oil bath filter design

[naildriver]

I have read two different things. One says that dust is pulled down where at the last portion, the air makes a quick 180 degree turn up and the dust because of momentum gets caught in the oil which is just below the turn.. Another says that oil is sucked up into the mesh where it grabs particles. The first one would seem to not have as much restriction as the second. Also, the first should not get progressivly worse as far as air flow. So, Which is it? I have also heard the the oil bath was superior when it comes to fine dust. I think a cone on top with the first example would be a good combination.

[pjjms]

I have not measured the filter on my Dexta but have on the Nuffield. The vertical pipe from the mushroom exits below the oil level. I assume the air bubbles through the oil and the mesh is there to stop oil making its way into the engine and does a good job of that. This also explains why an inch of dirt in the bottom raising the oil level has no effect on engine running.
I also note that when test running after restoring I had no oil in the filter, and this made the engine run very lean, to the extent that it was a bit of a pig to keep going when cold. It was bad enough for me to give up test running after just a few minutes followed by some head scratching before I tried it with the filter oiled.

Peter

[Kiwi Kev]

We need to remember that every bit of air that goes through the air cleaner, wether it be an oil bath, paper filter or what ever, goes into the cylinder and head. Any air particles within the air can cause damage to the bore and or valves etc.
Therfore we need to make sure that the air is as CLEAN as possible.
I recently cleaned out my oil bath filter, and was amazed at the amount of dirt in the bottom of the bath.
Kiwi Kev

[JC]

They work like your first example. The dirt falls out at the bottom of the 180 turn and gets trapped in the oil. Since the velocity of the air and the momentum of the dirt are what makes them work, they filter best at high RPM and with coarser particles. If you run low RPMs in fine dust, you will get a lot of dirt in your engine.

[naildriver]

I am considering some sort of prefilter. Yet I don't want to cause any restriction. Something visible, right there in front of me that I can see, take it off, beat it on the finder, pop it back on and keep plowing. Anything caught in the pre filter is that much that you don't have to clean out of the oil bath. What are your thoughts????

[The Swanndri Guy]

Naildriver, you could consider a Donaldson precleaner on the air intake to the oil bath air filter, as used on the 1000 series Fords.There is a Super Dexta down the road and that is exactly what they have done. TSG

[JC]

Excellent idea. It won't restrict the airflow, you can see when its got dirt in it, and its easy to clean. Don't beat it on the fender, though. You'll break it

[naildriver]

Hey, many thanks. That full view precleaner from Donaldson is EXACTLY what I had in mind.

[Blue Swede]

I have read two different things. One says that dust is pulled down where at the last portion, the air makes a quick 180 degree turn up and the dust because of momentum gets caught in the oil which is just below the turn.. Another says that oil is sucked up into the mesh where it grabs particles. The first one would seem to not have as much restriction as the second. Also, the first should not get progressivly worse as far as air flow. So, Which is it?...

It is a combination of the two: http://www.tpub.com/engine3/en32-4.htm