1956 Cadillac Oil Filter canister operation?

[carguyblack]

I took off my oil filter canister as part of my engine removal and was trying to figure out the circulation of oil through it. It was pretty gunky.  Both the upper and lower lines blow freely once they were off the canister. However, the oil was just sitting in the canister and not draining through the lower tube. I have cleaned it thoroughly now and checked the service manual for any help and can't find how the oil is supposed to pass through the lower tube back into the engine. I put a cup of oil in the cleaned canister and it just sits at the bottom and goes nowhere. The center tube holding the filter is solid to the top and then a bolt holds the lid to it with no oil ports in it that I can see. What am I missing? I'm baffled how oil is supposed to circulate through this thing!
Thanks for your help,
Chuck

[vegas49er]

Hi, If it's the same as a 57 (I believe it is) then the oil comes in through the side of the canister and it exits out a small hole in the tube just below where the cover retaining bolt goes. Look closely about 1/3 of the way down and you will see the hole. Sadly this is not a full flow system and is not shall we say modern but better than nothing. No it will never drain back down for you thus the mess and or gunk. F.J.

[Caddy Wizard]

I don't remember exactly, Chuck.  But doesn't the lower line communicate with the central tube that is threaded at the top to secure the cover?  I think the oil goes into (or out of) the sides of that tube.  So the oil will just sit there in the bottom of the can when the engine isn't running. 

I could be wrong, but I think that the oil comes up through the bottom line, through the tube, out thru hole(s) in the tube, out through the filter and then returns through the side pipe.  I think that is how it goes. I think the oil level will stay at the level of the outlet pipe on the side of the canister when the engine is not running.  But the flow could be the exact reverse and I could be wrong!

[carguyblack]

Thank a lot, guys! I now see the little hole on the side of the center tube. I can't believe that the Cadillac engineers who built the monster engine thought that just a small port hole could circulate enough oil through the filter to be meaningful. Seems way under sized for flow. Oh well, at least I know mine is as it was from the factory and functions, however lacking the design may be. Thanks for the reassurance. I was thinking this may have been part of the cause for all the engine clatter.
Chuck

[Roger Zimmermann]

I don't remember either which line is in or out. To know it: you can loose a bit the flared nut at the block or at the canister, start the engine. You will immediately see at which one line there is oil pressure...In know this method can create a mess, so it's better to have someone at the wheel to shut down the engine rather quickly.
The oil cannot drain back completely because, at each engine start, it would takes too long to fill the canister to have full pressure in the circuit.

[fishnjim]

You have to clean out the bowl each oil change or you're putting contaminates back in your motor.   It's messy but necessary(I think).   Be safe, wear nitrile gloves.  Some check and clean the pan also on these part filterers.   It should at least be inspected so you can monitor.  If a bunch of sludge rolls out with the first drainings, it can't hurt.

There's an old post from 2014 that shows the oil flow on a 365.  Google: '56 oil filter flow.   I sold my '56 manual so I don't have. 
The '58 one isn't as complete.   People knew this at the time, so it wasn't documented as well.   I'm sure it's similar to all these blocks.   They rearranged the brackets to change external locations a few times but all work the same.   I even get confused from time to time which one is which and I just went through a rebuild in the last year, and we tried to change to full flow and it wasn't feasible without a separate system.
but for sure; they're partial filtration filters.   
Not until 1961 did Cadillac go to full flow because it took a block redesign to accomplish.   These "'50s" blocks(thru '60) are all off the same original V8 casting more or less.  They changed the internals, etc to increase displacement and HP.
When you look back you have to understand the conditions and knowledge of the day.   They were designed in a time when motor oil was very inexpensive relative to today, they were focused on providing lubrication, not filtering.  Changing frequently was cheaper than adding costly parts.   So there was no reason as they didn't know or have to deal with what we know today.   One can't judge period engineering based on today's thinking and economics.   As economics change, hence, engineering changes.   Otherwise, we'd be legit cursing them for not having MP3 players were they had vacuum tubes.

[cadman56]

Vegas49er is absolutely correct.  The 56 is the same.  Making the drain hole in the center tube larger would only compromise the engine oil pressure.
Get a hand held suction gun ( sort of like a grease gun ) and use it to clean out the filter canister.
Good luck,
Larry

[Lexi]

I use a very large hospital grade syringe, (without the needle), to draw the oil out of the housing during an oil change. Almost the same size as a turkey baster (which may also do the trick). About 6 applications or so is required to draw the remaining oil out of the housing. Roger was correct in that the oil never seems to completly drain back into the engine so you must remove it. I then wipe the inside clean and dry, then replace what I removed with fresh oil, & finish by installing a new filter. Have removed 2 such housings from parts engines that had not run in many years and they both still contained a lot of oil. Clay/Lexi

[carguyblack]

I have been using a turkey baster to remove the oil in the past but I always thought that it was remaining in there because of some sort of malfunction. As my engine began to deteriorate, I was trying to point to a cause other than age that may have contributed to its demise.
I didn't mean to denigrate the engineers of the era and that makes perfect sense considering the economics of the era. Whichever way you want to slice it, these cars are pretty amazing rolling artwork. Thanks for the helpful insights all!
Chuck

[Lexi]

Thanksgiving dinner has not tasted quite right at Chuck's place for years! Clay/Lexi

[carguyblack]

  Funny man!