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oiling + Oil Filtration
1999-2004
Part III of III
This gets complicated before it gets simpler. This has been a real education for me. We will demonstrate that unfiltered oil re-circulates, sometimes many times over, through the engine belying the claim that no debris can be transferred from engine compartment to engine compartment. The three Twin Cam compartments are; timing chest, bottom end and the top end. In comparison the Evo had two compartments: the top end and bottom end.
We are going to answer 3 questions:
1. Does a Twin Cam 10-micron oil filter work better than a 30 micron Evo oil filter?
2. Do Evo and Twin Cam oil filters, filtrate out ALL particulate more than 30 and 10 microns respectively?
3. Thirdly and most importantly does all the oil go through the filter?
Now that we have looked at (in Parts I and II) where and how the oil is channelled in the Twin Cam engine we can now examine oil filtration as well as the movement of debris throughout the engine with normal wear as well as catastrophic breakdown in this last of 3 parts. Harley Davidson like many other manufacturers have started to inform the consumer about the improved filtering capacities of their oil filters. They do this on a superficial level, which is all most consumers want to know anyway, by indicating the micron ratings for the filters. Harley does not make its own filters or oil but vendors them out for the best all round bid subject to their specifications.
Micron Ratings
For an easy but inaccurate consumer understanding of a filter’s capabilities, a micron rating is sometimes given by individual companies like Harley to show the efficiency of their product.
A micron is a millionth of a meter or for those not metrically inclined 39 millionths of an inch. The micron rating leads the consumer to mistakenly surmise that any and all particulate above the micron size rating is filtered out of the oil. The rating given to the Evo filter is 30 microns and the Twin Cam is 10 microns. Therefore the consumer, myself included before writing this article, makes some simplistic feel-good misassumptions regarding engine protection and oil cleanliness. Manufacturers do their own micron rating tests. There is no industry standard to do this by so comparisons between manufacturers are tenuous at best. However, as we will see, this is not a biggie because the micron rating doesn’t impart as much information as it seems. According to Amsoil, which has a top reputation in my books, almost any filter can filter out some particulate as small as 1/10th of a micron. As we will continually see, micron ratings are not accurate. Filter manufacturers initially used micron ratings to evaluate the relating porosity of flat sheets of media used in making
Filter elements.
The purpose of showing the relative porosity of a sheet of filter media has been served well by the micron rating. However, the micron rating has been used as a measure of filtration efficiency, something for which it was not originally intended. Some of the reasons why a micron rating is totally inappropriate for this are
1. The test is not repeatable at different labs. Each manufacturer has its own test procedures. Although the test is a valid comparison of one filtering paper or media to another within a given facility, the micron rating cannot be reliably used to compare filters from different manufacturers. One manufacturer may give a filter material a micron rating of 10 while another may rate it 2 and a third may rate it 15.
2. There is no consistent relationship between micron ratings and actual filtration efficiency. The relative porosity of a sheet of filter media is only one of the factors, which determines the efficiency of a filter. How it is made as well as the types of contaminants to be encountered, are also very important. The entire filter needs to be tested, not just the paper.
3. The micron rating does not show what happens to a filter over time. The micron rating is a one-pass test done on a new sample of filter material when many tests are required to see how the filter stands up over time and usage.
The Best Measure of Filter Performance
The multi-pass test has developed from the on-going work of Dr. Ernest Fitch of Oklahoma State University. This is a means of evaluating filter efficiency and answers the major deficiencies found with micron ratings:
1. The multi-pass test is repeatable. Therefore, multi-pass test data is comparable from one filter manufacturer to another.
2. The multi-pass test provides a true indication of filter efficiency because an entire filter is tested, not just a sheet of filter media.
4. The test does determine what happens to a filter over time because measurements are taken at multiple intervals during the filter’s test life.
How the Multi-pass Test Works
First, there is a continuous injection of contaminant into the oiling system where the separation capability of the filter is monitored. The number of particles bigger than a given size in the oil before it passes or bypasses the filter is divided by the number of same size or greater particles after it has passed or bypassed the filter. More than one ratio may be given for an oil filter because particles of different sizes produce different wear characteristics. Although multi-pass data does lend itself to comparison of filters from different manufacturers, it is still necessary for the consumer to be very alert to various ways in which information can be presented. Unfortunately statistics can be manipulated to create a half-truth or a contrived impression that may not be accurate.
Traveling Debris
Harley Davidson asserts that any timing case component engine breakdown and related debris does not affect other parts of the engine as outlined in Service Bulletin M-1097 titled
“Cam Bearing Repair Kits”:
“After careful inspection, Harley Davidson has determined that complete engine disassembly is unnecessary. All contamination is confined to the cam department and the return oiling system.”
I opined that the fine metal particles transfer from the timing compartment of the engine through the pinion bearing that separates this compartment with the bottom end compartment. I felt this occurred via suspended particulate in the oilified mist that is transferred back and forth with violent pressure differentials caused by rapidly ascending and descending pistons. Then an AIM Techline reader Mike Goshert with extensive mechanical knowledge emailed that ” (your) explanation that metallic debris would not be circulated through the entire engine would only be accurate if all the oil passed through the oil filter! The filter has an internal bypass so element restriction does not reduce flow. It would probably scare us to death if we knew how little oil was filtered. Odds are that a metal particle could make a number of passes through the system before it was finally caught by the filter element.” Well, after a few minutes of contemplation, I realized that there are now two sources of impure oil traveling from the timing compartment throughout the motor. In fact, Mike’s comments take this even further in that debris created anywhere in the engine can travel most times unimpeded throughout the engine without being immediately and totally filtered. This is the primary reason that micron ratings lead to inaccurate assumptions. The question is not a specific size of particulate being filtered but how many within a size range? The bigger question is how many are left behind to cruise through the engine. Filter manufacturers who respond to industry needs and wants are not concerned about a micron rating since it lacks crucial information. What they are concerned about is how many, (expressed as a percentage); particles in the 5 to 20 micron range are removed. Why? These are the most damaging particle sizes to an engine. They relate to the tolerances between mating parts. The particulate must be small enough to get in where it can cause damage. Therefore this primary size-range of particulate becomes the enemy that a good quality filter must effectively deal with. The statistics that determine a filter’s effectiveness are ones that measure filter “efficiency” and “capacity”.Both efficiency and capacity are measured by an industry-standardized test, which is called SAE HS806. SAE stands for the Society of Automotive Engineers. This group has industry respect and designates and delineates many standards such as the oil viscosity rating on any oil you buy such as SAE 20W50.
Oil Filter Efficiency
Efficiency is how much particulate is stopped and stored by the filter in a any given range such as between 5 and 20 microns. Efficiency is expressed as a percentage of how many particles are removed from the oil within a specified range compared with the total amount of particles in the oil. Smaller particulate is also filtered but at a lower percentage rate. A good filter will also remove water that is produced by condensation within the engine. Obviously, larger particles are filtered also and stored but at a higher percentage rate than smaller ones. A quality filter not only extends engine longevity but also removes contaminants that reduce oil life. Therefore a good filter also extends oil quality. Filtering must be done without sacrificing oil flow, which is where by-passing comes in. We will be discussing this a little later. Fineness and uniformity of the filtering material determines filtering efficiency of a specified material. If it is superior the material used will allow more oil flow through it than other substances. Most good oil filters on the market have 90% to 98% efficiency ratings in the 40-80-micron range. For example, Perform filters claim this 90-98% rating in the 28 to 35-micron range with nominal ratings in the 10-22 micron range. They also say that their filters have 4-micron efficiencies of up to 20% per pass through the filter. This is for oil that is actually filtered and not by-passed away back into the engine.
Capacity
Capacity is also extremely important. Capacity is how much filtered particulate that the filter can hold without blocking or impeding oil flow.Impeding oil flow is measured by the difference in oil pressure on the inlet side of the oil filter compared with the oil pressure going out the outlet and into the Twin Cam engine. Filter capacity is largely dependent on filter surface area. Modern filters are pleated back and forth. The size of filter and/or the tightness of the pleating determine filter capacity. Materials range from paper-like material as in the Evos to cellulose, fibreglass and synthetic media used in the Twin Cam filters. Paper does not remove as small a particulate as say synthetic media, which the 10-micron Twin Cam filters employ.
Magnets
Magnets placed on drain plugs etc. help greatly with the ferrous, (steel/iron) materials suspended in the oil but obviously won't catch the aluminium, plastic, and brass that could be circulating in the system. Non-metallic materials like plastic are not as destructive as metal particulate to the rest of the lubricated parts, but could certainly block small oil passages. Filters are only designed to remove by-products of the combustion process plus normal wear particles, which ultimately contaminate the crankcase. They were never designed to catch the overwhelming remains of major component breakdown such as occurred in some early Twin Cam timing case failures. While the 30-micron filter seems less efficient, it will filter more oil through its filtering paper before the bypass valve becomes activated. Changing filters is very important. As capacity to store contaminants is used up so is filtering material. In an extreme case, the filter’s capacity might be used up causing oil to back up thereby opening the by-pass valve on a full-time basis with no oil being filtered whatsoever. Pity the engine if the capacity is used up and the by-pass mal-functions in a closed position.
Bench Testing 5 Oil Filters
Mike Goshert, my email buddy, took the time to test 5 filters for bypass spring tension and to measure the area of the filter elements.His obvious expertise helped him devise a test bench for the by-pass spring pressures. He ended up using some PVC end caps, rubber gaskets, an arbor press, and a cylinder leakage tester to get the information about these pressure relief valves. The relief valve is necessary to keep the filter from collapsing when the flow through the engine exceeds filter flow. It would be nice if this only happened when the filter was not changed often enough, but it would appear that it is all too common an occurrence due to fine micron ratings and high viscosity oil. The fine synthetic media used in the 10 micron Twin Cam oil filter can only let so much oil through it. The 20W50 oil when warm effectively becomes 50-weight oil, which is very heavy especially when compared to 10W30 automotive oil. So, we have relatively heavy oil trying to permeate an extremely fine media filter material. When there is a backup of oil, which causes pressure, the by-pass valve will open allowing unfiltered oil unfettered access back into the engine until the pressure subsides allowing more oil to be filtered. This pressure point may be at say 12 pounds per square inch or psi. This is compounded in cold weather or when first starting your bike because the oil won’t flow as well until hot. For the thinking reader it may now become apparent that a 30 micron Evo filter may filter more oil because its filtering material is not as fine as the Twin Cam one. Theoretically, the 10-micron filter would be more efficient but only if the oil went through the media as opposed to being bypassed back into the engine unfiltered by the by-pass valve.Following is the breakdown on popular well-known filters that fell victim to Mike’s curiosity. Each measurement is very important. By-pass pressure tells when unfiltered oil will be diverted back into the engine while filter area has everything to with efficiency and capacity.
Filter Part # Bypass valve Filter area
K&N KN-171C
14psi
164sq.in.(73"x2.25")
Fram PH6022
12psi.
101sq.in.(45"x2.25")
Amsoil SMF134C
12psi.
106sq.in.(47"x2.25")
A/C Delco PF53
10psi.
96sq.in.(55"x1.75")
H-D 63731-99
10psi.
63sq.in.(36”x1.75”)
The A/C Delco filter internals were interesting since all except the element were identical to the HD filter, which would suggest they have a common manufacturer. The tests indicated that the H-D filter had only 27% of the capacity of the K&N filter tested. Logic would seem to dictate that more oil could pass though more surface area of filter. If using an automotive filter on your Harley, it is crucial to ensure the by-pass spring tension. For example if the by-pass pressure is rated at say, 28psi, then oil would back up until it exerted 28 psi on the spring. This wouldn’t happen in a Harley because the oil pressure rarely exceeds 15psi. Therefore oil would backup and starve the engine for lubrication. However an automotive filter with the correct by-pass tension may have greater efficiency and capacity because of possible increased filter area.Mike’s parting words are that of a gentleman and a good guy; “I hope this info saves an engine or two for your AIM readers”.
Filter By-Passes
The only application we could come up with that actually filtered all the oil pumped was a system on an old Ferrari. It had a bank of three very large filters. This is not practical because of space considerations on a motorcycle. The funny part was that this particular car was being repaired for low oil pressure due to filter restriction. In my opinion filters have to have a functioning by-pass system. Perhaps a multi-by-pass strategy would work on a bike like the Twin Cam. Filters are designed to remove a percentage of parts wear particulate every pass through the oiling-filtration system. They are not designed to cope with total or catastrophic engine failure. Suppose the filter was designed for more efficient filtering as well as with component failure in mind. Normal by-passed oil away from the 10-micron filter could be channelled through a second less strenuous filter like say a 30 or 40-micron element. Mike suggests moving the by-pass to the other end of the assembly and adding a 30-micron element down the centre of the tube, which would help our area of concern. Another by-pass spring would have to be located there in case oil backed up. Amsoil sells excellent multi-pass filters but they are bulky.
The Bottom Line
I believe that debris laden oil transfers between Twin Cam engine compartments. This occurs while suspended in the gaseous mixture forced back and forth through the pinion bearing by the windage created by the ascending and descending pistons throughout all three compartments of the Twin Cam engine or through by-passing the 10 micron media in the oil filter. I am convinced that unfiltered oil re-circulates, sometimes many times over, through the engine belying the claim that no debris can be transferred from compartment to compartment.
Reading The Filter
A really neat way to diagnose and to see what is going on inside your engine is to read the filter element. We do this all the time for customers at Heavy Duty Cycles. They think we are magicians until we show them how we knew certain information. Take the used oil filter, cut the metal away and extended the paper or fibrous cloth as the case may be. Put the material up against the sun or a bright light and any damage will be there for all to see. If there are fine metal specks have a trusted mechanic examine the cloth or paper and make an evaluation. Shiny metal indicates hardened metal like that found in bearings while dull grey would indicate aluminium and that there is piston wear. Gold or brass specks are from bushings. Melted or dull orange-brown deposits would lead the thinking mechanic to examine wear on Twin Cam timing chain adjustor shoes. And on it goes. A simple examination gives a wealth of information on the health of engine internals.
Cleaning and Inspecting the Oil Pan (Tank)
Oil tank debris on magnetic drain plug will pick up steel but not brass or aluminium but it is a great indicator of what may be going on.Always inspect drained oil under intense light to see how much particulate is floating around. Sediment that gravitates to the bottom of the pan is also a great indicator. If a lot of metal is found on the primary drain plug magnet it is not as serious as if found elsewhere. The primary chain and its sprockets produce lots of filings especially if not properly aligned. The chain will begin to cut a new path, leaving major shavings to be collected by the beleaguered magnet. Again, evaluating what and why gives a wealth of information.
Warranty
Using quality brand name filters does not void vehicle warranty. Some dealer service representatives falsely claim brand name filters “void the vehicle warranty” if used instead of vehicle manufacturer brand filters during the warranty period. They say the same things about oil. This is not true. Under the Magnuson-Moss Warranty Improvement Act, a vehicle manufacturer may not make its vehicle warranty conditional on the use of any brand of filter or oil unless the manufacturer provides the filter and/or oil free of charge.
Conclusion
Finer filtration combined with relatively thick, (viscous), 20W50 oil makes it necessary for a multi-pass strategy. This is required in order to prevent oil from backing up behind the10-micron Twin Cam filter and starving the engine. Because of this it is also plausible that more oil will be filtered in a Twin Cam each pass with a less restrictive filter such as the Evo 30 micron. Therefore an argument can be made that a less restrictive filter may in fact filter more particulate each pass through the engine oiling system. More oil will go through the filter material before backup occurs and the bypass valve opens to divert unfiltered oil back through the engine. Again, I quote a Factory Service Bulletin regarding the transfer of debris throughout the engine; “After careful inspection, Harley Davidson has determined that complete engine disassembly is unnecessary. All contamination is confined to the cam department and the return oiling system.” In any by-pass filtration system used on all modern vehicles including the Twin Cam Harley Davidson a portion of the oil will be filtered efficiently before it re-enters the engine. However on each pass of oil through the filter, another unfiltered portion will be bypassed away from filtration and back into the engine carrying suspended particulate and debris. This may happen many times. The only conclusion I can draw from this is that damage and debris cannot be contained in any one of the three Twin Cam compartments. Not only are worn metal shavings carried back into and around the engine via normal circulation, I feel that suspended fine metal particles transfer from the timing compartment of the engine through the pinion bearing that separates this compartment with the bottom end compartment. I feel this occurs via suspended particulate in the oilified mist that is transferred back and forth with violent pressure differentials caused by rapidly ascending and descending pistons. Furthermore, it is much easier to transfer particulate up into the top end compartment when the pistons descend forcing the gaseous mist up the pushrod tunnels into the top of the heads. For me, if there is catastrophic damage anywhere in any Harley engine since 1903, then the whole engine must be disassmbled for at least a thorough cleaning and possible rebuild. Oil filtration has never been more efficient than on modern Harley Davidson’s but as we can see from our discussions total and complete filtration with each pass through the engine is not happening. This is information that is left unsaid. The way discussions of filtering are worded leads to the misassumption that all oil is filtered continuously.
Donny Petersen
Heavy Duty Cycles Toronto
www.heavydutycycles.com
