Oil bath air filter
- Thread starter KRB
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JC-jetro
Elite Member
air will enter the assembly thru the screened cap on top. Air has to travel thru the oil and peculate from the side of filter assembly to intake manifold. gravity will keep the oil in the cup so air suction by reciprocation of the piston can not introduce the oil in to the intake manifold. you need to take the oil cup out from the bottom and inspect closely to see the air flow pattern thru the oil. it becomes pretty clear. it is the same principle as "hooka" or "water pipe" with the filtering medium being oil in lieu of water.
JC,
Ford tractor
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What oil? Same as your engine oil. Just remember to change it to winter weight when the season gets cold.
Oil bath filtration is superior to dry element at having low restriction and getting out particulates. It's out of vogue due to the dramatically greater amount of maintenance needed. (and the mess)
Oil bath filtration is superior to dry element at having low restriction and getting out particulates. It's out of vogue due to the dramatically greater amount of maintenance needed. (and the mess)
oldyellr
Silver Member
Just to be clear, in a simple automotive oil bath air filter, as used in the 1950s, the air is not sucked through the oil. It enters the filter housing and is sucked downwards, then makes a 180ｰ turn around a circular baffle, just above the surface of the oil in the bottom of the housing. This causes dirt particles to be thrown out by centrifugal force and get trapped by the oil. For tractor use in very dusty conditions, more complicated oil bath filter can be used as shown here.
mostly_gas
Super Member
I use engine oil in my oil bath air cleaner, which is multi-viscosity. I do not change oil in the oil bath due to temperature.
RickB
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Well if you are using multi-vis oil in the crankcase, you aren't likely to be changing grades there, either. So the standard recommendation of using the same oil in the air cleaner as in the crankcase is still valid.
ModMech
Platinum Member
Oil bath filters are the BESt option for dusty conditions but are maintenance intensive, which is why they are no longer commonly used. I believe others have pointed this out as well.
They are WELL suited to off-road environments on mostly level ground, when you start talking about construction equipment that must operate on slopes, the advantage of the oil bath disappears quickly.
The oil sits in a bowl at the base of the filter assembly, air is dran into the TOP of the filter and flows downward towards the oil. The oil level covers the bottom of the "U" such that wit hthe engine off, there is no apparent way for air to get into the engine unless it actually goes thru the oil pool. In reality, during operation, a small smount of oil is pulled up into the internal passages of the filter assembly when allows the air to just barely sneak in above the oil level (which is a little lower with the engine running). The oil also coats a loose mesh inside the filter further enhancing dirt-trapping.
The air, once past the oil in the bowl, travels thru the oily mesh upwards to the lid or cap where it again takes a 180* turn into the intake (carb etc), but is very clean.
The harder the engine is working, the more airflow thru the filter, the greater the air velocity, the LESS likely dirt will make it past two 180* turns, the more oil is pulled upwards on the interior portion of the filter, the more oil on the mesh the better it is filtered.
Used oil is PERFECTLY ok to use in them, but as mentioned, it should match the crankcase viscosity as appropriate for the climate.
They are WELL suited to off-road environments on mostly level ground, when you start talking about construction equipment that must operate on slopes, the advantage of the oil bath disappears quickly.
The oil sits in a bowl at the base of the filter assembly, air is dran into the TOP of the filter and flows downward towards the oil. The oil level covers the bottom of the "U" such that wit hthe engine off, there is no apparent way for air to get into the engine unless it actually goes thru the oil pool. In reality, during operation, a small smount of oil is pulled up into the internal passages of the filter assembly when allows the air to just barely sneak in above the oil level (which is a little lower with the engine running). The oil also coats a loose mesh inside the filter further enhancing dirt-trapping.
The air, once past the oil in the bowl, travels thru the oily mesh upwards to the lid or cap where it again takes a 180* turn into the intake (carb etc), but is very clean.
The harder the engine is working, the more airflow thru the filter, the greater the air velocity, the LESS likely dirt will make it past two 180* turns, the more oil is pulled upwards on the interior portion of the filter, the more oil on the mesh the better it is filtered.
Used oil is PERFECTLY ok to use in them, but as mentioned, it should match the crankcase viscosity as appropriate for the climate.
mostly_gas
Super Member
Rick, Ford_Tractor was talking about changing oil bath for cold/winter operation and I was explaining why I don't change it.
Bird
Epic Contributor
Yep:laughing:, I've cleaned and changed the oil in a lot of them when I was a teenager in Dad's service stations, but I can't recall even seeing one since the 1950s.
