Exactly how does a carburetor oil bath filter work?

[central52]

Took the old oil bath carberator filter off, cleaned it, painted. Looks nice. But, I'm curious as to how the thing works. As I see it, the oil fumes rise up to the top horsehair mesh? Ed

[Ulu]

The air reverses direction quickly, as the engine sucks the air through. Inertia of the dust causes it to just keep going straight, and it's captured in the oil as it's "flung" free.

[Don Coatney]

Did you try Google?

 

 

 

 

 

[Ulu]

You should see the mud that collects in the bottom of a big industrial oil bath air cleaner. And it got hard too. Sometimes I had to chisel it out. I think the oil made it turn to adobe or something. LOL

[Plymouthy Adams]

You should see the mud that collects in the bottom of a big industrial oil bath air cleaner. And it got hard too. Sometimes I had to chisel it out. I think the oil made it turn to adobe or something. LOL

er that is oil-tite or maybe oildobe

[BobT-47P15]

The funny thing (or neat thing) is that these air cleaners are pretty efficient........even if kinda messy with the oil.

Many people have converted them to use a paper air filter, but that's not really necessary.  Unless you want to

go to a completely different style filter.

[central52]

great information, guys. thanks. My manual says to use 50 weight oil. In cold weather, would a lighter weight oil be better? All those Dodge trucks in WW2 must have used this oil bath system, so it must be pretty good. Ed

[doctor dirt]

Lived in Hamden for a while originally from New Haven, I miss the apizza palors, Sally's and Pepe's would

have to be open 24/7 down here the pizza stinks.

 

Theres a level mark inside the bath and I was using marvel mystery oil because I had an old can.

Good luck riding and get a slice for me. I miss those great restraunts up there.

Doc.

[Don Coatney]

It is my opinion that most any oil should work. Nothing is getting lubricated with the oil in the air cleaner it is simply filtering the air. Even used engine oil should work. But as I said that is my opinion. Use what makes you feel good and what you are comfortable with.

[Eneto-55]

I don't know about tractors here in the States, but I had a Yanmar Micro-tractor in Brazil that I bought in 89, and it used an oil bath filter.  I tend to think that they work better than a paper filter, even with the oiled foam sleeve.

[Ulu]

I'm with Don on this one: almost any oil will work and the same oil as the engine uses is normally used for simplicity.

 

These things work GREAT, and if they didn't you would NOT see them on every big truck and industrial engine out there. In addition to what I mentioned, there is an oil-vapor drenched oakum or steel mesh filter that "scatters" the air plus there is a vortex action of the moving air that "centerfuges"  the dirt out of it.

 

They became unpopular on passenger cars because someone really has to clean them. You wash the entire thing in kerosene or diesel oil to clean it, then blow it out & dry it. It takes about 5x as long as changing a paper filter & it's messy too. So the labor was a big factor.

 

The other factor is sorta styling related. Over time hood lines got lower and lower and the oil-bath wouldn't fit under the hood anymore. On a truck they just clamp it outside the cab or fender or cowl. Who cares how it looks if the engine lasts 500,000 miles? On a car you must hide it.

[greg g]

The death knell for the oil bath in cars was the yearly lowering of the hood line by designers going for longer lower wider look from the mid 50's toward. Still used in heavy duty severe dust environment equipment.

[central52]

OK, Oil bath filter seems the best way to go. And, yes, Sally's., Pepe's, and others, like Modern Appizza, are great. Ed

[ghowie12]

I would like to offer some alternative views on this subject.  The oil bath works as described above but its effectiveness depends upon air velocity.  At idle it does virtually nothing because the air velocity is too low to fling the dirt out.  Second oil viscosity is important, the oil must be thick enough to not be easily sucked out by the velocity of air going by.  It is not uncommon to find that at WOT/RPMs in 2nd gear to suck the oil out of the oil bath aircleaner.  Third maintaining the exact oil level is extremely important in maintaining its effectiveness.  If the oil level drops the cross sectional area for air flow increases so the air velocity goes down and the effectiveness of the air cleaner goes down.  

 

The only two good things about an oil bath air cleaner are 1-they are user serviced and cost virtually nothing to do so and 2-As they fill with dirt they do not restrict the airflow and richen the fuel air mixture by somewhat choking the engine

 

IMHO opinion several changes over time have improved the life of engines, 1-more paved roads and less dusty gravel roads, 2-THe paper air cleaner element that is effective at all engine speeds, 3-Improved metallurgy in the engine 4-more powerful engines,more transmission gears and higher overall gearing resulting in fewer revolutions per mile and 5-Improved oil technology.

[T120]

I don't agree that oil bath air cleaners are inefficient nor have I experienced oil being sucked out of the reservoir at high RPM. However, neither am I racing at Bonneville with an oil bath air cleaner...

[Ulu]

 . . .nor have I experienced oil being sucked out of the reservoir at high RPM...

 

I have, and have had wind blast suck oil from them too. The one on my Scout has a small blast shield for that.

 

The industrial ones work very well, and are rather tall so they develop some velocity even at idle. Also they're designed so gravity helps pull the dirt down.

 

On those engines, most of the running hours are at working RPM. You don't idle industrial/commercial engines unnecessarily.

[T120]

I have, and have had wind blast suck oil from them too. The one on my Scout has a small blast shield for that.

 

The industrial ones work very well, and are rather tall so they develop some velocity even at idle. Also they're designed so gravity helps pull the dirt down.

 

On those engines, most of the running hours are at working RPM. You don't idle industrial/commercial engines unnecessarily.

 

Interesting... As far as high RPM on the older vehicles, I'm thinking not much above 3000 RPM - It can get windy here in southern Alberta as well. Newest vehicle I have with an oil bath air cleaner is my 1977 Ford F250.I haven't experienced that problem on any vehicle I have to date. If a vehicle came equipped stock with an oil bath air cleaner I don't see any point in changing to a paper filter unless modifying the engine for performance reasons and changing carburetion or maybe personal preference,but that's an individual choice. 

Edited May 7, 2015 by Ralph D25cpe

[Don Coatney]

Only way I know of to have an oil bath air cleaner suck oil is to over fill it.

[Ulu]

Drive a Scout over a washboard road a bit too fast...

[Don Coatney]

Hit a tree at 30MPH and your radiator will burst. Push anything beyond it's limit and it will fail.

[Ulu]

HehHeh...yeah...that'd do it.   

 

I used to service lots of heavy equipment for a rental company. You should see what gets in the oil bath when someone drives a 12 ton Wisconsin road roller into a canal.

 

(Not me. I had to help winch the damn thing out. Took 4 trucks to do it.)

 

Only time I ever saw a trout come out of the air filter.

[Merle Coggins]

You should see what happens to an oil bath air filter when the engine gets snuffed out and it kicks back and begins to run backwards. I saw that happen to an old Cat diesel in an American crane. They had one hell of a time getting it shut down, and by the time they did it had blown all of the oil out of the filter and all over inside the engine compartment. What a mess.

 

Merle