The Stovebolt Site Forums The Shop Area Engine Shop Oil bath air filter. But why?

Ok, again I checked the search engine, but didnt find my answer. (Am i not searching right or am I really coming up with original questions! :)=) Or am I the only one here who doesnt know the answer to my questions hehehe

How does an oil bath air filter work, did you have to keep adding and changing out the oil yourself?

What was the engineering mindset behind this type of filtration?

Does everyone/anyone still use theres on there truck?

57Rat,

The oil bath filter requires the incoming air to make a drastic 180&deg turn inside the filter housing. The air can do this, but any particulate matter, anything with weight, keeps going straight..splash!, right into the sticky bowl of oil.

The filter is serviced at regular intervals by dumping the old contaminated oil and refilling with fresh.

Dry filter technology wasn't around in the good old days, and it is still thought that a properly engineered oil bath is superior to a dry filter...as least with some folks.

I don't know who still uses these big old beasts, maybe purists do.

Stuart

Hey, thankx for the quick response, I am new to this site, and I am always surprised by how quickly questions get gobbled up and spit back out so quickly! So surprised in fact I sometimes sit and wait for my answer, Im getting spoiled! But I think my wifes getting irritated, hehe

Hey, theres nothing wrong with a purist, Not that you said there was, but there the guys we all hope for when we got the tough questions or need the tuff parts!

There is a bit more to the operation of the oil bath air cleaner. In addition to what Stuart posted, there also is a "misting" action that is happeneing, caused by the way the air flows throhg the housing. Thsi oil mist also traps dirt, namely the fine particles that do not end up in the pool of oil in the bottom of the housing. Thsi mist is collected on a fine wire mesh located in the housing, then returned to the reservoir, along with the trapped dirt.
A modern dry filter may be more efficient at trapping dirt, but an oil bath will not clog up, and properly maintained, are as efficient if not more overall. If you look at them, almost all big rigs still use the oil bath type air cleaner (the big chrome tank located next to the front of the cab) because of the low restriction of that type.

There have been some long and heated threads debating which is "best", the oil bath or modern dry element. I'm on the dry element side. It's been a few months since the last blow out. It'll be interesting to see if this becomes another.

I won't say one is necessarily better than the other, alot would depend on what type of use the vehicle sees. For myself, I'm in the middle, as I use K&Ns .

Back in the early 1950's, one of the shops in Nashville that was in competition with my father's shop built some Oldsmobile engines for the Daytona race, back when they were still running on the beach. Those engines were equipped with the best oil bath filters they could find, and all of them came back with a noticeable layer of sand in the oil pan. That much had gotten past the filter, and the piston rings. The engines were totally worn out from abrasive damage after 500 miles. I'll stick with my paper filter!
Jerry

My '58 has 102k miles on it with the original oil bath filter and is still running strong. Of course, I don't race it down the beach.

Hi 57rat,

Welcome to the site.

I always heard that the oil bath air filteration system was like 95% or 98% efficient. I have always used them especially if I was lucky enough to have one equipped with a new vehicle purchase or found one available for my particular application. The big plus is, they are easy and cheap to maintain and I think they look way too cool. Just my opinion.

If you are thinking of a replacement, spend the extra money and go for the K&N as was mentioned above here already. They are without a doubt among, if not, the best replacements available.

Dave

The main problem with the paper element type of filter is who and where it is made and the size of the unit. The small "Made in China" element filters and the small diameter chrome holders they make can tend to choke down your engine just enough to not be noticible, but enough to cause your engine to run rich and disrupt the gas milage you expect to have. Eventually the plugs fowl and the truth is known. With a proper oil bath air cleaner, this problem can usually be avoided due to the fact that they are sized correctly and air restriction is not an issue.

Joe

I took my oil bath housing to my FLAPS & got a modern full size filter to fit. I couldn't tell you what it's made to fit but I think I have the number in the garage.

Tiny,
I would like to see a photo or explanation of your oil bath filter with the dry filter in it. I cannot imagine how you did that! I have heard of people putting a modern day dry filter in the original dry filter housings.

Check your e-mail.

I would like to see it too, Tiny. Another question if you replace the oil bath with a decent paper element type, is there one that looks halfway decent? I really don't like those 6 inch diameter chrome types.

Aww, they're not that bad!
http://rides.webshots.com/photo/2791114620092261295pSVaee

Bill,

Nice truck...love the junk yard pix.,especially that Detroit diesel!!!

Dave

I've still got an oil bath on my 216.

I keep it there partially becuase I'm a purist, partially because the way I drive it, heavy dust is generally not an issue, and partially because I like being different and surprising the old guys with it.

If you're racing down the beach, I'd spring for a paper element.

If you're driving it under normal (read: road) conditions, then either should be fine.

Check your e-mail olblu49.

Thanks.

I read these post about oil bath air filters. I have one for my 283 powered 57 chevy 3100 pickup. I have been afraid to use it much as I had heard once that they are prone to fires.

I did occassionally get a backfire through the carburator (have not noticed it in the last couple years since putting a pertronics in it) so I do worry that it may catch fire. Is there any truth to that rumor?

I have thought about trying to convert it some how to use a paper filter internally. I like the look of the big old oil bath filter but worry about the chance of fire.

As a result I usualy run with a cheep 6 inch filter in place of the big oil bath one.

Any suggestions.

I use a paper air filter that fits perfectly inside the oilbath housing. The paper filter is a "Wix Filters" part number: 42011 There are pictures in my photo link if you are interested in looking at it.

I still have mine, because I see no reason to replace it. Around here, a lot of the roads are gravel(when I can drive it on the road) and the oil bath air filters were ideal(from what was in the shop manual) for driving on dirt roads. As far as it catching on fire, they are supposed to act as spark arresters. Plus oil doesn't burn fast like gas does. I'd let someone who actually knows what they are talking about explain it though.

svwilbur, I've driven thousands of miles with oil bath air filters, and I would say that the chance of a fire is minimal, unless you fill the filter with gasoline.

Yessirree, gents, the military M-151 (almost a) Jeep used oil bath air filters at least as late as 1986, and probably later. I think the HMMWV was the first Jeep sized vehicle that used a paper filter, but I never drove one, so they might be oil bath as well.

Most of the farm trucks and farm tractors around here have been using oil bath air cleaners for years. Sure keeps that fine dirt/sand out of the engine. I feel the fire hazard is small.

From the 1954 Chevrolet Truck Shop Manual: Look at the bottom of this page and on the next one. It explains all about the oil bath air filter, and it says that both models use incorporate flame arresters.

If you have a Rochester B carburetor get rid of the whole thing (oil filled) as they are too HEAVY and will wreck your carburetor. Go with the early style copper mesh and throw that copper mesh away as it will (in time) break down and go straight into the carburetor. Replace it with a paper cartridge replacement from Napa. UNK.....70 yrs. of experience talking!

There is nothing wrong with oil bath air cleaners under the hood. However paper air cleaners are easier to service. I have been operating over the road trucks since 1964. Oil bath air cleaners were phased out in the late 60's and early 70's because no matter where they were installed, water would get in them and the oil would emulsify and the level would rise to the point that airflow was greatly restricted. The same thing happens with old farm tractors. If they sit outside in a driving rain, water gets in the air cleaner. The large cans on the side of some conventional trucks are vortex air intakes, not oil bath filters. They are very expensive and see limited use with owner operators who like chrome. Pleated paper filters have been the standard for many years. But under the hood on older vehicles where water is not a problem, it is up to the owner's preference. Maintenance is the key factor in either system