Packard Forum Index » Post-War (1946-54)

Hey guys,

One of the things I don't understand about my car is how the oil filter works. There's a solid metal rod that holds the filter cartridge in the oil filter housing, at the top is a threaded hole which allows the cover bolt to hold it down. There's also a small tube on the side, which carries oil. Now, my question is, how exactly does a cartridge filter work if there is only one tube for the oil to (presumably) enter the filter and then exit it? My understanding is that the oil needs to pass thru the filter (presumably from an open tube in the middle) and then the clean oil passes thru the filter medium, and then (presumably) out the little tube back to the engine. However, if the center tube is solid, that would mean that the oil basically comes in thru the tube and swishes around the filter medium, and is then picked up by the same tube? How can this be effective?

On the center tube will be a small hole (IIRC, about 1/3 way down from top) or, in some of the early canister filters, several holes.

The earlier Packard filters had an orifice in the feed tube, came in the bottom, thru the center tube, thru filter, and out the side and in some engines fed the lifter gallery directly. That was changed to route the return into the pan and the pigtail was installed to feed the lifters.

Later filters reversed the flow with oil coming in the side, thru filter, and then thru the center tube with the small hole acting as the flow control and into the pan.

Being partial flow, not entirely sure how much goes thru but safe to say with the small hole (1/16" about), not a lot.

Thanks, Howard. Your description is what I was thinking, but I've examined this closely, and the center tube is completely solid, no holes anywhere, it really just holds the element in place.

I don't have anything older than V8 but will look tomorrow and see where they located that one.

Just looked at a Stude site where a poster had calculated flow on their filters. The orifices he cited are even smaller than I remember -- .045, .050, and .060.

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Take a closer look. The hole is very small and is at about the same level as the inlet fitting on the side. You should be able to see it with good light by looking just over the rim at the top of the housing.

Was just reading an article about Ford flatheads and the fellow said that with the bypass filter all of the oil was filtered every five minutes or so at road speed. I expect Packard will be somewhat similar--in other words the engine is pretty well protected unless it has started throwing chunks. Even then, the floating pickup helps keep them at bay.

The next oil change on the thousanddollarwonder I will check to see how long it takes for the filter to pass a quart and report back.

While maybe not exactly the same as a 54, I did look at a V8 filter assy. Expect they would be very similar over the years. If you can't find the location, wonder if there is a possibility the thing has been plugged with debris.

This hole is 1 1/2" down from the top or as was mentioned, about even with the port on side. A #48 drill is showing the location. #48 size is .076 and fits but the next size up would need to be forced. That makes this hole about .077.

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Thanks, again...I've had the car for 20 years now, and I haven't seen a hole. I will look more closely and report back.

Of course, the other question is why they'd make just one very small hole to pass the oil thru, rather than have it perforated to allow more oil to pass thru more of the filter area..it makes sense to move as much oil as quickly as possible thru as much filter medium to increase filtration and maximize flow...maybe it was the same guy who buried that itty bitty Ultramatic disptick way up there where the sun don't shine?

Good question. Packards used a by-pass oil filtration system as opposed to a full-flow system. The by-pass allows only a small amount of oil flow to go through the filter. This is necessary to preserve pressure and flow to the other parts of the engine. While the filter traps some of the impurities much of it is captured by settling to the bottom of the housing. Ever notice how much gunk is in the bottom when servicing the filter? By-pass does work, but does it differently than the full-flow types. Packard also recommended removing and cleaning the oil pan and pump pick-up screen once per year.

(o[]o)

The bypass filter is more effective than the full flow in that it filters finer. With the correct element the oil will stay clean looking on the dip stick until the filter clogs up.

They did not want to take too much oil away from the engine and could not force very much through the fine filter so they restricted the flow.

The newer theory is to filter all the oil thru a coarser filter and let the fine dirt soot and grit go through the engine. Supposedly there is enough clearance between the parts to let fine dirt go through without doing any harm.

Any filter is better than no filter at all.