The Stovebolt Site Forums The Shop Area Engine Shop Oil Bath air filter

I am running dual W-1 carters with paper air filters. It runs great and fuel milage is where it should be. Once i shut it off, fuel smell comes from the intake from excess fuel still in the runners and carb evaporation. I have two factory oil bath air filters I am thinking of using. My though is, the oil will act like a sewer trap and not let fuel vapor past it, thus not stinking up the garage when returning home. It may also prevent some fuel evaporation from setting.

The question I have is about mixture, will the air to fuel mixture change when changing to a oil bath, or from oil bath to paper filter?

Second question, stock engines use a 50 weight oil in the filter, running dual filters each will see half the air flow, will 50 weight be to heavy?

Any thoughts?

Joe

I'd like to add a small addition/correction to the above.

An oil bath air cleaner works by two methods:

First, the oil is used to entrap dirt, that is correct. But the cleaning action is 90% accomplished by the rapid change in direction the air must make as it get sucked 'down' then back 'up'.

HERE is a simple diagram

The last little bit of cleaning is done by the oil coated wire mesh.. this is simply hoping that the light dirt that didn't fall out of suspension collides with the sticky oil on the wire.

Thicker oil does nothing, and can actually have a detrimental affect (due to higher surface tension not allowing the dirt to adhere to the oil... but simply bounce off it.

Paper filters are not 'better' per se, just easier to maintain (no oil to mess with, no metal mesh to clean. Also, oil bath filter flow air much much better, paper filters are designed to clog up as the dirt fills the element.

I found a study which puts oil bath and paper elements into perspective in a test engine. What I don't agree with is that they ran the oil bath air filter with the improper amount of oil. They filled the oil bath air filter to only 50% of the fill level to 'accelerate the test'. What??? So if you never maintain your air filter it won't work... I agree with that. BUT they never used this 'accelerated wear' on the paper filter. So they, in effect, tested a new, high efficiency paper filter against an improperly maintained oil bath filter and determined that the improperly maintained oil bath air cleaner was not as efficient. DUH.

https://books.google.com/books?id=Q...%20oil%20bath%20air%20filter&f=false

A couple of years ago, I purchased two older original Edmunds oil bath air cleaners for my two Rochester carbs on my 37 261. I had been running cheap paper filters and thought the oil bath air cleaners would be more effective.
After running them a short time, I noticed my exhaust did not sound the same and I was finding an oil residue on my intake. I wasn't happy with how the exhaust sounded or about the thin layer of oil on my intake and surrounding parts so I decided to step up to the best filtering system available, two K & N filters. I have been running them for about a year and I am very pleased with the sound of the truck and the filtering system. The truth is, oil bath filters are kind of a pain in the right back pocket. Just my opinion.

Will they look better anyway! I guess I got some figuring to do on how to convert to dry element in oil bath housings. On the H.A.M.B. there is a post about this same thing, they all agreed the oil bath works good for what it is, but running dual filters slows the air down so much, dirt does't have the momentum it needs to fall out of the air steam. I always thought the air traveled through the oil and the mesh was to capture excess oil before entering the engine.

Joe

IMHO if the oil bath worked better the manufacturer's would still be using it. I put a dry element in the OB housing on my '38. It takes some investigating to find an element that will fit but it works. On my '38 the intake noise is higher with the dry filter. This explains how the oiled gauze and oil bath filters work.

I use spent Rotella T 15/20.

Weather or not any part on a vehicle works better than another carries no weight in the manufacturers decision to use it, it's which is cheaper.

The way they assemble them, you wouldn't think it was cheaper! I have the 216, '47-'53 filters. Seems to me they could have made a few changes so one could get it part for a better cleaning. I got my rusty one apart and see how a filter could be adapted, now it just getting the time do work on them.

Joe

In 49, the std air cleaner was just the mesh screen. The factory offered the oil bath for extremely dusty/dirty conditions.
The oil bath did a better job of filtering and was more expensive to make, makes sense that it was an option.

My 72 air cooled VW came stock w/an oil bath air cleaner. It also had extensive vacuum and mechanical flap(s) to regulate intake air temps. (warm it up faster). A year later they went to a paper filter. I was told it was for ease of servicing and was cheaper to make.

I still run oil baths on both my 49 Stovebolt and 72 ACVW.

Dave

All three points are correct.

They are also a little harder to clean/service, but you get used to it.

I partly agree, it's cheaper to use the better filtering of the paper filter and save the warranty claims from scored cylinders that come from the oil bath. During the era of oil bath filters an engine would usually need a ring job by 50,000 miles and a complete rebuild by 80K. Today's engines regularly get well over 200K before needing serious work. Part of that is modern oils but part is also better air filtering. Scored cylinders come from dirty oil which comes in large part from dirty air in the cylinders.

It would be nice to see a scientific comparison of the 'cleanness' of the filtered air between an oil bath filter and a modern paper filter to see who's assumptions are correct.

After weighing everything, for me, to make the engine last longer, run cleaner, and easy to maintain, the PCV system, Original air cannister (modern air filter), and good modern synthetic oil. Its just how I roll. The hope is for the engine to last longer with all of those dirty exhaust gasses being vented, modern air filtration and oil is good insurance. It may be controversial, but I feel comfortable with my research.

On the 216s and the pre-'55 235s, I would blame the road draft crankcase ventilation system for introduction of dirt into the engine before I would blame an oil bath air filter.
As air is sucked out of the crankcase via the road draft tube, the dirt is drawn directly into the crankcase through the slots in the valve covers.
The vast majority of the dirt which may get past the oil bath air filter will be purged from the engine through the exhaust. Only a small percentage of the dirt will remain on the cylinder walls.
Carl

I never understood why GM thought that was a good idea, leaving slots in the valve cover where underhood grime can just enter whenever. I suspect it was a major cause of early engine failure.

Disposable paper air filters and PCV systems have more than tripled the expected life of engines. I can remember seeing the remains of Oldsmobile engines returning to Nashville from the Daytona race in the mid-1950's with half an inch of sand in the oil pan- - -that much had gotten past the piston rings after getting through an oil bath filter in 500 miles of racing on the beach.

A Detroit Diesel field engineer who was conducting a seminar for houseboat owners I attended was asked a question about "How long does a Detroit engine last?" His answer- - - -"Long enough to eat 10 pounds of dirt!" That can be 6 months, or 60 years! Keep 'em clean!
Jerry

As soon as I get another project out of the way, I am going to set up the filters for oil just as they should be. I may look at putting some paper filter material in the neck of the housing and see if it traps dirt or just oil. I have some unused paper filters I can cut up. If it looks like the paper is getting oil to quick I can always convert to dry elements.

Lots of information here I had not thought of or new about,

Thanks guys,

Joe

K&N is basically an oil bath cleaner without the puddle of oil at the bottom. The the mesh may stop large particles, but the oil is holding the vast amount of the dirt. Without the pink oil, its just a really bad cloth filter... the oil does all of the work.

I have both wire and horsehair oil bath air filters and they both work fine.. the motors they have been attached to are still running (I know that means little).

I read a stat that the average age of a car in the US is over 11 years old... that means that there are cars on the road significantly longer than 11 years (my Jeep ZJ is 18 years old, 172000 miles).

I think the biggest advancement in engine life was detergent motor oil. PVC systems are as old as detergent oil, but detergent oil was not really standard until the 50's.

What does plastic pipe have to do with engine life?
Jerry

I use a modified pvc delivery system so I can add detergent to my oil from a reservoir in my glove box when I run on dusty back roads...

As long as it was Borax (with the 20 mule team) I am down with it.

Poly Vinyl Chloride for us slow lorax (look it up, they're cute but slow) stovebolters.

For those who haven't caught on yet. Jerry's remark was about PVC being plastic and PCV being crankcase venting. I caught the humor anyway.

Yep, if you're going to masquerade as a know-it-all, at least try to get your abbreviations straight!
Jerry

BS speculation and/or opinions better suited to the Greasy Spoon?

The biggest advancement in engine life 70s-and-later is Japanese engines designed from "ground up" to meet pollution and mileage standards. Eventually, US manufacturers had to compete.

Modest improvements in domestic-use pre-70s engines' lives could be had, if you regularly changed an oil filter and an air filter.

Move this/my irrelevant post to the Greasy Spoon or delete it.

Thanks,

I can recall when the Japanese auto invasion hit full steam. I was working in a little neighborhood garage and we all thought that these little Japanese 4 bangers would eventually fly apart having to spin fast enough to run on our interstates.
We hardly saw an import come in for service and they didn't fly apart either......

A well maintained V8 was considered worn out at 100k but those little import 4 bangers were getting 150k+ and keeping their value.
Detroit got schooled by their best pupils.

Dave

"And many consumers couldn’t afford it, and didn’t have easy access to credit, especially if they had subprime credit. Accordingly, the age of the average vehicle on American roads hit 11.4 years earlier this year, according to an IHS Automotive study based on Polk Co. registration data."

Yeah.. COMPLETELY made up number... based on actual car registration data. Do do know of this thing called GOOGLE?

And the PVC addition was much wildly more successful than the PCP modification that lasted only a few years.

KNOWING is all and being able to SPELL it all are completely separate matters.

The problem with the IHS survey numbers is they only go back to 1995...

pCVarber,
PCV, PVC. Who cares? Your response to it only makes others smell victory. Personally I meant no harm. I make that same mistake 50% of the time. Its almost like Tourette syndrome (had to Google the spelling for that too).
Carl