Oil Bath Air filter, The Advantages.

[Blknight.aus]

Bit slack today but after some other foolishness like fixing the glow plugs I decided to service the air filter.

This was cleaned the week before the cape york trip (re CCCCC) and saw all of cape york and the major dust storms that hit the switch as well as some other twaddling around.

pulled it and checked the air trunk

https://www.aulro.com/afvb/images/imported/2009/11/866.jpg

a slight slick of oil which Im happy with because thats whats ment to happen if the filters working right the important thing is that its clean oil.

pulled the filter apart and
https://www.aulro.com/afvb/images/imported/2009/11/867.jpg
the first filter element, with just a little bit of dirty oil on the lips.

followed by the filter pan
https://www.aulro.com/afvb/images/imported/2009/11/868.jpg
say it with me...

EWWWWW.

and under the oil...
https://www.aulro.com/afvb/images/imported/2009/11/869.jpg

once that sludge came out, look I have a dimple in the bottom of the pan, that dimple is the best part of 3/8th of an inch high and when I weighed the pan after I scraped the crap out it was some 200grams lighter.
https://www.aulro.com/afvb/images/imported/2009/11/870.jpg

and finally after washing everything with solvent and letting it dry out
https://www.aulro.com/afvb/images/imported/2009/11/871.jpg

the pan ready to be placed back on the bottom of the filter once the first stage is put back into the pan.

Total cost $2 worth of cheap oil and about 20 minutes of my time. (including stopping several times to clean up enough to be able to use the camera.

The main advantages of this kind of filter are that they are essentially self cleaning while in operation and it takes a stupid amout of dust to actually clog them to the point that they start to restrict airflow.

[streaky]

I couldn't agree more. I had an oil bath filter on my Series III is Saudi Arabia....it kept the engines internals free from the nasty fine dust that contributes to any engines early demise.
My VW variant also had one....same results.

Re-usable/cleanable filters are great for DIY maintanance on long trips too.

[Rangier Rover]

I have to agree there. Of all our tractors and 4X4s. The old landy's and early ford tractors only essentially need the oil bath doing every 6 to 12 mths here before any problems, the paper type is every 2 to 4 wks as clog up:mad: The oiler is a bit more restrictive and may not get all the fines some seem to think. I have never tested this theory though. All I can say is the old tractors here have done over 16000 hrs on a set of liners so oil bath cant be that bad:) Electrolysis seems to kill them 1st:(

[Blknight.aus]

properly designed oil baths dont let anything through and arent as restrictive as some paper element filters.

The biggest problem with them tends to be when you need to shift buckets of air through them they can bubble the oil up and reduce the effectiveness if you run at high air flows for prolonged periods. Initially this bubbling and frothing action helps the filtration but eventually the oil level in the pan gets so low that it cant dump back to drop the muck out of the elements and they start to clog or worse the muck complete with the oil gets lifted into the engine.

[isuzutoo-eh]

Great post, think I found my project for tomorrow evening :)
-Mark

[Rangier Rover]

properly designed oil baths dont let anything through and arent as restrictive as some paper element filters.

The biggest problem with them tends to be when you need to shift buckets of air through them they can bubble the oil up and reduce the effectiveness if you run at high air flows for prolonged periods. Initially this bubbling and frothing action helps the filtration but eventually the oil level in the pan gets so low that it cant dump back to drop the muck out of the elements and they start to clog or worse the muck complete with the oil gets lifted into the engine.

I guess hi air flow shouldn't be a big problem with the 2.25 oil burner:p:angel:
I have often wondered why some of the smaller agricultural stuff has moved away from the oil bath. Cost maybe?

[Blknight.aus]

yep, the initial manufacturing cost of an oil bath filter is at least 10 times that of a blow moulded plastic airbox.

funny one of the rice boys wanted to know what it was while I had the hood up and wouldnt belive me when I told him it was an oil bath filter. he insisted that the wet sponge he had as an air filter was an oil bath filter.

[Rangier Rover]

yep, the initial manufacturing cost of an oil bath filter is at least 10 times that of a blow moulded plastic airbox.

funny one of the rice boys wanted to know what it was while I had the hood up and wouldnt belive me when I told him it was an oil bath filter.
he insisted that the wet sponge he had as an air filter was an oil bath filter. And you did tell him it was only a large bug filter right:D

[Blknight.aus]

no but he wasnt happy with me when I cut it in half to show him the sunlight in it...

[Bigbjorn]

And you did tell him it was only a large bug filter right:D

Bird strainer more like.

[llandro]

Living in a dusty environment our old s1 petrol did 230000 miles with the oil bath air filter and still showed the chrome at the top of the bores.
'76,S111 (2.25d) still plugging along, gets its filter cleaned out every couple of years.
Disco 300tdi needs the paper element blown out every 3 months. However I reckon the oil film which builds up in the intercooler and inlet plenum works like a secondary filter. I flush these at the same time as the filter clean and the oil residue always feels slightly "muddy".
llandro

[isuzurover]

I will need to test a couple of auto air filters mid 2010. If someone in Perth has a series oil-bath filter they can lend me for a week or two I would be happy to include it in the test.

[Pedro_The_Swift]

That'll stir the possum Ben!!:cool:

[TonyC]

I will need to test a couple of auto air filters mid 2010. If someone in Perth has a series oil-bath filter they can lend me for a week or two I would be happy to include it in the test.

Hi Ben,
If you don't get a local Land Rover one, I'll post over the one out of my Haflinger. It's only a little one, feeds a 650cc twin.

Tony

[Blknight.aus]

if no one else has one I have several spares and am more than happy to drain clean and post one over to dads place as part of the family xmas pressie so it can be included in testing.

[defend]

What where the last Land rovers to use the oil bath filters,these seem much better than the paper filters but i think the cost of a "modern" paper filters is a cost saving for the manufacturers,plus you have to buy new paper element filters so more profit for the manufactures.With the oil bath type the manufactures make nothing off you.So my conclusion is that the oil bath filters are superior in dusty,dry climates(Australia) than the modern paper filters.The marketing of the paper air filters to the public as modern/better,is like the old video players,where the public were sold the inferior VHS system,when the Beta system which was light years better was thought by most people to be a dud.Anyway,i now will have to find and fit an oil bath filter to my Defender as when i was younger my Peugeot had them and i had long forgot about there effectiveness until this posting.

[JDNSW]

What where the last Land rovers to use the oil bath filters,........

Pretty sure it would have been the last Series 3, produced in about 1985, although it is possible the first 110s with the 2.25 engine retained them - but these were never sold here, only the V8 and Isuzu, both of which used paper air cleaners.

John

[djam1]

I would like to see the results of the tests I always swore by them but gained a healthy respect for Donaldson Paper filters used on tractors.
I have driven a tractor many hours with a maximum visibility of a few metres for hours on end we never dusted an engine with the Donaldson.
I recall being concerned about about the oil bath aircleaner on a Cat D7 of the 40s vintage with its very find dirt in the air intake pipes (never hurt the engine though)

[windsock]

Pretty sure it would have been the last Series 3, produced in about 1985, although it is possible the first 110s with the 2.25 engine retained them - but these were never sold here, only the V8 and Isuzu, both of which used paper air cleaners.

John

I can confirm that one about the early 110's. I have a 1984 110 here in NZ and it had a 2.25 litre petrol engine breathing through an oil bath filter. I removed it as it was going to be too difficult to fit it with a snorkel as the intake was through 'fluted' openings at the top of the filter. With a welder and some thin steel I guess I could reinstall it inline with the snorkel. Good informative thread.

[JDNSW]

I can confirm that one about the early 110's. I have a 1984 110 here in NZ and it had a 2.25 litre petrol engine breathing through an oil bath filter. I removed it as it was going to be too difficult to fit it with a snorkel as the intake was through 'fluted' openings at the top of the filter. With a welder and some thin steel I guess I could reinstall it inline with the snorkel. Good informative thread.

What you need for a snorkel is the aircleaner of an 80" with the precleaner sticking out the side! But what you could almost certainly do is remove the top bit of the air cleaner with the slots and fit the elbow that normally goes on a carburetter with a hole drilled for the threaded rod that held the top on and some silicone to seal it.

John

[101 Ron]

To tell if your oil bath filter needs servicing just look at the oil fill line.
If it is over full the filter needs cleaning as the dust displaces the oil and the oil level rises.

[scompt01]

I just bought a Series 3 with an oil bath filter. I removed it last night for the first time to give it a clean. When I remved the hose from the carby, Zenith, a small amount of oil actually came out the end of the hose. Is taht normal? Any ideas? Thanks.

[JDNSW]

Indicative of use on a very rough road, overfull with oil or if it is one with the breather feeding into it, is most likely due to engine blowby pushing oil from the rocker cover into the intake.

John

[Pedro_The_Swift]

Are you still out there Dave??

would be REALLY interested in a vid of one in action--

you seem to me the kind of guy that could do that;):D

[pfillery]

I swapped the air filter (oil bath type) out of my series 3 for a paper element and it made it run really badly, would stall all the time and was harder to start. Swapped it back and it was much better. I don't think I'll get rid of it now.

[isuzurover]

EDIT - I haven't yet had a chance to test the filtration efficiency of these things, however:

Commercial Oil-Bath:

Laboratory tests with various types of dust show efficiencies ranging from 95.4% to 98.6%.
http://www.fallsfti.com/prod_oilbath.htm

Cellulose or polymer fibre elements:

» Donaldson Air Filters in Donaldson Air Cleaner housings have a 99.95+% minimum overall efficiency.

» The efficiency of the filter actually improves as dust loads up on the surface of the filter; so an air filter gets better as is gets used.
http://www.donaldsontoolbox.com.au/air-filter-efficiency.html

Those numbers are what I would expect, and will mean quite a bit more dust getting to your engine over its lifespan if using an oil-bath filter over a (paper) element type filter.




I swapped the air filter (oil bath type) out of my series 3 for a paper element and it made it run really badly, would stall all the time and was harder to start. Swapped it back and it was much better. I don't think I'll get rid of it now.

Maybe your engine needs the oil droplets blowing off the oil bath to run properly :D Seriously, you may have issues with your carby or with air leaks.

[Blknight.aus]

well you could see the vids from the cape trip... but the easiest way to see one in action is to replicate one yourself....

you only need a bit of hose a bowl and a large cup.

fill the bowl with water, invert the cup into the bowl and then put the tube under the water up into the cup.

blow into the hose.

thats how they work, that simple.

[123rover50]

I will need to test a couple of auto air filters mid 2010. If someone in Perth has a series oil-bath filter they can lend me for a week or two I would be happy to include it in the test.

Did this get done?
We were discussing paper filters in another thread recently.
I mentioned I like oil bath.
Perhaps with a turbo I may need to source a larger one:o
Keith

[123rover50]

Double post. Firefox doing funny things

[isuzurover]

Did this get done?
We were discussing paper filters in another thread recently.
I mentioned I like oil bath.
Perhaps with a turbo I may need to source a larger one:o
Keith


No, not yet. However did you see the quotes above from manufacturer websites?

Happy to still do it if you have one to lend...

I have just spent the last few days on farms doing measurements on (modern) farm machinery. Not an oil bath filter in sight on the new stuff... However there are still quite a few chamberlains still in use with oil baths...

[JDNSW]

........ However there are still quite a few chamberlains still in use with oil baths...

Interesting - my Chamberlain is 44 years old; and has a paper filter! I wonder when they changed?

John

[Blknight.aus]

the first paper filer I recall seeing was on a stationary engine from the thirties...

To change it you pulled out these big panels double sided panels that were wedge shaped (like a very shallow V) removed the paper from the outside and then re wrapped the frame in what looked to be toilet paper.

There was 2 of them with the mother of all butterfly valves fitted over the top of the joiner pipes, IIRC you changed over from one filter to the next every hour or so and the vibration from the machine was supposed to let the crud fall away from the paper on the filter that wasnt drawing air. at the end of the day (might have been shift change/service interval) you changed the filter

[101RRS]

My Haflinger has, in order of filtration, a cyclonic filter, then an oil bath and then a paper filter - so in theory at least, no crud should ever get through to the engine.

[slug_burner]

Sounds like the order might indicate the filtration ability. Cyclonic for the bulk of the heavy stuff, oil for the rest and paper for the stuff not filtered by either of the other two.

[Kev the Fridgy]

Slightly off topic, but.... I remember cleaning Oil Bath return air filters in and around Brisbane as an apprentice. I for one am happy the HVAC industry moved to disposable paper and fabric filters

Really....really....really happy

[Blknight.aus]

jsut remembered something......

I cant remember who or exactly where but the conversation was with some older guy (might have been one of dads friends Im pretty sure he was a mechanic or attendant at the place we were staying) who was getting ragged on by some yota drivers because of his oil bath filter.

His reasoning was. The oil bath filter is reusable and repairable, what happens if you drown a paper filter?...

muprhyishly, one of the yota nuts had cowboy-ed a water crossing and drowned the engine while out and about and upon being towed back in with no major damage to the engine the air filter was stuffed from water damage so the choices were wait for an appropraite filter, find something to bodge it with or drive back over umpteen miles of gravel roads with no air filter.

[350RRC]

Hi gents,

I have a MF 165 tractor and a Howard rotary hoe with oil bath filters. The efficiency of dust removal compared with paper interests me.

One aspect of oil bath filters that has not been touched on here is why the dirt ends up in the filter bowl.

Sure some of the dirt comes out as the air passes through the oil.

Incoming air also draws frothy oil up into the metal gauze matrix where dust sticks. After shutdown the oil (and dust) in the gauze drains down into the bowl and the dust settles out.

I suspect this leads to much longer service intervals than paper.

cheers, DL

[JDNSW]

.....
I suspect this leads to much longer service intervals than paper.

cheers, DL

I think this is going to be impossible to quantify, as it is impossible to say which oil and paper aircleaners are equivalent. Recommended intervals may be quite different to what the filter is actually capable of - remembering that the manufacturer has no way of predicting what conditions you operate in. As an example though, my 110 has a recommendation to replace the paper element when the restriction sensor is triggered - typically 20-50,000km. My Series 2a recommends cleaning the oil bath filter every service (5,000km).

The oil bath filter costs about $10 to service for washing fluid (kerosene) and oil, the 110 filter costs around $60, so costs are comparable.

John

[isuzurover]

...
One aspect of oil bath filters that has not been touched on here is why the dirt ends up in the filter bowl.

...

Almost all dust separation in an oil bath happens when the air turns a sharp corner at the bottom of the air filter (or bubbles through the oil depending on design).

The "element" in an oil bath filter is too coarse to capture any significant amount of dust. It is just there to catch oil droplets and return them to the base/bowl.

[chazza]

The "element" in an oil bath filter is too coarse to capture any significant amount of dust. It is just there to catch oil droplets and return them to the base/bowl.

Not forgetting that it also catches moths, grass seeds, etc. - well it does on my tractor :D

[scarry]

Slightly off topic, but.... I remember cleaning Oil Bath return air filters in and around Brisbane as an apprentice. I for one am happy the HVAC industry moved to disposable paper and fabric filters

Really....really....really happy

But then they went to those gell covered bags.Bloody good at filtering,but a messy PITA to change:mad::mad:

In fact those gell covered filters were the best A/C filters available,the whole system stayed perfectly clean.

[scarry]

jsut remembered something......

I cant remember who or exactly where but the conversation was with some older guy (might have been one of dads friends Im pretty sure he was a mechanic or attendant at the place we were staying) who was getting ragged on by some yota drivers because of his oil bath filter.

His reasoning was. The oil bath filter is reusable and repairable, what happens if you drown a paper filter?...

muprhyishly, one of the yota nuts had cowboy-ed a water crossing and drowned the engine while out and about and upon being towed back in with no major damage to the engine the air filter was stuffed from water damage so the choices were wait for an appropraite filter, find something to bodge it with or drive back over umpteen miles of gravel roads with no air filter.

In the mid 80's,one of my brothers worked in Weipa for many years,and had a SWB series three.One night he was driving back home and went through some deep water and the oil in the filter went through the engine.Didn't even see the water until he hit it...

No problems at all,apart from the fumes that the exhaust emitted into his mate who was in a tojo that was following....:D

[350RRC]

Almost all dust separation in an oil bath happens when the air turns a sharp corner at the bottom of the air filter (or bubbles through the oil depending on design).

The "element" in an oil bath filter is too coarse to capture any significant amount of dust. It is just there to catch oil droplets and return them to the base/bowl.

Thanks for the reply. The following is a quote from a US tractor site:

'Oil bath filters are probably one of the most neglected parts on a tractor. They work by the oil bieng pulled up on the mesh and then the dirt gets trapped on the oil and then the oil drains back down off the mesh when the engine is shutdown and the dirt settles in the bottom of the oil cup.'

Makes sense to me for the following reasons:

1. All the oil bath filters I've come across (VW, MF and Howard) use a gauze that you can't see daylight through even when freshly cleaned in solvent.
i.e. dirty air has no direct route through an oily maze in normal operation.

Seems like the K&N principle, except 'daylight' is not involved and the gauze is self cleaning to some extent (moths and grass seeds excepted, not enough mass for surface area to unstick) by gravity on shutdown.

2. If the gauze is just there to catch oil droplets why did the designers not use a simple fine one layer mesh?

Be interested in thoughts on this.

cheers, DL

[isuzurover]

Thanks for the reply. The following is a quote from a US tractor site:

'Oil bath filters are probably one of the most neglected parts on a tractor. They work by the oil bieng pulled up on the mesh and then the dirt gets trapped on the oil and then the oil drains back down off the mesh when the engine is shutdown and the dirt settles in the bottom of the oil cup.'

Makes sense to me for the following reasons:

1. All the oil bath filters I've come across (VW, MF and Howard) use a gauze that you can't see daylight through even when freshly cleaned in solvent.
i.e. dirty air has no direct route through an oily maze in normal operation.

Seems like the K&N principle, except 'daylight' is not involved and the gauze is self cleaning to some extent (moths and grass seeds excepted, not enough mass for surface area to unstick) by gravity on shutdown.

2. If the gauze is just there to catch oil droplets why did the designers not use a simple fine one layer mesh?

Be interested in thoughts on this.

cheers, DL

Your quote is incorrect and/or far too simplistic.
Have a read here for starters:
http://www.tsi.com/uploadedFiles/_Site_Root/Products/Literature/Application_Notes/ITI-041.pdf

This is about filters, but the same physics apply.

[chazza]

Top link Ben, thanks for posting it!

As a relevant aside; I was recently researching what filter medium to use on my sports car, which came to me with no air filters. One site I visited was about the importance of increased oil changes in very dusty environments; in this case northern Africa.

Because of the 0.1 - 0.4 micron particles getting through the air cleaner, the mining machinery was wearing out engines far too quickly. The solution was to change the engine oil much more often - the report didn't specify how often - but I could imagine maybe 4 x.

Changing the engine oil has often been quoted as the cheapest form of maintenance, and compared to the cost of a new engine it still makes sense to make it a priority,

Cheers Charlie

[350RRC]

Your quote is incorrect and/or far too simplistic.
Have a read here for starters:
http://www.tsi.com/uploadedFiles/_Site_Root/Products/Literature/Application_Notes/ITI-041.pdf

This is about filters, but the same physics apply.

Thanks for the link which is very informative re: fibre filters. It is obvious that modern paper filters are superior for removing finer particles.

My interest is in how oil bath filters really work and why they are all essentially the same design.

This Mann Hummel pdf has some relevant info on oil bath filters and their application:

http://www.krone-filter.de/files/pdf/oil-bath-air-cleaners-from-mann-hummel.pdf

This is a quote from the pdf:

'Design and principle of operation

Intake air is routed via the oil bath. There the coarse particles are removed from the air and the air is rerouted upwards. As the air streams
upwards, oil from the oil bath wets the filter packing and the dirt in the intake air is deposited there. The oil flows back to the bath where the dirt settles.
The oil bath achieves a maximum separation efficiency of approx. 98.5% and is therefore not as efficient as the filtration performance of a modern dry air cleaner (> 99.95%).'

And servicing interval from the same doc:

'The servicing of the oil-bath cleaner should be carried out at the latest when the deposited dirt has reached half the height of the oil level or if the oil has become thick.'

Now that is a lot of dirt if one considers than their oil bath filters hold up to 5.5. litres of oil.

cheers, DL