To Oil or Not To Oil My Foam Prefilter???

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I have a Honda 20 hp 2 cylinder engine. It has a paper element and a black foam element that is the prefilter. Am I supposed to just wash off the black foam filter to get the junk off/out of it and then reinstall? Or am I to wash, dry and then apply a small amount of oil? IF I am supposed to oil it, does it matter about the oil?
 
I had a JD lawn tractor that used a foam pre-filter. Every fall I would wash it with Dawn, then give it a small dime size dab of Marvel Mystery Oil. I worked the MMO in until it was all even in the foam. I cleaned it again one more time and then when I put it away for winter. Never had a problem.
 
A non-detergent 30W mineral oil is best for this, as it will not attack the foam.

Use the oil VERY sparingly - its supposed to be a light film on the pores - NONE of the pores should be filled with oil anywhere!

Massage it until all oil is spread very evenly.
 
The reason I asked this question was years ago my paper element looked clean but was actually clogged. We are assuming it was from my over oiling. It was suggested that I shouldn't apply oil to a foam prefilter as it may end up releasing some of the oil into the paper element thereby clogging it up. That is the point of my question. From what y'all are saying, it appears we are to apply oil but very, very sparingly. Is this correct?
 
Usually a Pre-Filter is used to capture large particles.... so I would say it probably doesn't require oil.
 
I think I would clean it of all debris, wash it in gentle soap and let dry and then reinstall without oil since you have another filter behind it

It is probably there to collect big grass particles, etc
 
With paper filters the foam element isn't supposed to be oiled. Blow both elements out with compressed air, put them back in and go to work.
 
I've never gotten into blowing out filters with compressed air. Do you blow the dirty side or from the clean side through the filter? If the former, you'll get the large bits out, but likely push fine particulates further into the media. You could also damage the media.

I've always simply vacuumed out filters like this. You'll get most of the junk out a little more gently.
 
Originally Posted By: gathermewool
I've never gotten into blowing out filters with compressed air. Do you blow the dirty side or from the clean side through the filter? If the former, you'll get the large bits out, but likely push fine particulates further into the media. You could also damage the media.

I've always simply vacuumed out filters like this. You'll get most of the junk out a little more gently.


Blow from the clean side to blow the dirt collected on the opposite side off. Been doing it for years. Just don't use 200 lbs. of air pressure. Forty to fifty lbs. is enough to get the job done without damaging the element.
 
Originally Posted By: boraticus
Originally Posted By: gathermewool
I've never gotten into blowing out filters with compressed air. Do you blow the dirty side or from the clean side through the filter? If the former, you'll get the large bits out, but likely push fine particulates further into the media. You could also damage the media.

I've always simply vacuumed out filters like this. You'll get most of the junk out a little more gently.


Blow from the clean side to blow the dirt collected on the opposite side off. Been doing it for years. Just don't use 200 lbs. of air pressure. Forty to fifty lbs. is enough to get the job done without damaging the element.


Does a better job than vacuuming with a shop vac and slim accessory?
 
If the pre-filter sits on a mesh frame of some sort, oil it. If the pre-filter sits directly on the paper, do not oil it. The oil can soften the paper and ruin it, which you do not want.

My Kawasaki engine has the same filter setup with a foam pre-filter, sitting in front of a paper main filter. I oil the foam then squeeze out all the excess and re-install. Works great, every time.
 
Originally Posted By: gathermewool
Originally Posted By: boraticus
Originally Posted By: gathermewool
I've never gotten into blowing out filters with compressed air. Do you blow the dirty side or from the clean side through the filter? If the former, you'll get the large bits out, but likely push fine particulates further into the media. You could also damage the media.

I've always simply vacuumed out filters like this. You'll get most of the junk out a little more gently.


Blow from the clean side to blow the dirt collected on the opposite side off. Been doing it for years. Just don't use 200 lbs. of air pressure. Forty to fifty lbs. is enough to get the job done without damaging the element.


Does a better job than vacuuming with a shop vac and slim accessory?



Beats me.

I've never used a shop vac to clean a paper air filter. Compressed air only. Been doing it for decades.

I doubt there would be much difference provided the shop vac has the power to pull air through the paper to dislodge finer particles.
 
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