The Stovebolt Site Forums The Shop Area Engine Shop Replace Oil Bath Air Cleaner?

I was told by an old timer that oil bath air cleaners are better than "standard" eliment filters. Is this true? Should I leave my oil bath cleaner on my 235?

www.digiflux.biz

Yes, and yes.

It's a matter of choice. Today's filters are far better than those made 50 years ago, and I would assume that they are just as good as the oil bath. One problem with the oil bath is that you can lose the oil. My 52 had one and I was either bouncing the oil out or sucking it down the carb somehow, there would be only minimal signs of oil on the carb exterior or surrounding engine components. And I was using SAE 30 oil. When I built a new engine I sold the oil bath and put on a modern filter.

.If you do happen to get the oil(which has trapped dirt in it)to slosh into the carb,your engine is ingesting the dirt that was trapped in the oil.
.It also takes more suction to pull air through the oil than a newer element type air filter.Sucking power and fuel mileage.

I appreciate all the advice. What I may do is add a paper filter over the oil bath. Is there a site that has any science on the subject?

It's my understanding that the air isn't pulled thru the oil. It is channeled downward towards the oil, then takes a sharp U-turn upward on it's way to the carb. Dirt can't make the U-turn and falls into the oil where it is trapped. Anyone who knows more about the physics of this, correct me if I'm wrong.

And the air is NOT contaminated with oil vapor droplets????

The vapor pressure of motor oil is extremely low so very little, if any, oil vapor droplets would be introduced. I would suspect that you would introduce more oil vapor into the engine (and still a very tiny amount) from residual oil on the cylinder walls than you would from incoming air passing over the oil surface in an oil bath filter.

My uneducated guess is that oil vaporization is negligble. These single-barrels don't pull a lot of CFM and the air path covers a lot of area until the last few inches where it is funneled into the carb. It also travels thru some mesh baffles on it's upward journey after passing over the oil. I would think that if oil vaporization was a problem, you would have to add oil to these things all the time and your neighbors would be after you with pitchforks and ropes for the blue fog coming out of your truck.

It is not the CFM.They all should pull 17 to 21in.Hg of vacuum.
.take your air cleaner off.Start your engine,put parking brake on with wheel chocks for safety.Get out by your running engine and rev it up to around 1500rpm.Put your flat of your hand over the top of the carb.After that,tell me that it will not suck vapors(containing particles of dirt).
.BTW,,,, how does your hand feel?

Luke,
I think what both Larry and I were trying to say was that regardless of how hard the carb is sucking, if there is virtually no vapor from the oil then there will be no oil vapor being sucked in. If you want to try an experiment, put some 30 wt oil in a glass bowl and set it outside and see how long it takes to evaporate. The more vapor a substance creates (higher vapor pressure) the faster it will evaporate.

Additionally, if the dust particle is so small that it is floating and being absorbed into microscopic oil droplets, then I doubt very seriously that it could cause any harm to your engine. Ash particles created by incomplete combustion of gasoline (and there is never complete combustion) would be many orders of magnitude larger than such dust particles.

With that said, I would never argue that an oil-bath air cleaner is more efficient at removing dust than a modern paper filter. I'm simply stating that minimal amounts of microscopic dust and oil are going to be the least of your engine woes, particularly with an old stovebolt .

As for the evaporation experiment, You need to take into consideration the effects of air flowing on or through oil.It does get warm near the engine.This thins the oil.
.Get a cup of warm oil and blow on it or use a straw to blow into it.Make sure no one is standing opposite of you very close.(remember that the vacuum of the engine has more force than you can blow.
.As for the element material in the oil-bath filter,oil does creep up into the fibers,not much but more than a paper or synthetic element.
.Oil-bath air cleaners are correct for the restoration however, I would leave it dry and install it on the truck for looks after I arrived at a show or meet.

Useful information (?):

http://www.ytmag.com/articles/artint6.htm

"In 1951, FRAM introduced the first dry-type carburetor air filter, replacing the previous oil-bath type filter. First used as original equipment on 1952 Studebaker models, this type of filter is used almost universally on today?s passenger cars." (from FRAM website)

http://www.roadkill.com/~davet/moto/air.filters.html

Mechaniac
If your theory on this is correct, then you have to feel sorry for all those poor saps that spent $70 or more for a K&N filter. All that they really have is a modern day oil bath. They just have to be cleaned and reoiled more often because there isn't a reservoir of oil at the bottom.
The new Hot Rod (June '02) has a very interesting article on air cleaner filters. They compared 4 so-called high performance $40-$70 filters against a $5.99 Purolator. On 250 rear wheel HP the Purolator only gave up 5hp to the best. In their attempt at measuring actual air flow they were only able to guess that it gave up about 10%. They admittedly didn't have the right eguipment for that and only approximated. Also, they made no attempt at repeating the test with dirty filters.

Hey Luke , cast your eye over the big truck industry , the more arduious the duty , the bigger the oilbath cleaner.
They must do that for reason .

The truth be known- Oil bath air filters "ARE" superior to corrugated paper filters on nearly all counts. To explain the scientific principles of how a oil bath filter works would mean explaining it in terms of "physics", which may not be necessary. In some of the more simple terms that many of the previous repliers have used I will try to explain what is happening. Yes, you do have dust, dirt and other particles coming in from the air into the filter. Most heavier particles will be trapped quickly by the abrupt turn of direction of air flow over the oil(vectors). The remaining particles will become attached to the oil vapor (similar to how rain is produced), the saturated oil-particle will then attach to the mesh screening. The heavily oil-saturated particle will then travel down the mesh screen to drop into the pan at the bottom and the heavy particle will sink to the bottom of the oil. If you use an oil bath filter under very dusty conditions you should clean it every 6,000 miles, cleaning the mesh screen and replacing the oil in the bowl, being sure to saturate the mesh screen so that it will have a "wicking" effect.

The use of oil bath air filtration is used in industrial use in Cement Industry, Steel Plants, Foundries and other related industries. They are a most ideal filter where surrounding air contains high dust concentrations.
So, keep and use your oil bath filter, you cannot get a better one designed for the job at hand. If you truly need a more indepth explanation feel free to email me with your questions.

I'm one of the "poor saps" LOL, that uses K&N air filter elements. The filters for a typical American round filter application cost around $40.In my opinion, in day , day out service, they are superior to any paper filter.They filter when wet and only need to be cleaned or reoiled once every few years.That 5 free HP increases rapidly as a paper filters restriction increases very quickly with age.Try one, you'll like it. last filter you will buy for your daily driver.

Most big trucks here use a replaceable element type filter,,,,,
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.
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Besides, the wick effect over a long drive lest the oil travel in the direction of the airflow>>>>>>into the engine!!!! :rolleyes:

The "wicking" effect spoken of- Is Downward- not up. The air flow is "through" the mesh- not up or down-.

Thanks for all the help and taking your time to respond to my post. I have decided to stick with the oil bath. One last question. What weight oil should I used in my 62, 3/4, 235 oil bath cleaner? 30w?

Why even use a filter, these engines run on DIRT don`t they???

How do you clean these things? I bought a second one at the swap meet in Arlington for $5. Now I need to know what solution to use to clean them. Thanks.

I believe the owners manual calls for 50W oil (except in coldest winter). 50W will, of course, keep down the alleged 'sloshing' and 'oil vapors'.

What I can't figure out, is if their use stopped because people found cleaning with kerosene or gasoline a bit too much trouble, or did Fram pay off the car makers so as to have a very profitable business selling paper for 100X what it costs to produce.

Or maybe, the oil filters just didn't fit anymore under the low slung hoods of the 60s....

Geez, people get out of shape over some simple subjects...... :rolleyes:

I found a tall Fram (CA 4282, I think) which fits the optional larger size air cleaner of my '48. I didn't want to hack up the mesh on the top so I used a cake pan from the kitchen. That adds a nice touch, I think. I'll polish it up real good if I can get to Heron in August.

K&N filters are known to not remove as small of particles as the paper elements they replace because they are too porous.

I have heard the old timers around here say that when Mt. Saint Helens erupted in '81 that the paper element cars got all choked up and siezed on ash but the oil bath cars kept going as long as you changed the oil in the filter every hundred miles or so.
Who cares if some oil gets sucked into the intake? It happens all the time in modern PCV cars and it also happens in two stroke engines. It doesn't really gum up the carb because it gets washed away by the fuel and it is pretty good for the valves and rings if it is a moderate amount (and it would have to be or your filter would run dry in short order). A piece of dirt suspended in an oil droplet doesn't do any harm to the cylinder. Just as many particles get through the fuel filter and into the engine. The oil bath air filter housing is designed so the air takes a convoluted path and any oil that comes out of the bath can't turn as fast as the air and smacks the wall and drains back into the reservoir anyway.

The oil never gets warm enough to get thin. There is a fairly high volume of fairly fresh air moving through it. The air under the hood while the car is moving hardly ever gets over 120 degrees and that isn't enough for the oil to get thin or outgas. It has to be in the 200-300 degree range.

I suspect that oil bath filters really got discontinued because they are more expensive to manufacture than a paper filter housing- you just have to stamp two halves of the paper housing and slap them together.

Josh, K&N claims their filters are superior to any paper filter in flow or filtering characteristics. Read this then decide who to believe. K&N facts

I was told that I could take apart my oil bath cleaner in order to clean it. It sat lopsided on the carb anyway so I was going to correct this at the same time as I feared that it was not drawing through the oil properly. Well after about fifty curses I decided that in fact it was not designed to be taken apart but take it apart I did. That wirey oil soaked element is really fragile and falling apart. I am going to chuck the guts of the cleaner and get a paper filter to fit inside the housing. If I want added protection I will just get a foam oil soaked slip on to go over the paper filter. I'm not fooling around with oil bath's any more.....Pain in the butt!

I know they claim that, (I have read it before) but it is only true until the filter starts to clog up with dust and then it leaks dirt like a seive. You need to clean and re-oil it every 10000 miles or less to keep it from leaking dirt, at least a paper filter has the property of clogging up and making you notice that it is going to need changing. I have firsthand experience using a K & N filter in a 1991 Ranger 3.0 engine in a fairly dusty agricultural region putting about 60,000 miles on it in 4 years. I ran it half the time with paper and half with the K&N, and if I didn't clean the filter every time I changed the oil I would notice dust start to build up in the intake pipe and throttle body that I would never get with the paper filter. I didn't get much performance increase out of it either. It just wasn't a bottleneck in my case.
If you are noticing that your K&N doesn't get dirty as fast as your paper filter did, that means that your paper filter is doing it's job and your K&N isn't.
K&N's are fine if you maintain them well, but a lot of people don't. Just because it doesn't look dirty doesn't mean it isn't. Sorry, I'm skeptical of what manufacturers websites leave out. As an engineer I know all about yelling loud about your product's good features and whispering or shutting up about the bad. Amsoil\'s filter
Filter efficiency compared using SAE J726C test procedure
The best way to get around flow restrictions is to make the filter bigger, not sacrifice flow for filtering ability.

Well, everyone selling a product claims theirs is the best ,that's for sure.And we all tend to favor this product or that .As a experienced tradesman,I use personal observations in the field to judge situations.This is a photo of the aircleaner housing on my 94 S10,using a K&N filter.I installed the filter element 60,000 miles ago when I bought the truck used about 5 years ago. The filter was cleaned once. As usual, the dam ditigal camera picture isn't the best. There is no dirt or crud on the housing inside the filter element.What you can see is a slight film of clean oil, probably from the crankcase breather.No dirt to be seen.The filter is dirty on the outside and clean inside.That throttle body has never been cleaned and you can see a lack of the usual dirt deposits on the plastic injector tops .I don't doubt your conclusions,the conditions you operated your truck in may have been more severe, but for me ,I have K&N's in 3 of my vehicles.
Happy throttle body

Maybe they have improved their design since I used it in the early '90's or their round filters work better than their panel ones. If it works for you, great. That's all that counts. I am just tired of hearing people say that K&N is the only way to go when it isn't.

I'm not sure I understand any of those methods of evaluating the value of a K&N filter.

The first thing that can't be debated is whether oil attracts dirt.
Anyone that doesn't believe that probably thinks they could walk a women through the center of a shopping mall without having to pry her out of every store in the place.

I believe that a properly oiled K&N could and should do a better job than a paper filter until it begins to get dirty. Oil attracts and collects dirt, and so the K&N will get dirty much faster than the paper. It doesn't have a choice, no matter what skeptics insist to the contrary. I don't doubt that the paper material is more restrictive when they are both clean. The Hot Rod article pretty much bares that out.

This is from that K&N web site.
If a filter is only being oiled once in 5 years and isn't getting dirty, then you must live in one hell of a clean dust-free area with never any wind or it just simply doesn't have enough oil on it. If you live in a agricultural area, it's clogging up right away and sucking dirt from around the sides like K&N says in the above quote.
My truck will stay with the oil bath and you'll never see me with a K&N on anything else.

Someone yesterday asked what to wash an oil bath filter in. I guess you could use several different solvents but my '47 shop manual says just to immerse it in part cleaning solvent and slosh it around. I also found that the fiber mesh quickly responded to that treatment by breaking apart in hundreds of small pieces. I got a really good suggestion from a fellow stovebolter to replace the mesh with several of those spiral wound metal pot scrubber do-dads that sometimes show up on the kitchen sink. I stuffed 6 of them in mine at a cost of about $5. Worked great for me although getting access to the guts of the filter took a bit of work to avoid ruining the housing. Good luck.

RanchTruck: Interesting idea for replacing the guts of the oil bath cleaner. This new material may be to porous and not hold the oil as well as the original material though.

I had to really screw around to take apart my 62 oil bath. I got so disgusted that I put aside
the oil bath guts and replaced it with a snug fitting tall paper filter. I need to make an extra
long screw to reach the wing nut but I think that I will be happier with the paper over the oil
bath. I am hoping to get a little more power too.

Does anybody make a foam "pull over" that you soak in oil to put around paper, auto filters? I know that they make them for lawn tractors.

OK Tab, I did a close inspection of two(2) oil bath aircleaners that I have. One is from a 55 1st 235 and the other is from an older 235. The 55 1st is shorter and had something that was akin to really kinky hair like stuff in it. The older one had a wire mesh in it. The 1st one is a total loss as far as the hair stuff goes and the piece that holds it in appears to be "spot soldered", so could be troublesome to render a repair. The second one only needs cleaning and it will work fine. The wire mesh in the 2nd one is fairly heavy so replacing the other stuff with the scrubbers seems like a good idea.
My question now is- Did Chevrolet make different sizes of the oil bath aircleaners for the same size engines, only make them in different years? I had thought they were all the same size.

Oly: My 62 has the "hair" element within. It was assembled by crimping the edges of the housing together. I decrimped with a big screwdriver working my way around like a can opener. When I got the top off (where the wing nut goes) and saw how fragile the "hair" was I knew that I didn't want to put it back together like this. I cleaned it and replaced the oil soaked hair filter with a nice tall snug fitting paper filter (STP, SA-3688). My only regret is that I dented the top of my cleaner trying to get it apart. Otherwise I am quite happy. What does your "hair" cleaner look like? I may be interested in it just for the top portion.

I like the way that - I have an oil bath air cleaner - rolls off the tongue. So, I will stay with that type. Besides they look cool. But to clean the element - what is the "Parts Cleaning Solvent" that is referred to in the Manual? Gasoline, Kerosine, or what?

And I have two of these filters just in case no one knows how to clean these things. I will tear one apart and put in a paper filter (if I can find one the right size). But that is my last resort. Again, I think they look and sound cool.

My 41 manual specifies gas or kerosene. Gas is a lot cheaper, but kerosene is easier to store and reuse.

I'd probably go with kerosene since it'll leave a film and prevent the oxidation (rusting) that would cause the mesh to fall to pieces. Plus, what are you going to do with the dirty gasoline?

Don't clean with gasoline. That's way too volatile and flammable.

Well, of course, if you smoke while cleaning with gas, that will take care of the dirty gas disposal problem. :p