Blowing out a filter does not work.

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Chris142

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I put a air filter restriction gauge on my truck. It got pulled down a bit so I tried blowing the filter out. I spent a few minutes carefully blowing the dirt out from the clean side. When I was satisfied that I had it all out I inspected the filter for any damage I may have caused.

Didn't see any damage so I put it back in and reset the restriction gauge. Drove to work the next morning and then looked at the restriction gauge. It was sucked down again!

All I can figure is that the dirt gets stuck in the paper and cant be removed by blowing it out from the clean side.
 
Might be some oily residue in the pleats that really hangs on to debris. I typically shop-vac them off, but not so much with engine air filters. Mostly cabin air filters. Engine air filters I just replace.
 
Last edited:
Originally Posted By: JTK
Might be some oily residue in the pleats that really hangs on to debris. I typically shop-vac them off, but not so much with engine air filters. Mostly cabin air filters. Engine air filters I just replace.
Ya I was trying to be cheap. My air filter is a little expensive but no luck.
 
I also tend to blow out / vacuum air filters but mostly mid cycle just to get some leaves, dirt, etc off to continue use until it's time to change.

I'm surprised your gauge triggered so quickly. I figured you should have gotten SOME use out of the filter before it would trigger in... 2, 3, 4K miles or whatnot. Strange.
 
All I've ever done is hoover them, sucking on the outside. Doesn't work very well.

What I havn't tried is to hoover them in the filter housing, with the air intake taped to the hoover, sort of pneumatic back-flushing, though it'd be good if the reverse flow air into the filter was fairly clean.

http://www.widman.biz/English/Analysis/Cleaning.html

Some bad oil analysis results, claimed to be due to air filter cleaning (I assume with compressed air)

This is an interpretation of the results and, while it seems reasonable, doesn't seem to have been definitively proved.

It also seems to assume that filter-cleaning is inherently wrong. In other words, it makes no distinction between cleaning them "well" and cleaning them "badly".

These may be cases where dirt has been blown into the engine or the filter has been damaged. The consequences of this are likely to be worse in South America (or here in Southern Taiwan) than in the UK.

These people

http://www.airfilterblaster.com/

would disagree with you. They SELL a pneumatic back-flushing gadget, (As I suggested above. Like most of my nominally clever/fairly obvious ideas, it's already being done.)

This is aimed at construction/farming/mining plant which of course will clog filters a lot quicker/more expensively than most private cars.

The testing they detail isn't very scientific, pretty close to anecdotal evidence in fact, though that doesn't mean its wrong.

In particular, "damage" is operationally defined as "light doesn't shine through it". That'd be a good way of spotting actual holes, but I might want tighter criteria before I risked my shiny new bulldozer on it.
 
If you want to learn about on-vehicle filter cleaning, read-up on the Abrams tank. Multiple strategies used, most resulting from lessons learned from the Gulf War.
 
Originally Posted By: Rand
how much does it get sucked down with a clean filter?
none when new. It gets plugged pretty fast here through depending on the weather,wind and dust storms.
 
Blowing out a filter is a good way to kill your engine.
Here is Mann filters
https://blog.mann-hummel.com/wp-content/uploads/2014/Mythen/MF_10Mythen_EN_Ansicht_neu.pdf
And this is from CAT, they don't even want you to open the filter housing to insepct it let alone blow air or tap the filter to try to clean it. They say to go by the air filter restriction gauge, nothing else.
Page 24
https://caterpillar.scene7.com/is/content/Caterpillar/C10467200

Just because some one makes something they say is great for air filters doesn't make it great.
I can go to any heavy construction manufacturer and find the same thing on how NOT to clean them or even try to clean them.

Cris142
Don't know what "pulled down a bit" means. My S2000 pulls 0 restriction with the air box lid off but will pull 8"of H2o with the lid on, I just went 90k miles on my last air filter in that car. Doesn't your gauge give you a range of numbers like the Wix gauge? My Wix gauges start a 8 and go to 25" and I change my filters due to time(6 years) or when the restriction gets to 11" or 15" of restriction on my gas engines.
Here is the air box on a S2000, you can see my Restriction gauge on the right side of this pic


ROD
 
IMO, the decision on cleaning a filter should be done on a case by case basis. Many if not most of the PC filters are not nearly robust enough to get away with it... blowing... I mean, but it may be possible to gently hoover or use some other means. Some of my tractor filters are and are designed to be cleaned, so I do sometimes.

Overall WHY? If you don't have a restriction gauge, you have no basis of knowledge to do anything, so you shouldn't be touching it until the prescribed interval (which for most people is still WAY too early).

Chris142: Is that filter you cleaned a depth filter.. a synthetic lofted type. If so, that could be why id won't change after cleaning. As much of the material is buried inside as is on the exterior and the buried stuff is kinda stuck there. If you put in a new filter and the gauge doesn't trip, then there is your answer. If it does, obviously your gauge is suspect.
 
I'd check for a rodent nest in the air ducting. As mentioned, air filters can be ruined with compressed air.
 
Originally Posted By: Chris142
My gauge has a red and green area. Once the yellow gizmo gets pulled about 1/2 down power suffers and the truck really blows black smoke.

I would change the gauge out for one that gave you real numbers like the Wix gauge. If you still get a restriction then you have to find out what is causing the restriction. On my S2000 its the stock opening in the air box and I fixed it by cutting a 3" hole in the side of the air box and ran a 3" hose down to the fender well(no more restriction with the air box lid on). You might need a larger air filter or piping to the T/B. Some call it R/D or trial & error but its not to hard to make your intake less restrictive.

I get 50k+ miles on my stock air intake on my '13 Wrangler and thats with more than 500 miles of desert driving out of S. Calif, Yuma,AZ and southern Utah before the air filter needs to be changed. For yours to pull some restriction after so few miles is not right.

ROD
 
Last edited:
Originally Posted By: rrounds
Originally Posted By: Chris142
My gauge has a red and green area. Once the yellow gizmo gets pulled about 1/2 down power suffers and the truck really blows black smoke.

I would change the gauge out for one that gave you real numbers like the Wix gauge. If you still get a restriction then you have to find out what is causing the restriction. On my S2000 its the stock opening in the air box and I fixed it by cutting a 3" hole in the side of the air box and ran a 3" hose down to the fender well(no more restriction with the air box lid on). You might need a larger air filter or piping to the T/B. Some call it R/D or trial & error but its not to hard to make your intake less restrictive.

I get 50k+ miles on my stock air intake on my '13 Wrangler and thats with more than 500 miles of desert driving out of S. Calif, Yuma,AZ and southern Utah before the air filter needs to be changed. For yours to pull some restriction after so few miles is not right.

ROD
it was very dirty! I probly blew several ounces of dirt out of it. I can tell when its restricted by how the truck runs. Low power and lots of smoke when dirty.
 
Last edited:
Originally Posted By: rrounds
Chris142 said:
I get 50k+ miles on my stock air intake on my '13 Wrangler and thats with more than 500 miles of desert driving out of S. Calif, Yuma,AZ and southern Utah before the air filter needs to be changed. For yours to pull some restriction after so few miles is not right.

ROD


Diesels are not throttled, so a lot more air passes through them.

Anyway, this demonstrates that the pores of a filter (whether air or oil) are microscopic, and you're fooling yourselves if you think that you can tell whether or not a filter is plugged or not just by looking at it. You need some sort of delta P measurement, which is essentially what a restriction gauge is.
Click to expand...
 
Yes they are. I'm a retired owner operator and have a little over 2 million miles behind me. Now its just the wife, two dogs and me in a motorhome with no logs to fill out or pee test to take.
wink.gif


ROD
 
What about gently tapping the filter? That's what I did and got some dirt out, no grass was in it. The filter sits behind me about 12" above the engine.
 
Originally Posted By: motor_oil_madman
What about gently tapping the filter?


It won't affect the embedded dirt that increases restriction.
 
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