Re: full flow oil filter

Posted by su8overdrive On 2016/10/11 16:18:59

Fred Kanter and the other long experienced souls above give good advice. Fred and Dan Kanter were both Lehigh University engineering majors, as was James Ward Packard, where the first Packard is still on exhibit, so all the more know what they're talking about, having been involved with these cars before many of these forums' visitors had graduated to tricycles.

But the above question prompts me to post again the below, for what it's worth, as few here gathered bother to do a simple search on a topic before posting their questions.

Most Packards, if they have an oil filter, have a bypass, other than the aforementioned 1934-39 senior eights and 1935-39 Twelve, a rarity shared with the 1933-on Pierce-Arrows, which introduced hydraulic valve lifters, and 1931-33 Auburn Twelve ( the latter probably the best buy in the history of the car biz for a number of off topic reasons for those able to see past their own hood ornaments). So i thought the below interesting:

Expanding a bit on the above discussion of bypass vs. full flow filtration, here's an interesting letter in the 2006, No.5 Auburn-Cord-Duesenberg Newsletter by Al Light, Williamsport, PA, which is, coincidentally, where Lycoming, builder of all A-C-D engines, is still based:

"I really enjoyed the editor's comments on the club website about the real value of having an oil filter.

In the early 1950s while at Ford Engineering I was fortunate to hear an argument of "Full Flow" vs. "Partial Flow" oil filtration. The pro "Full Flow" people seemed to be more interested in the positive sales pitch that this system provided while the "Partial Flow" people seemed to
have a more solid engineering approach. The chief engineer from Fram Corporation stated the big difference was the allowable filter pressure drop. The larger the pressure drop, the finer and more material will be caught. With the full flow system you are restricted to approximately 10 pounds per inch drop across the element, and also require a bypass valve that will open when this pressure drop is exceeded. This of course is to protect the engine from oil starvation in the event of a plugged filter. With the partial flow, or sometimes called bypass system, the pressure drop is full engine oil pressure since
the oil discharges from the filter directly into the oil pan and not under any pressure. The system is automatically
bypassed if the filter plugs. It was also noted that a denser filter element is used on the partial flow system.

The Fram engineer summed up his thought by stating the answer to the argument was obtained by considering the following question: "Is it better to filter all of the dirt from part of the oil or to filter part of the dirt from all of the oil?"

He also stated that with the full flow system the bypass valve may open under cold starts and sometimes opens at high engine RPM when the allowable pressure drop may be exceeded. This results in no filtration under these conditions. His other comment was that the biggest advantage to full flow was to catch the machining chips, etc. in new engines. Fram's final approach was to propose the use of a combination system that did both full and partial filtering. I'm sure that this would have increased their filter business. I am not aware of any such system ever being used."


I can only add that an auld aircraft/auto mechanic/machinist/pilot and blown '37 Cord 812-owning friend said they were taught in tech school that a bypass filter will eventually filter all your engine's oil after a drive of 50 or so miles.

Another friend with '59 and '63 Ferraris showed me they left Modena with both full and bypass filters, as do some more recent trucks and heavy equipment, some of the latter coming only with bypass filtration.
Such equipment is likely to run hour after hour, shift after shift, so all the oil would easily be filtered.

As we've observed, for all the technological breakthroughs since Packard folded, much engineering is cost engineering,
but i don't know if this is strictly the case regarding bypass vs. full flow oil filtration with internal combustion engines.

Perhaps the above will be of some solace to those of us with Packards with the usual bypass filters. I leave further discussion to others, but would especially like to hear from engineers like Al Light, above, and members of the SAE. Meanwhile, if you want to do your engine a favor, ensure that the incoming air is clean and unobstructed, i.c. engines essentially air pumps and free breathing the key to power, life, economy.

Finally, never, ever start the engine unless you're going to drive the car at least 17-20 miles on the highway to prevent the formation of sludge, varnish, carbonic acid, the latter strong enough to etch concrete so you can imagine what it does to your bearings and rings. If you want to wash, wax, or work on your car outside, push it out the garage.

We still shake our heads at the alleged car buffs who start their engine and run it for a few minutes to show it off in the garage, then switch off the ignition and let the car sit for a month or two or longer.