Originally Posted By: Ducked
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.
Anytime you think about the pulse cleaning or pressure cleaning of a filter and how certain applications work, you need to take into consideration the design of the filter. The filters designed for for pulse cleaning are
surface loading filters, where a fine mesh of nanofibers, 1 to 2 microns thick cover the surface, and the main portion of the media is mostly for support, but some depth of what gets through. The Dirt stays on the outside to be blown off (although eventually the depth pat will fill up. Automotive filters are
depth loading filters. You can't get that back out without some damage to the filter media.
My originally quoted procedure is an emergency procedure, as is says. It will get you back to civilization, but should be done carefully, and then replaced as soon as possible.
And
Quote:
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.
Not just an interpretation of results from a paper standpoint, but confirmed in field, admitted to by operators, witnessed personally.