Oil Bath Air Filter

[AustHaflinger]

When I got my Haflinger it only had the paper air filter. Having driven it offroad in dry conditions I can see why the additional oil bath filter was added and the tropical air intake system was made available later.

I bought a new air bath filter but only fitted it today. I filled the bottom to the marked level with engine oil and fitted it to the air intake. No problems.

Then the problems started - the engine would start and run OK but when driving the engine is strangled and will not drive up hills where more power is required. I removed the connecting pipe from the oil bath to the paper filter and all was back to normal so the oil bath is restricting air flow into the engine.

So - what have I done wrong?

I am thinking that if I connect the tropical intake at the front, the oil bath is not needed, so I might just join the pipework direct to the paper air filter housing if the the oil bath is problematic.

Thanks

Garry

[ogdenenterprise]

The photo of the engine bay pipework in the airfilter thread fits directly to the oil bath air filter with a short piece of rubber pipe and two pipe clamps , have you fitted a genuine oil bath air filter?

Dave

Just had a thought when I had my oil bath filter painted ,when I refitted it my engine would not run, eventually found the problem the painter had stuffed a rag up the internal pipe of the top or the filter so it was choking the air to the engine.

[AustHaflinger]

Yes - Dave is a genuine (well maybe a repro) supplied by a Haffie part seller and no rags in the intake.

Garry

[heinkeljb]

Gary,

I would remove the whole Oil bath filter system, open it up on the bench so you can see how the air comes in, goes through the various passages, etc.

I don't think the air actually goes through the oil to get in to the engine, so possibly there is some blocked passage way in yours that is causing a reduction in air needed by the engine when under load.
My assumption that you don't draw air through the oil might be wrong, but I would think oil is too thick to draw air through (in the quantity required) and that the oil is only there to trap any dirt that is dropped out of the air flow as it passes through the container.

A good paper filter in the last part of the air intake to the carb is going to do most of the filtering of dust and in dusty conditions any other vehicle will have a warning that it will need cleaning / replacing at more frequent intervals than the handbook recommends.

John

[AustHaflinger]

I have googled oil bath air cleaners and am getting mixed answers - some do indicate the air does go into the oil - in which case a very light oil would be needed.

Other references have the air going down the central tube and making a U turn over the surface of the oil. Heavy particles cannot make the turn and go into the oil where they are captured. When the air goes over the top of the oil it creates a disturbance and oil mist is picked up with the air rising up - as the oil laden air goes through the mesh, the mesh captures this oil now in the mesh which in turn captures the finer dust particles. I assume that this latter process is the one in the haffie.

Even though I only filled the sump to the line maybe that is a bit too much. I will pull it out in the next day or so and check it all out.

Garry

[heinkeljb]

I presume you used the same oil that you were putting in the engine? If so, then the oil is the correct "weight" for the oil bath and filling it to the first "lip" / marked line would be correct as well.

If there is a fall off in engine performance, then is has to be down to an air restriction somewhere in the intake system. Does your Hafi have both the paper element filter as well as the oil bath filter like mine?

I think taking the oil bath unit out completely and washing it clean completely will cure the issue - Remember that these vehicles are OLD and may not have had certain bit taken off and cleaned EVER in their lives. The complete oil bath filter unit strikes me as being one of those things people just don't bother with other than to take the bottom bit off and put some more oil in it if they bother at all.

John

[Julian B]

I am almost certain that the air doesn't actually go through the oil - certainly it does not look "aerated" when removed soon after stopping the engine. My understanding is that the oil is there to catch any particles that happen to been blown "near to" the surface of the oil.

I use normal engine oil in the oil bath.

[AustHaflinger]

I think taking the oil bath unit out completely and washing it clean completely will cure the issue - Remember that these vehicles are OLD and may not have had certain bit taken off and cleaned EVER in their lives. The complete oil bath filter unit strikes me as being one of those things people just don't bother with other than to take the bottom bit off and put some more oil in it if they bother at all.

John

The oil bath filter is absolutely brand new and has never been used - this was the first time it has been installed - yes It has both air filters but up to now just running on the paper filter without issue.

Garry

[AustHaflinger]

I am almost certain that the air doesn't actually go through the oil - certainly it does not look "aerated" when removed soon after stopping the engine. My understanding is that the oil is there to catch any particles that happen to been blown "near to" the surface of the oil.

I use normal engine oil in the oil bath.

Thanks - that is what I thought as well - I will remove a bit of oil and see if that improves things a bit.

Cheers

Garry

[heinkeljb]

Gary,

You could try using a vacuum cleaner on blow to force air in the intake side and see if you are getting any where near the same volume / speed coming out of the outlet side.

Did you open it up before you put it on? Maybe it has paint blocking hole or something? The depth of oil is some thing like 1 ~ 1.5cm to the level line so it is unlikely if that is how deep yours is to be the main problem.

Hope you get it sorted soon.

John

[ogdenenterprise]

Hi Gary ,Could I inquire if you sorted the air problem,if so would you enlighten us.
Dave.

[AustHaflinger]

Sorry Dave - no I haven't. I changed my springs this week and as it runs fine on just the paper filter and I am just driving around town there is no urgency to do it.

I also want to understand why the air intake on the oil bath is so much smaller than the intake to the paper filter which in turn is smaller than the top of the carby. It would seem the complete system is smaller than what the carby needs.

Then of course the exhaust pipe is so much smaller again.

Garry

[Tennmogger]

This thread has been around a while. Was there any resolution as to why the added oil bath filter restricts the engine?

An oil bath filter obviously should not provide any more restriction than a good clean (note clean!) paper filter. In fact, it will continue to provide free-flow air long after a paper filter would be plugged up.

Having been around oil bath filters all my life, the air path normally does go through the oil bath. The operation of an oil bath filter is quite elegant, actually. It does so much more than simply take out chunks that can't make the 'corner' in the filter. Incoming air is routed down through the oil, causing the oil to splash around and get drawn up into the mesh element in the upper part of the filter (think Brillo Pad). The element gets covered with oil and as the air meanders its way upward through the torturous route, each oiled Brillo strand combs the dirt particles out of the air. Excess oil washes the mesh continuously and carries the dirt down into the pan by gravity.

Oil bath filters work very well. Unimogs have them and even after working dusty fields there is no detectible dirt in the air intake tubes.

Humor me a moment with a little digression. I have an M-38 Jeep that has been 'restored' and modified so many times it is not military any longer. It has a paper air filter instead of the original oil bath. During my absence many years ago this Jeep got used to pull a harrow in dusty conditions and the paper filter was so poor that the engine oil turned red from the fine dust. I have never liked paper filters since then.

When I discovered that the Haflinger uses a paper filter AFTER an oil bath filter, I was bewildered at first. IMHO the oil bath is a much better filter, why follow it with another filter. Then after my manual arrived I think I realized why this was done.

The Haflinger paper air filter is called a "micronic" filter (users manual p.37). The implication is that it is a much finer filter than an ordinary paper filter. That's great, but why put it after the oil bath? Because a very fine filter will plug up very quickly if dirty air is coming to it! By placing the oil bath filter before the "micronic" filter, only filtered air hits the paper element where it gets it's final purification, plus, any fine oil droplets would be taken out, too.

So, without the oil bath filter a Haflinger's paper filter is getting raw dirty air. If it's an original filter the life should be short, the element will plug, and air flow reduce. If not an original filter then the flow may remain 'ok' but dirty air is reaching the engine.

Can anyone confirm the specs of the Haflinger filter? Is there a source on this continent? Is there a cross reference? (SAV could not provide one on my order).

PS, the reduced diameter of the passages through the oil bath are to gain air velocity, I think.

(This opinion is worth what you paid LOL)

Bob

[AustHaflinger]

Hi Bob - I should have updated this thread. The issue I had with the oil filter must have been a false diagnosis and was in fact related to carby issues I was having at the time. I now have the proper Zenith carby on it and other issues sorted - I have the oil filter connected before paper filter and have had no issues.

I am not sure I agree with you of the advantages of the oil bath over a paper filter. They are good but not that good. Landrovers started out with oil bath filters but changed over to paper filters in the late 70s. Likewise with my Jag I have oil soaked foam sport air filters and I have been told not to use them as they allow fine dust through that will polish the bores.

As far as smaller particles go in the oil bath filter they are supposed to be picked up by the oil soaked mesh - the logic being if there is a direct hit the oil traps them but also the charge on the particles is different to that of the oil so the particles are attracted to the oil and trapped. Works but only to a point - the very fine stuff still gets through hence the very fine paper filter. You said in your experience that dust gets through the paper filter then I would say that there was either another issue or the wrong grade of paper filter was being used. If it was being blocked at least it was doing its job.

In outback Australia we have very fine red dust that gets into everything. Vehicle wise the arid areas were opened up using 50s landies with oil baths and they worked but the paper elements used in newer vehicles like my FC101 and RRS work better. Just about all 4wd vehicles here now use paper filters - though many older tractors used on farms still have oil bath filters.

It was Haflingers use in these environments that highlighted the filtration with both systems was inadequate as the engine space sucked in so much dust it choked the system so the tropical inlet with the air intake at the front of the vehicle was installed on many Haflingers.

So my experience now is that both filters work well together and in addition I will connect up the plumbing so I get fresh air coming from the front. The last time I went offroad the amount of dust sucked into the engine bay was incredible.

Cheers

Garry

[heinkeljb]

Just to throw in another perspective:

Oil bath cleaner are an "old" technology -based on a time when things were made to last and were expensive to buy in the first place.
Paper filters were developed and produced in sufficient number to become a "cheap" method of filtration.

I am sure that some where there is some data comparing the "size" of the particles that get through both types of filter. Obviously you pay more for the item which provides better i.e. catches smaller particles of dust, the trouble is that as you reduce the size of the captured particles you have to increase the size of the filleting agent or your volume of air past through would reduce as well.

I think the real reason for oil baths filters falling out of favour is due the cost of building a oil bath system compared to building a paper filter system. The amount of mechanical surround, metal or plastic is reduced in a paper filter system. The amount of time spent on maintenance is reduced on a paper filter system, take old one out, throw away, put new one in....

Having both gives you the best of both systems!

John

[Tennmogger]

Hi John, Garry,

We are in agreement on most of the points. No doubt there would be no reason for the paper filter after the oil bath if the oil bath were perfect. But, I still suspect the Haflinger paper filter is 'special' with better filtration than most paper filters. In conjunction with the oil bath, and the cyclone on mil Hafis, a very good system. The red dirt of Australia seems to be responsible for such a thorough filtration system (second only to Tennessee red dirt!!).

As for oil bath compared to an off-the-shelf paper filter (especially the "high flow" type, K&N comes to mind) the oil bath is still right up there in efficiency, and still my personal preference. I think the switchover to paper was for simplicity of service, not filtration efficiency. Ease of use probably takes priority over efficiency. 99.999% of the cars on the road never have to contend with agricultural field dust or the Aus red stuff!

Bob

[Julian B]

Don't forget that the early Haflingers didn't have a paper filter element at all !

[Westernair]

Don't forget that the early Haflingers didn't have a paper filter element at all !

How early? My early 61 has both. What does the tube from the oil bath to the CARB look like?
On that note I am looking a intake pipe that connects to the oil filter. Anyone have an extra?

[Julian B]

This page (1-35) is from a June 1960 Parts Manual. When I bought my 1962 Haflinger it had a similar tube between the oil bath & carb, and always thought that it was original - but perhaps not if yours doesn't?

Julian

PS I have also attached a photo of what my engine looked like when I got it. Not totally sure if it was an original item, or something taken from a Fiat 500 / invalid carriage. I have since swapped the section out and installed a tube with a paper element in it. Belt 'n braces etc!

[heinkeljb]

Bob,

I don't profess to claim that the following filter is a "direct" replacement for the original sort other than the fact it is available here in the UK and it fits the original filter housing with no modifications.

FRAM CA641PL

First result from a google.co.uk search:-
http://www.autopartoo.com/oem/fram/CA641PL.html

Gives dimensions of the filter.

John