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Oiling the Foam Air Filter

Posted by optsyeagle (My Page) on
Mon, Sep 22, 08 at 19:22

I have a Yardworks 4.75Hp walk behind mower with a Tecumseh motor. It has one of those green foam air filters (rectangular with a knife cut about 1 inch in, to allow it to fit into the black housing).

My question is: Am I supposed to soak this with motor oil and if so, would simple 10w30 work for this?


Follow-Up Postings:

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RE: Oiling the Foam Air Filter

After cleaning the foam in a degreaser, then dry it by squeezing in a dry cloth or paper towels. then add 1 teaspoon of oil 10-30 oil is fine then squeeze the foam to spread the oil and you are done.


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RE: Oiling the Foam Air Filter

Just like above- but be cautious on the type of de-greaser. It is better to use dish soap and water if that is all you have-then rinse well, rather than use a solvent that can damage the filter.


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RE: Oiling the Foam Air Filter

Also, you can use a special air filter oil in a spray can - it's 'tackier' than regular oil and will catch more particles.


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RE: Oiling the Foam Air Filter

Do you guys do this at the end of the season with the regular maintenance or at the beginning of the new one?


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RE: Oiling the Foam Air Filter

saxman, where do you get that special air filter oil?


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RE: Oiling the Foam Air Filter

I wouldn't use degreaser. Too much solvent left behind and not enough volume of liquid to carry away debris. I suppose a degreaser would be ok in a two step operation with the 2nd step being a good washing in Dawn dish liquid and hot water. Remember there are abrasives caught in that filter just trying to get into your engine. Wash the filter like there's no tomorrow. Dry it with paper towels or a cotton rag. Re-oil the filter with motor oil. A teaspoon is not enough in my opinion. Put enough to really soak the thing then squeeze the excess out by squeezing it thoroughly in a clean cloth or a bunch of paper towels. I don't like Saxman's (sorry Sax it's just my opinion) idea of using (K&N type) spray filter oil unless you use a whole bunch and really work it in. A surface treatment is not enough. Be careful when changing the filter not to let debris get into the intake area during the process.


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RE: Oiling the Foam Air Filter

I was specifically not referring to K&N filter oil, which is non-tacky. Filter spray can be found most anyplace, maybe even Wal Mart. As with any filter oil, you have to work it in, not just 'spray and pray'. Actually, my personal favorite that I used for years when I had 2-cycle mowers is 'CorrosionX HD'. This stuff is very heavy-bodied and almost glue-like. On my old B&S mowers of yesteryear, I just used engine oil on the filter like everybody else. I would use the other stuff now, and I will when I service the pre-filter on my LB 22271 for the first time.


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RE: Oiling the Foam Air Filter

If you have any bar and chain oil around the garage use that instead of 10w30 or whatever. Bar and chain oil is thicker and tackier than other oil and won't settle to the bottom of the filter like 10w30.

Neal


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RE: Oiling the Foam Air Filter

Some engine manufactures no longer recommend oiling the pre-filter. Some come right out and say "Do Not Oil the Pre-Filter" in bold type. I think the reasoning is that some of the oil gets on the paper element and restricts the air flow. I had this happen on my Kawasaki 18hp AC twin engine. The paper element looked clean because the prefilter was picking up most of the dust (When it was oiled). Even though my paper filter looked really clean, it restricted the air enough to cause the engine to run rich, causing black soot to appear on the front wheel near the engine exhause. The spark plugs were also turning black. Replacing the paper filter fixed the problem. I asked my JD dealer if I should oil the pre-filter, and he said "Absolutely Not" Charles Ranheim


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RE: Oiling the Foam Air Filter

Over oiling the pre-filter will cause problems as you indicated but not oiling it at all is just as bad. Oiling it correctly is the way to go and it will function nicely. If you have any oil on any foam filter that settles to the bottom in any quantity then you're over oiling it. A properly oiled foam filter has very little oil left in it. I use a dry clean cotton rag to absorb as much as possible. If you do this there will be no problem with pre filter oil getting on the paper filter. A foam pre-filter that isn't oiled serves no function at all in my opinion.


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RE: Oiling the Foam Air Filter

The pre-filter on my new Honda GSV190 engine came oiled from the factory and the manual backs that up, so it will be oiled. If there's enough oil on a pre-filter to migrate to the paper filter, it was simply over-oiled or the wrong oil was used. You have to use common sense if you don't have mechanical intuition. The purpose of the oil is simply to make the filter sticky so it catches and holds the smaller particles that otherwise might get through. The filter doesn't need to be dripping. After oiling mine, I will squeeze it out in some paper towels until practically dry. There's still plenty of oil on it, but not enough to migrate to the pleated filter.


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RE: Oiling the Foam Air Filter

When I used to oil the pre-filter, I used SAE 20 oil, squeezed it together to distribute it evenly, then squeezed it with paper towels until I could not see any more oil coming out of the filter. Apparently, this was not enough. It still contaminated my paper filter enough so that it restricted the flow of air, even though it looked clean and dry. In a previous thread, someone suggested applying some 50:1 gas/oil mix to the pre-filter. I did not try this, but it would certainly reduce the amount of oil left on the pre-filter. By the way, when I stopped oiling the pre-filter, it not only eliminated the black soot that used to appear on my front tire, I burn less gas to cut the same lawn. I have to agree a small amount of oil on the pre-filter will help trap some particles reaching the paper filter. Right or wrong, this is just my observation. Charles Ranheim


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RE: Oiling the Foam Air Filter

I wash out my foam filters in dishwashing soap and warm water and let them dry in the sun for a few hours. Then I drop them in a ziplock bag with a squirt of bar and chain oil, seal it up and knead the filter through the bag to distribute the oil evenly. Unzip the bag and pat dry then install, keeps you cleaner this way and the bag is reuseable.


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