Oil Pumps and cavitation: Re-send...

[jmbrodsky@domain.elided]

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     John, et al.
     
        I'm pretty sure that the crankshaft *does* dip into the oil in 
     the pan, else there would be no way for the cylinder walls to be 
     lubricated.  This is also a contributing factor to determining 
     firing order.  The nearby cylinders need to splash oil up while the 
     piston is at TDC.  Also, about cavitation in the pump.  Cavitation 
     is really defined as a pressure drop on the rear side of a pump, 
     thus you end up with a low vapor pressure and effectively boil the 
     fluid.  Ever boil water at room temperature?  Ask me.  Anyway, if 
     the oil were foamed, the pump would continue to pump foamed oil.  
     The pressure would actually be nearly the same, it just wouldn't 
     get to all the little nooks and crannies, as it would pump air into 
     those. Kind of like a brain anuerism from air in the blood.  It 
     gets bubbles into corners where it can't pump oil through.  The 
     crankcase pressure can leak out many different places.  I was 
     really surprised, when I rolled my Scout, just how many places oil 
     came out.  The crankcase pressure can vent off in any number of 
     places, and the foam filled can on the valve cover usually 
     condenses the droplets.  I'll agree with foamed oil having less 
     lube properties, but pressure is pressure, whether over oil or air.
     
        To have the oil level over the seals, it really has to be full.  
     Just for grins, take off the pan, when you go to check in there 
     sometime, and fill it up with 6quarts.  Heck try 10!  It'll leak 
     out the dipstick hole before the end seals, and my guess is that 
     you'll have close to 14 quarts plus to get out the seal.  When my 
     buddy bought his '65 80 with a 345, it smoked terrible!  His 
     dipstick was made from like 2 or three others brazed together, 
     broken, brazed, etc.  You get the idea.  Well, we drained it and 
     9.5 quarts came out.  It didn't leak a drop, but smoked is all.  a 
     dual sump 345 pan will hold 9.5 quarts.  The extra sump is supposed 
     to hold 1qt.  My 392 is running at 7.5 quarts on a regular sump pan 
     and is great. At the recommended 6 quarts, I get valve noise at 70+ 
     mph.  With the extra oil, it's fine.
     
        As far as I have heard the changes with the v8 circa 74 were to 
     enlarge the return ports at the back of the heads?  They get 
     crudded up right quick.
     
        On another topic, has anyone found a REALLY good radiator flush? 
      Like one that get all that rust out of there, or at least make the 
     flow smoother?  My heater core is pretty slow flow, and I think I'm 
     going to dig into it tomorrow.
     
                Just fuel for the fire,
     
        -Joel Brodsky
        '76 Scout II 345/tf727
        '75 T'all 150 4wd 392/tf727
     
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Date: Thu, 04 Dec 1997 17:26:36 GMT
From: jlandry@domain.elided (John A. Landry) 
Subject: Re: engine oil

     
The first I can think of is that the oil level in the sump can be so high 
that the crankshaft actually dips into the oil causing splashing and oil 
foaming.  Oil foaming can lead to excessive amounts of oil being sucked 
into the PCV system and out past engine seals (like the front and rear main 
seals).  Heavy foaming can also be a cause of oil cavitation in the pump. 
Foamed oil can have reduced lubricating qualities.
     
Another problem with high oil level could be the static oil level might be 
above the rear and / or front main seals and pan gasket.  Excessive seepage 
can be the result as these seals and gaskets are constantly fully or 
partially submerged in oil.
     
 jlandry@domain.elided 
     
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