gauge? If so, I would agree, because you can be sure that if a filter is removed every day for inspection, you can bet that at least one bozo isn't going to get it in right at some point. Plus, who knows how they "cleaned" it. And, removing a filter on a dirty jobsite is probably not ideal either.

 

[Samilcar]

Originally Posted By: Newtonville
I don't believe the used filter is better theory. The big holes don't get filled first, the little ones do. The dirt causes more restriction and more suction on the element, pulling through more dirt than before.


http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.122.3342&rep=rep1&type=pdf

This is a paper on Ford's 150,000 mile air filter that they use in the new Focus. A lot of information here, but there's a graph on page six which illustrates the filtration performance benefits of not changing the air filter too early.

 

[widman]

They definitely over cleaned it and when I saw the filter (engine disassembled, but the filter housing was not disassembled), the safety filter did not have a wing nut (or any nut) on it.

The eye cannot measure restriction.

I have another demonstration going on with two Volvo F12 Trucks that work in the sugar cane fields (1200 liter engines) in real high dust. Visibility 10 ft.

Their maintenance plan called for daily cleaning of the filter. They insisted that the filters clogged in one day. I convinced them to put the restriction gauge on them with new filters with seals on the filter housings and call me when they show restriction. Test has been running for 2 months without showing restriction.

 

[Jim Allen]

Originally Posted By: widman
I have another demonstration going on with two Volvo F12 Trucks that work in the sugar cane fields (1200 liter engines) in real high dust. Visibility 10 ft.

Their maintenance plan called for daily cleaning of the filter. They insisted that the filters clogged in one day. I convinced them to put the restriction gauge on them with new filters with seals on the filter housings and call me when they show restriction. Test has been running for 2 months without showing restriction.


I like the way you think!

 

[Newtonville]

Originally Posted By: Samilcar
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.122.3342&rep=rep1&type=pdf

This is a paper on Ford's 150,000 mile air filter that they use in the new Focus. A lot of information here, but there's a graph on page six which illustrates the filtration performance benefits of not changing the air filter too early.

I stand corrected, as the article has some authority. Somehow, I am still not a complete believer though, not that it matters if I am or not. I still need an explanation as to why the small holes fill last and increased restriction increases efficiency, to be a believer. I still see opposing statements that new filters are better, by most engine makers, (my view also.) When I see filters running in dust and the restriction is just fine, it makes me ? and think the large holes are just passing more dirt, and the small holes are filled. Another thing is the initial quality of the air filter and uniformity. I use high efficiency air filters to begin with. Unfortunately all this takes a lot of time. Thanks for link, very good source of info.

 

[Scott_Tucker]

Why would you think the small 'holes' get filled first? Does only small hole sized particles get into the air filter? Dust is composed of many different sizes of particles. If the particle is too big it will not go through the hole but will get lodged into it. Plus the filter is not 2 dimensional. There are plenty of cavities as the particles pass through the filter media to stop it.

 

[Newtonville]

Small holes pass less percentage of the particles, whatever mix they are, hence get filled first. When they make layered higher capacity filters, like a Denso, the big holed layers go on the outside.