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Oil bath air filter

could any of you old timers enlighten me as to the ins and outs of an oil bath air filter? kubota tractor diesel the tractor will only run when i remove the oil bath housing. once reinstalled it seems to just choke itself and not start. plenty of blue smoke, but no combustion? thoughts?

An oil bath filter is what a K&N filter is. It has a inefficiant media where oil must be added to trap dust particles until the filter is seasoned. The filter is probably so caked with dust that air can’t get through to the engine. So either the filter must be cleaned and reoiled if possible, or replaced.


K&N is not an oil bath filter. I had an oil bath filter on my 57 Olds, replaced it with a later model paper filter.

Unfortunately, I don’t remember much about it other than it had a ring shaped trough that you put oil in. Somehow the air is drawn through the oil to trap the dirt. You changed the oil in it periodically.

I’m guessing though that the OP has overfilled the oil bath air cleaner.

I agree with Keith. The K&N is an oiled media filter. I have seen an oil bath filter for a very long time, at least not one in a car. They would be a poor choice for a modern car.

As for the OP’s question, Clean the filter out with a solvent. Often kerosene was used, then re-oil it as instructed, If I remember correctly all the one’s I worked with specified 30W oil.

You’re correct. A K&N filter is an OIL-WETTED filter. An oil bath filter does have an oil trough where oil gets pulled into the filter media for better efficiancy in filtration. So either it’s overfilled with oil, or the filter’s dirty.


Could the air filter have too much oil? Would it do this if it had been over-oiled?

Edit: Damn, you guys are too fast for me.

OK… i asked the wrong question.

stump me…

i looked up into it, and lo and behold there is a paper element up inside the housing. clogged to #$%^. time for a new cartridge filter.

this is not like a K&N. the filter is supposed to be dry, no oil. the oil bath is like a prefilter to strain the bug stuff out. i just didn’t look far enough until i found the filter cartidge.

I’m not familiar with the Kubota setup but my antique Harleys all use the original oil bath air cleaners (2 separate styles).
One is a copper mesh that is soaked in oil and the excess is allowed to drain. If not, this can choke them down.
The other type uses 2 paper cartridges with an oil resevoir in the bottom of the air cleaner housing. This is the WWII military style cleaner and overfilling the oil resevoir can also choke it down.

Likewise if the paper cartridges on the military style are dirt saturated so I tend to go along with Tester here.
If the tractor has paper elements it’s possible they’re clogged by particles and it simply may not appear that way to the naked eye.

I recommend Consulting The Kubota’s Owner’s Manual For Maintenance Requirements.

You could also be overlooking other items of importance.

That’s how we “old timers” have always done it.

By the way, you just reminded me of the oil bath air filters on my former “old Beetles”. I don’t miss those.

The oil bath filters were very effective and simple to service. The first engine I overhauled was a Briggs $ Straton which had an oil bath filter with a glass bowl.

and i quote:

“the air filter very important to correct operation of your tractor. keep clean, and ensure oil to full mark.”

not very helpful.

but, since this tractor is over 30 years old, there is a gap in useful info to be found. now in the light of day, with a mirror and sun, the inside of the filter is made up of wire mesh, with a corrugated/perforated frame. seems all welded together. what i thought was a paper element was just a fine patina of grit all over the inside of the housing. (makes me think bad things about the air intake.)

well as far as other items: the other items are fuel, it is getting that, glow plugs, the light comes on, and the other is air. but the air seems to be confirmed by the removal and re installation of the oil bath changes the way it performs. (it dies)

you mention the beetle air filters. how did you clean those? did you have to clean the wire screen part too? or was it just the oil cup and bowl assembly?

i just can’t fathom why the whole air cleaner would have to be disassembled and removed from the tractor to be cleaned? unless i am missing something about general oil bath filter construction and use.