How Efficient is the Oil filter System on the 331 and 365 Cadillac engines ?

[Bill Balkie 24172]

How efficient  can these  oil filters  be on the 331 and the 365 Cadillac engines ?   If I understand it right the oil enters the top of the canister  feeding from  a 1/8 steel  line .  The oil then passes Through the filter and exits through    approx. 1/16  hole on the vertical pipe inside the oil canister . Then exist Through another 1/8 steel line back into the engine block .  If you have any blockage in the 1/8 steel line between the filter canister and the engine block  the filter will not work .  To make sure the filter was working I removed the filter cartage  and slid a hose over the vertical  inlet tube   over the I/16 hole in the canister and blew compressed air through  the system and could hear air coming out through  the oil fill cap .  Made me feel a little better . Why did  they  use such a small 1/8  tube for the oil to pass through  ?   How does the oil  Feed into the Canister ? Is this filter system efficient in todays standards ?


   Bill

[TJ Hopland]

I believe this is what is called a bypass filter system.   Other option is a full flow system.   In the bypass system only a small amount of the oil is 'bypassed' off the main oil path and flows through the filter.  The filter is much finer than a full flow so it does trap more stuff.  Full flow can't be as fine or it would plug up too quickly due to the volume and pressure it has to deal with. 

[CEC #20099]

Bill: This is a `Bypass` filter system, vs. the full flow systems used on all cars, today. It only filters a small percentage of the oil flowing thru the engine. The small lines limit the engine oil pressure drop thru this antiquated system. These systems started showing up in the late 1930`s, sometimes as a Dealer installation. Cadillac was definitely behind the times in 1955, as other brands had spin-on full flow systems. This is a very inefficient way of attempting to filter oil, but oil Changes were typically recommended at 1000 miles.

c chleboun #20099

[Caddy Wizard]

The bypass oil filter system works fine, if you change the oil regularly, along with the filter.  It not something an owner should worry about...

[Eric DeVirgilis CLC# 8621]

Partial flow oil filtering in Cadillac made its last appearance on the 1959 model with 390.

If any evidence exists of increased engine wear due to the partial flow design, I've never heard of it.

I concur with Art: It should not be an issue so long as oil change recommendations are followed. 

[INTMD8]

I'm not too concerned about the partial flow filter but I would like to change to a PCV system.

[Bill Balkie 24172]

INTMD8

    I rigged up a  PVC system  for  my 365 engine and I never used it  .  I Made it out of Aluminum .  Then decided to use the original  drown draft tube . I can not bring myself to use it .  I figured the car runs very well with the original  down draft tube . I have included a few pictures .

    Bill

[INTMD8]

That's nice!

Mine runs fine as well but occasionally I can smell the crankcase fumes.

I think PCV would do a better job of pulling moisture out of the crankcase as well.

[57eldoking]

Nice PCV setup Bill, it'd be neat to have but just like you I couldn't bring myself to sacrifice the originality. You learn to live with the fumes, they're not that bad.

[Roger Zimmermann]

Mine runs fine as well but occasionally I can smell the crankcase fumes.

Are you not smelling the exhaust indeed? it's what I'm smelling especially on my '56 Biarritz and '57 Brougham as the dual carb set-up is making a very rich idle...

[INTMD8]

Hi Roger. I don't think I am. Smells more like oily crankcase fumes than exhaust or fuel.

The carb seems to be set perfect

[Roger Zimmermann]

Usually cars with one carb can be set in a way the exhaust is not stinking a too rich mixture. I have no problem with my de Ville.
I don't remember, but I don't believe you restored the engine from the '59 car. Maybe too much blow-by?

[INTMD8]

Yes the engine was completely rebuilt.  Doesn't appear to have much blow-by or use much oil. (1/4 quart every 2k miles).

[Jon S]

Getting back to the oil filter discussion - The factory setup works just fine.  Cadillac recommended changing the oil filter every 6,000 miles; the oil every 2,000 miles.  The oil and filter on my 1958 have both been changed every 2,000 miles since new and at 88,000 miles there is no varnish or sludge under the rocker covers or valley pan cover - so I believe the filter system does its job quite well.