Here from DD then you make up your mind which is best for you and we can put it to sleep
Air Cleaner Characteristics
Dry Type Oil Bath
99.8 to 99.9 % effective regardless of 96.to 98.7 effective depending on
engine speed (see Figure 7) engine speed (see figure 7)
Less restriction to air flow Greater restriction to air flow
Performance not affected by Performance may be adversely
temperature affected by temperature extremes
Compatible for use with turbocharger Not recommended for use with
turbocharger due to oil mist
May be mounted at any angle Must be mounted vertically
Engine performance will indicate if Engine performance will not
if element replacement is overdue indicate cleaner is preforming
properly
No danger of engine runaway due to Possibility of oil pull over
due to oil pull over
Use of restriction indicator is acceptable Use of restriction indicator not
acceptable
Oil vapor from crankcase ventilator Compatible with crankcase
may clog element ventilator
This is from Detroit sorry I cannot do the the figure 7 chart Dave can do that when he shows
Sure, when you put it that way it looks like dry filter is a better candidate (sorry, the election is creeping in everywhere), but you can't spill a paper filter. You just pull out the old one and put in a new one. Where's the challenge in that? They are called "oil bath filters" for a reason! Give me an oil bath, a Spicer, and a huge folding map spread over a 26" steering wheel (none of that new fangled power assist neither. Yeah, and if God meant for you to be cool in the summer, He would have made it more like winter. Air conditioning--Phooey!
I'm not believing 99.9 as a blanket statement. There are 25 major brands and styles of paper filters and some must be notably better or worse than others. Techno's paper filter didn't work out to good. I'm not saying they aren't better but not all filters are the same. I once saw a study were oil bath excelled vs paper at high rpm. I can't find it now and don't remember the exact results and even the validity of the study but I wouldn't blanket statement say paper is better. Type, brand, cfm rating, proper installation and duration of use would all factor into it for me.
Quote from: Scott Crosby on November 05, 2016, 11:37:05 AM
I'm not believing 99.9 as a blanket statement. There are 25 major brands and styles of paper filters and some must be notably better or worse than others. Techno's paper filter didn't work out to good. I'm not saying they aren't better but not all filters are the same. I once saw a study were oil bath excelled vs paper at high rpm. I can't find it now and don't remember the exact results and even the validity of the study but I wouldn't blanket statement say paper is better. Type, brand, cfm rating, proper installation and duration of use would all factor into it for me.
Take it up with Detroit not me they used Donaldson or Farr in their manuals and they tell you not to use a paper filter that is over 3 years old in the manual.I don't believe the filter was the cause of Techno's problem either or they could have collected that is why one buys good filters.
I am just passing on the info to the ones that have a question and are thinking about changing to paper what you or I think has no bearing on what people use
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.gmtruckcentral.com%2Fimages%2Fair-filter-study%2Fpercentage.jpg&hash=ff00637c08aa00ddae990d06fcd31fbdb4b334d0)
These aren't in a Bus engine but look at the wide range of results. I didn't read the whole study so here it is for research. Most buses I see that have paper it's almost always older than three years ;) But thd oil baths probably haven't been serviced in three years either on the oil bath ones
http://www.gmtruckcentral.com/articles/air-filter-study.html (http://www.gmtruckcentral.com/articles/air-filter-study.html)
You are right that is not a bus or truck filter 250 CFM on that test is not much.I have a ? why would you 3 or 4 oil bath filters when 1 dry filter can produce better results.I really thought DD gave the oil baths the benefit of doubt with the 97 to 98 % everyone else says 95% at tops
Quote from: luvrbus on November 05, 2016, 12:37:27 PMYou are right that is not a bus or truck filter 250 CFM on that test is not much. ...
Something I find surprising is that there's a filter that allows more contaminant to pass than K & N!
I do know from having a family that had lots of fields to plow when I was growing up, My Dad used to clean dump and change the oil in the filters 3 times in a 12 to 14 hour day on a dusty field because he said the oil bath would have so much dust and dirt in it that it actually would come to a point of skimming over and not stopping the dust from going around the center tube and right up into the engine. We had CAT's (Tractors) in those days with 2 oil baths each tractor. Point being if they get cleaned regularly the oil bath would work to a point but if not would pass dirt and dust into engine, where as a paper filter would stop it until it shuts off the air flow unless there was a hole in the filter material.
Dave5Cs
And I'm not arguing with you Clifford, I'm just having a discussion. I was just pointing out that To just say paper is better than oil bath is not true. Specific paper filters under specific conditions can be better than oil bath filters. And if it costs someone $400-$800 to have a paper canister retro fitted into their bus, the properly maintained oil bath system will work just fine if they can't afford it. I have paper in my 6v and I get way more dirt out of my oil bath filters. Yes the paper can have it suspended in the media and the oil adds to the consistency of the dirt in the baths but my eyes see how much dirt I remove even after a 5,000 mile trip from the oil baths and it's a lot that comes out. That paper filter should be black and not nearly white with the amount of dirt that comes out of just one air bath filter change. Some oil assperation happens in the intake, but it's clean in the tube not dirty or gritty. Even my lobes are clean as can be with my oil bath bus. The EPA complained about the oil assperation and I'm sure the disposal of the contaminated residue too. There is money to be made in replaceable filters too so motive could come to play on weighing that in. I also have a sheet from Detroit saying the recommended oil change interval in a 71 series is 100,000 miles. It don't mean I'm taking that info as the ultimate truth. Now a lot of this stuff is made in China or some other third world country and would I blindly trust the quality control of it? What's the failure rate of a paper filter? How often are they physically examined? Are they installed correctly? Could a rat chew a hole in one? Does water damage the paper? Probably a hundred reasons why they could fail. For old technology the oil baths can work really good, and in many cases better than paper, but I'll give you that many times paper can be better but not a blanket "better"
When I rebuilt the 4-71 in my Courier 96, it had a oil bath filter. Worked pretty good, as long as you service it regularly and keep it clean. When I was researching what to do about turboing that engine, I was asking different mechanics what to do about the oil bath. The young mechs were telling me get rid of it, it will suck oil into the intake. The old mechs were saying keep it, it will work with the turbo, and it won't suck oil. So I kept it just to see. Well it never sucked oil into the intake, and it worked really well. I put 20000 miles on that turboed engine and it did good. I had proved a point, mostly to myself.
I also have a 220 Cummins for a power unit on a saw mill that is turboed and still running the oil bath filter. It only sucked oil once when I overfilled it once about a 1/2" above the line. It revved up a bit and smoked for a few minutes until the excess oil was burned off. I had my hand ready on the fuel shut off just in case...
Probably the biggest reason they changed to paper filters is ease and speed of servicing, when labor became expensive.
Is paper better than oil bath, I don't know.
JC
In a different respect as in the 2 cycle Jimmys being taken out of production, so too for oil bath air cleaners due to EPA constraints. Read that in a couple articles. I would think a Jimmy would get pretty thirsty without some oil in its intake so I'll just keep letting it sip so it don't get thirsty. You know if politicians took a problem, any problem and talked it like we can well it would be some kind of world, wouldn't it? Probably would be more busses around too! :-)
That 100,000 mile oil changed was short lived you should have a bulletin replacing that page I have it 18SE30- release 83.
Engineering bulletin 39 still stands no revisions have been made to it or I would have received it.I really don't care what people use that is their business.
I will say most dry Donaldson filters have a Vaculator valve or tiny holes that shake the dirt and water out of the filter by using the impulse of the engine.
My Vaculator valve keeps my filter fairly clean even living here in the desert that valve is a engineering marvel by Donaldson.
I wish I had Jet Air cleaner like the military uses on Abrams tanks they get a lot of use out of paper filters.
Where did you get the $400 to $800 price ? I can replace those oil baths with a ECO system for $150.00.
I know from years of using a oilbath filter if you don't stay on top of it they will dust a engine ask Brian Evens of Canada here on the board
I just posted reference material documented by Detroit the people that made the engine people here can do what they choose to do with it but it here if they need it
A few years ago I modified the intake plenum above my filter to be easily removable so I can now see down inside the filter itself. My old filter had begun to split internally, probably from old age and maybe also from rain that weakened it, so I made sure I wouldn't have any more surprises in the future. I also made a rain catch tray inside the plenum to prevent the new filter getting wet. Anything you can do to make it easy to check the inside of the filter on a regular basis could prevent big problems - remember, a split filter won't show any restriction on the Filter Minder.
And just like batteries, look at the production date before you buy. I had Racor make my ECO-BC to order, so I know it wasn't sitting on a shelf for years getting brittle and weak.
John
A oil sample @10,000 miles will show the paper works better than a oil bath I found out years ago
I toyed with the idea of having both an oil bath and a paper filter on the same engine that was subject to a lot of dust and dirt, but with the air restriction of the oil bath and the oil vapor problem, it would not be practical. We ended up using a Donaldson model that had dual filter elements, one inside the other. That has worked well, but I don't think they have it for larger engines.
I worked on a bus this spring that the paper filter didn't do better. They had a filter minder gauge on it and it was in the green. I opened the housing and.... no filter. The owner said oh I forgot I put that in my other bus like two years ago and forgot to order a new one for this bus.... I suppose he could have removed an oil bath filter too or forgot to put oil in it because that kind of stupid is real stupid ;)
I started putting these turbo pre cleaners on dirt and gravel equipment way back because sometimes in a fleet way ya try to stay ahead and its tough sometimes.
http://www.turboprecleaner.com/ (http://www.turboprecleaner.com/)
I used the 1 and followed up when they introduced the II model, they help tremendously.
Its been (I don't know why) but will just say bean counting, even though I'm a stickler for measure up accountable, anyway in enough meetings and training the mention not to touch the dry air cleaners now, to say blow it out (as old days)because it introduces dirt? whatever.
The promoting in many instruction sessions is that the sensors and gauge sometimes in cab both mechanical and commonly now dash warnings for air restriction, kinda the new thing.
The inspection is a great thing for sure, measure up or get your lunch box and hit the road that's the way it was when I was hired, now its have some cookies ;D
I guess many things are making it not only easier as this air filtering but in ways providing a proof its ok and keep working, ah? don't know, anyway! ( do you remember the first time you got a message on the truck dash screen ) wha ??? :o ::)
My utility tractor outside still has oil type filter, even while sand blasting it 15 years ago to repaint I musta thought 100 times if only there was a decent fit for replacement.
It had crud just 2 days ago "before this post" and I wished the same again.
Something important and just mentioned by John, In old and especially many new aero type hoods on trucks sometimes filtering out wet and snow can be a real task, ya know this when they start freezing up and restricted if not fitted with diversion air from say engine area, big pita and cold way out in the boonies at 2am.
Floyd
Clifford has a good memory, the PO ran the engine in my bus with no oil in the filters for who knows how long, there was a half inch of dust sludge inside the air box when I looked inside. Done and dusted, I changed the engine.
Point of trivia I guess, oil bath air filters work by forcing the air through a 180 degree change in direction directly over the oil bath. The high velocity of that change in direction literally flings the dirt particles out of the air stream at the oil surface, which captures the dirt. The air then passes into a large volume of steel mesh that is damp with oil, and smaller particles stick to the oil on the mesh. The design works based on Bernoulli's principle, believe it or not. Small area of air passage towards the oil cup creates high velocity to effectively fling the air, then large volume of space with the steel mesh slows the air down so dust can be captured by the sticky oil. This is why there are typically three or four oil bath filters - they depend on the ratio of size for their operation, so they can only be so big for a given volume of air. To get the required air flow they put more filters in parallel.
One thing no one ever discusses is air flow restriction and it's effect on performance. A restrictive air intake system kills performance exactly the same as a restrictive exhaust. I don't have any data on this, but I would expect that the oil bath filters are far more restrictive than a big Donaldson.
Brian
I found this in bulletin 39 page 2 from Detroit
"Dry type air cleaners are the most efficient cleaners available for mobile equipment.They can separate up to 99.8 to 99.9% of the dust from the air at acceptable pressure looses.The efficiency of dry type air cleaners remains constant over a range of engine speeds."
When I was on a management team that took over a transit fleet, we found that previous (parsimonious) management had instructed maintenance to blow out the paper filters, not replace them. Fleet of 100 Fishbowls. I think the older group (45) had oil bath, I do know the newer (55) had paper. We lost a lot of engines -- and our machine shop was painfully slow at overhauling.
Same property, previous management. The Maintenance Department had used it's budgeted allotment of Freon (5 tanks for 100 buses in a mid-Atlantic state), so the crafty Maintenance Manager submitted a purchase order for chlorodifluoromethane, which was approved. Unfortunately, the invoice came in marked "Freon", so he got in trouble.
Arthur
All you have to do is look at the giant mining trucks and that they have multiple dry air cleaners. When I turbo'd my 8V-71, I changed the air cleaner from a 6" to 7" intake and supply. The case was the same, but the element is conical. To add supply, I added another air intake. Dry air filter elements are relatively cheap. Do not blow out elements-the air pressure can create micro holes in the element allowing dirt in-just buy a new element. I like Donaldson. Good Luck, TomC
Question on the restriction mentioned about oil bath cleaners. Would the restriction have as much a negative effect/performance deficit on a super charged engine as on a non supercharged engine?
Restriction always has the same effect. It's a resistance to the flow of air, and it varies with velocity and volume of air. With a supercharger or a turbocharger a designer can overcome the initial effects of resistance, and make it so they can be effectively ignored, by doing things like waste-gates - which allow a booster to produce a certain level of boost, and any excess is thrown away.
In the case of a two-stroke DD engine, the boost is mechanically fixed and there is no over-boost reduction, so any resistance will have an effect. The blower grabs chunks of air and forces them into the air box, the blower grabs more air than would be there normally, and so there is a pressure buildup inside the air box, and the cylinders are pressurized. If there is an intake restriction the effect would be that air pressure at the inlet of the blower is reduced below atmospheric, so the chunks of air the blower grabs are smaller and the pressure inside the air box is less. The engine is getting somewhat less air than it might otherwise, so less power can be produced. If nothing else is changed and the restriction is great enough, you might get black smoke or need to reduce the size of the injectors. This is exactly the same effect as you see if you drive your engine at a high altitude - the pressure at the inlet of the blower is lower, the chunks of air are smaller, the performance is less. Is this going to happen with the oil bath air filter on your 1950's bus? Almost certainly not, because the bus engine was designed as a system with that exact air filter in mind. Would reducing restriction help performance and economy? Absolutely yes, but to what degree I have no idea. I just know from decades of experience building race engines that it will help.
Oil bath air filters are, in my humble opinion, fine. They are state of the 1930's art. They are serviceable in the field, they can be designed to match the engine in terms of flow, they aren't bad. A three or four chamber oil bath air filter setup, exactly what I had in my bus, if I was to try to buy a new one today would cost between $1,000 and $2,000. It was over 100 lbs of intricate stamped steel, lots of fabrication, captive nuts, bolts, clips, it was complicated. I replaced it with a $100 Donaldson that weighs 15 lbs, is 1/4 the size and has 2015 state of the art filtration.