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Author Topic: This is What a Ruined 8V71TA Looks Like...........  (Read 8855 times)
thomasinnv
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« Reply #15 on: August 04, 2011, 09:32:18 PM »

BTW, you don't even want to know what I found sitting in the bottom of the airbox. SCARY.

  Yeah we do.

Yeah, you know as soon as I posted that, I thought "now that was stupid. Just hang it out there, dummy"

So here it is. When I removed the blower, I found sitting right in the middle of the bottom of the airbox a small piece of metal, maybe about 1/4 x 3/8 inch in size. One of the liners had a piece missing from in between the ports that seemed about the right size and configuration. The piston in that hole had no sign of trouble though, and there was no sign of trauma anywhere else that I could see either. Judging from the dirty oil on the airbox, that piece had sat there for quite some time without moving. No telling how long it's been in there. Bus just blows a puff of smoke when cold, nothing out of the ordinary.
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There are three kinds of people in this world....those that make things happen, those that watch things happen, and those that just wonder what the heck is happening. Which one are you?

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« Reply #16 on: August 04, 2011, 09:33:25 PM »

To my understanding, the oil bath filters are efficient for both air flow and filtration at increased rpm, but do not filter as well at idle.
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« Reply #17 on: August 04, 2011, 09:48:33 PM »

I don't know Lin the DD literature I have shows the oil bath flow 6% less than paper and the oil bath is 95.3 % on filtration and the paper spec for DD are at 99.8 on filtration that is what I go buy

good luck
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« Reply #18 on: August 04, 2011, 10:45:54 PM »

No telling how long it's been in there. Bus just blows a puff of smoke when cold, nothing out of the ordinary.

  Some would freak out and want a complete teardown, solve the riddle...

  After watching a few Bus engine out of town repair tales here, I concluded that I would make whatever effort I could to make it run and get as close to home as I could. I cant say I wouldnt want to know precisely where that chunk of metal came from, and a chunk from the liner would concern me, but if its chugging along and hasnt been protesting, who's to argue??  Just realise that it could lead to catostrophic and sudden failure, if you not entirely sure of the extent of damage or the cause.

  What I have learned is that these engines are amazingly tough, and rather simple, albeit heavy. Even in the case of a complete cylinder failure, or dropped valve, its quite possible to Jerry Rig things enough to keep it thumpin down the road a ways. A blown bearing in the blower throwing chunks into the motor however, thats kind of a deal breaker.
 
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« Reply #19 on: August 04, 2011, 10:59:50 PM »

I have a Donaldson air cleaner with 7" hose (up from 6" before turboing).  After replacing the original air filter I put in a Baldwin "replacement" filter.  It looked the same, but the foam gaskets were thicker, so it was almost impossible to button back up.  It didn't last but a year, and just replaced it again with a Donaldson genuine replacement filter element.  It fits perfectly and the air flows well again (no smoke on hard acceleration).  Use the name brand air filter your air cleaner is made by for guaranteed fit.

Also-do not EVER blow out a paper air filter element and reuse it.  The air will create micro holes in the element and let dirt in.  Considering the air filter element is around $100.00 and you probably replace once every 2-4 years, how cheap is that?  Always replace a dirty paper air filter element when it is ready-helpful to have a vacuum flow gauge that shows red when ready on the air filter can.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #20 on: August 04, 2011, 11:25:35 PM »

   I pulled this off wikipedia, kind of interesting and explains why they are still used.

  "Oil bath air cleaners were very widely used in automotive and small engine applications until the widespread industry adoption of the paper filter in the early 1960s. Such cleaners are still used in off-road equipment where very high levels of dust are encountered, for oil bath air cleaners can sequester a great deal of dirt relative to their overall size without loss of filtration efficiency or airflow. However, the liquid oil makes cleaning and servicing such air cleaners messy and inconvenient, they must be relatively large to avoid excessive restriction at high airflow rates, and they tend to increase exhaust emissions of unburned hydrocarbons due to oil aspiration when used on spark-ignition engines".
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« Reply #21 on: August 05, 2011, 05:38:47 AM »

Just for shiggles what is the average life of a paper filter on an Eagle, or better yet a 6v92?  I know all conditions change the game but what is the regular scheduled time for changing>
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« Reply #22 on: August 05, 2011, 06:00:29 AM »

You're supposed to use a manometer to measure the flow resistance to tell you when to change.  Could be a week to 10 years...

Brian
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Ed Hackenbruch
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« Reply #23 on: August 05, 2011, 07:55:22 AM »

I can't think of a single piece of heavy equipment that still uses an oil bath cleaner.....haven't seen one in years, in fact i can't recall that last time that i did see one. Grin
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« Reply #24 on: August 05, 2011, 07:58:16 AM »

I see four of them sitting on the ground beside my bus every time I walk out to the shop!   Grin  Dang things are heavy too - I bet the complete stock air cleaner setup on my bus weighs north of 150 lbs.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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« Reply #25 on: August 05, 2011, 08:02:54 AM »

You never see oil baths on equipment any longer and haven't in a long long time they all have turbo engines a oil bath is a no/no for turbo engines,Cat hasn't used a oil bath filter since early the 60's fwiw
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« Reply #26 on: August 05, 2011, 12:50:26 PM »

   I pulled this off wikipedia, kind of interesting and explains why they are still used.

  "Oil bath air cleaners were very widely used in automotive and small engine applications until the widespread industry adoption of the paper filter in the early 1960s. Such cleaners are still used in off-road equipment where very high levels of dust are encountered, for oil bath air cleaners can sequester a great deal of dirt relative to their overall size without loss of filtration efficiency or airflow. However, the liquid oil makes cleaning and servicing such air cleaners messy and inconvenient, they must be relatively large to avoid excessive restriction at high airflow rates, and they tend to increase exhaust emissions of unburned hydrocarbons due to oil aspiration when used on spark-ignition engines".

Don't ya love it when Aldous Huxley proves to be correct one more time?  "Send me a man who reads".

Look, I might be missing something, Lord knows that happens often enuf, but, the oil bath keeps coming up the winner every which way I turn this comparison.

Pro:

The OB is cheaper in the long run if filter elements cost a hundred bucks.

     The oil bath has no replacement materials except the oil being replaced.  Any light weight oil will do....used 20wt or ATF...doesn't matter.  Motor Earl is motor Earl in this case.  Filters cost 100 to 125 dollars per change.  How many changes do you have to make before you hit the break even point of a OB?  After that it is all savings.  And those savings don't end.

Fuel savings will be significant over the life of the engine.

     The dry filter element traps the dirt "in series" with the air flow.  That is to say that the air charge must travel "past" the dirt to get into the engine.  All those tiny air passages in the element get filled by dirt as time goes on.  That's how the filter works.  With the filling of those holes come resistance to flow and that adds up to loss of fuel efficiency.  The OB stores the dirt it traps in the bottom of the oil bath reservoir where the charge air never goes.  Instead, the air going into the engine "slides" over that "slick" oil surface on its way....  (little humor there).  The OB works just like the day it was borne even when it is half full of muck and dirt and twigs and talc.  You keep the oil level where it should be and it works like nothing has happened even after years of deferred maint abuse.  Obviously the thing can't work after the dirt gets to the oil fill line but till then all is hunky dory.

OB has more air resistance to air flow than a dry element.

I'll bet that the brand and expense of that element has a lot to do with that number.  Still, even without numbers, I would say that that must be true.  Here's the rub.  Like I said, the resistance to air flow is going up from the time it is put into use, regarding the dry element.  That should be obviously true to everyone.  The resistance number for the OB must be a point that the dry element passes on it way to needing replaced.  My unsupported argument is that the losses associated with the OB being less efficient at the outset are overcome by the excessive losses of the DE during its final phase of use.

Remember all the discussion about bends and length of run associated with intake air flow resistance?  Who could forget?  Well, that OB has a 180 degree turn in the air flow path built into it as a operating principle.  That makes a lot of resistance but the DE is restrictive by its nature, as well.

OB is more labor intensive and costly than a DE


      The DE needs to be replaced on a "time run"  and "conditions" basis.  The OB needs "checked" on the same basis.  Actual servicing intervals are much much less frequent.  Operating in Southern California I got 1/8 inch of "clay" out of my OB filter after one year and 20K miles.  I didn't clean it again for 4 years but I checked it every 6 months....religiously.  Elements were only a few bucks back then.

CON:  The OB works on the centrifugal forces associated with an air stream abruptly changing direction.  The 180 degree direction change in the bottom of the filter "flings" the dirt particles "at" the surface of the oil, where it sticks and sinks.  Remaining air flow is "clean".  The finer and lighter the dirt particles the faster the air must be traveling to be thrown into the oil.  "Smoke" would not likely be trapped....also doesn't do much damage due to abrasion.   BUT there is a trade off:  the faster you make the air flow the better the filtering but the greater the air resistance and subsequent negative impact on economy.  The OB in autom otive use is a trade off.  To filter the air must travel fast and the design is to get acceptable filtering at the most used air velocity thru-put.  That would be cruise and the desine would be pecular to the engine displacement.  Move the RPM up to MAX and the OB is sucking harder and not as free flowing.  At idle the velocity of the air at the turn isn't great enuf to allow the best filtering.  Turns out, as my guess, there is more than one reason for DD being adament about not letting the engine "idle" for very long at all.  Air filtering, it seems, on those "olde timey" 2 strokes got poor at idle.  Sand and grit will not make the velocity turn regardless and less of that can be moved at idle but the talc is always there.

Here's the main point: They still make the oil bath filter.  There is a market for them.  I am told that all rock quarry equip is equipped with the OB filtration and that the rock crusher running at the bottom of the pit is most certainly OB equipped.  That comes from a D mechanic that worked in more than one quarry.  Farm equip, still comes with OB filters in some cases and here again....I been told.  My call to Caterpillar got me the following:  They are no longer standard equip on OTR truck engines.  Until recently they were an option. That rep said he knew that 3408 engines for trucks came with the option of a OB filter.  His "guess" was that heavy equip still used them but where DE filters used to be the option the OB was now the option.  Times change and not always for the better....mostly, but not always.

Today, the mfr gets a profit on DE replacement parts.  Not everyone sold but the dealers still install their house brands and, while they are made by suppliers, they are usually way more expensive.  They get not a nickel for OB after it leaves the factory.  True, they get more to service the OB but most service is not done at the dealer.  Lots of crossed motives and reasons of profit in this mix.

I would choose the OB if it were an option.  I would certainly install a "Filter Minder" on every DE equipped engine....as I have done. And I would change no filter before it's time nor run it beyond it time.

John

 


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« Reply #27 on: August 05, 2011, 01:08:47 PM »

Come on Ed,, confess,, you've allways wanted to be an instructor haven't you??>>>D
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Utahclaimjumper 
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« Reply #28 on: August 05, 2011, 01:16:02 PM »

  I cant say I would choose an OB filter over a paper element, but I sure aint gonna tear it all out just to start buying paper elements.

  Regardless of things stated, I believe the move away from OB air cleaners had more to do with convienence and parts sales than anything particularly scientific, as well as a move away from something seen as antiquated. Its interesting that DD, who until the 1990's was owned by GM, would claim the paper element was a better and higher flow filter over an OB filter. Yet every Bus GM built, from the 1930's all the way into the 1980's, had OB air filters rather than paper elements.

  They arent bad filters, just messy. And they are much better than either a dirty paper filter, or a high flow filter like K&N.
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« Reply #29 on: August 05, 2011, 01:27:20 PM »

If you want to pay shipping and packing, I'll send you the oil bath filter from my MCI gratis...  it has four elements, weighs around 150 lbs and is a lump roughly 16" tall by 20" wide and 24" long... Wink
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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