Oil bath air cleaners

[Texan4Life]

Has anyone ever tested them using modern standards (or any kind of testing)?

Word on the street is they had extremely good filtering capability. But fell out of favor due to the easy maintenance of paper.

I wonder how one would stack up against modern paper filters?

 

[JustinC25]

My Grandpa's (Soon to be sold) 1942 Dodge Business coupe has one.

 

[Eddie]

I did read a paper many years ago (~ 1955?) published by the Society of Automotive Engineers. The conclusion was that the newer paper filter were much better in all aspects.

 

[paulo57509]

IIRC, oil bath air filters didn't filter very well at low engine speeds (low air velocity) but filtered well at high engine speeds (high air velocity).

I used to like to service oil bath air filters. I got to play with engine oil.

 

[edhackett]

Oil bath filters are pretty good at everything an air filter is supposed to do except for removal of fine dust. A good paper filter is much better at removing fine particles.

Ed

 

[Steve S]

Paper is way better.

 

[Jim Allen]

Originally Posted By: edhackett
Oil bath filters are pretty good at everything an air filter is supposed to do except for removal of fine dust. A good paper filter is much better at removing fine particles.

Ed


Ed Hackett. THE Ed Hackett? Didn't you post a paper some years back from the "Desert Research Institute" using the J726C Test Method? I have that in my files. It shows that the oil bath were the worst at small particle filtration and second worst in airflow. That was quite some time ago, as I recall. I did some airflow testing of a couple of different oil baths long ago and found them abysmally restrictive, but I guess that would depend on which unit was used on what engine. The ones I tested flowed barely enough for the stock engine. Interestingly, flow could be increased slightly by reducing the oil level. That would likely have had an effect on filtering efficiency, however.

I would dearly like to see the nitty-gritty (pun intended) on those tests and know which filters were used, plus the actual numbers. Did you have that info or just the 1-5 ratings you posted?

 

[edhackett]

Never say anything on the internet, it will haunt you forever.

Here is a link to the original posting: http://www.roadkill.com/~davet/moto/air.filters.html

We didn't do the tests. The data came to me from an ex-GM engineer that was working on an emission study with us. I don't know where the original data came from. It's at least 20 years old, and the engineer moved on a long time ago.

Advances in paper media have certainly improved the performance of paper filters. I still would choose an oiled foam above a K&N, and paper above both. I don't think the oiled foam are really as good as shown in the chart, based on experience.

I think the design of the oil bath does have a lot to do with it, as does the weight of oil used and the ambient temperature. The one on my John Deere has a relatively shallow oil pan and a tall coarse "steel wool" element. It doesn't appear to be terribly restrictive. It's certainly kept the old beast alive for 69 years of working in dusty fields.

Ed

 

[widman]

I have several UOA that show oil bath air filters will give you ten to twenty times the dirt and iron.

They were using Delo Synthetic 5W-40 in the engine and the filter.
here is one

 

[Big_Ed]

The best thing about an oil bath filter is there's no searching and searching for a correct element to put in the air cleaner. Kind of nice when servicing my Dad's '57 Hudson Hornet. Parts can be kind of hard to find. Many times when we find parts for it, we buy 2 or more just to have them on hand.

 

[Texan4Life]

Quote:
It's certainly kept the old beast alive for 69 years of working in dusty fields.


thats whats got me thinking. My dad would talk about cleaning an oil bath air cleaner on a 1960's combine once a day and it would turn fresh oil into goo.

but then again I guess old iron had bigger clearances than today's engines.

 

[edhackett]

Yep, daily servicing of the air cleaner was necessary for it to clean properly. John Deere calls for servicing the air cleaner every 10 hours.

The clearances were pretty much the same as now. Here are the specs for my 1941 JD:

Piston to bore: .004-.007
Piston pin: .001
Main and rod bearings: .003
Crank end play: .005-.007


A modern Chevy V8:

Piston to bore: .005-.006 (big block)
Main and rods: .002-.003
Crank end play: .0065

The old iron was more tolerant of wear. The bits were large, they ran at relatively low RPM, low power density, and had design features that helped mitigate minor wear. For example the pistons on my JD look like coffee cans with three rings on the front and one on the back of the piston. They wouldn't develop slap as they wore, unlike modern auto engines that often slap out of the box. It also has full flow oil filtration and the oil pressure is externally adjustable.

I get a kick out of adjusting the crank end play. You loosen the flywheel clamp bolts, lock the clutch, put a piece of wood against the flywheel, and smack it with a sledge hammer. Setting clearances that are thousandths of an inch with a sledge hammer makes me giggle.

Ed

 

[Gary Allan]

Originally Posted By: edhackett
Setting clearances that are thousandths of an inch with a sledge hammer makes me giggle.

Spock: I am endeavoring, ma'am, to construct a mnemonic memory circuit using stone knives and bear skins.

 

[hardcore302]

lol

 

[Seguino]

Originally Posted By: Gary Allan
Originally Posted By: edhackett
Setting clearances that are thousandths of an inch with a sledge hammer makes me giggle.

Spock: I am endeavoring, ma'am, to construct a mnemonic memory circuit using stone knives and bear skins.

My all time favorite episode!

 

[widman]

Here is the set of samples I ran on an Iveco with an oil bath and Chevron Delo 5W-40.

 

[GeorgeGear]

Sorry for pulling this thread back from the dead. I could not help noticing Ed Hackett's name too, like Jim... Ed - I have had this article in my notes probably for a good 10 years as well I even looked you up once at RDI to ask for your comments on that test, but I never called... I had the same reaction as Jim as I discovered this thread: THE Ed Hackett