Originally Posted By: 440Magnum
Originally Posted By: A_Harman
Originally Posted By: zray
Originally Posted By: A_Harman".........
A lot of oil also can stay in the cylinder head valve boxes if crankcase pressure is too high to allow it to drain.
Now there certainly can be a lot of oil the heads, as it is getting pumped up there, but to say the crankcase pressure is, or could be, holding it up there is not true. The pressure under valve covers or lifter valley, is going to be identical to the pressure down under the crankshaft. There is nothing holding the pressure down below. It is all equalized thru out the engine.
Z
It doesn't take much crankcase pressure to keep oil draining from the cylinder heads. If there is 3" H20 pressure in the crankcase, that is enough to hold more than 3" of oil depth in the cylinder heads.
But the return holes are HUGE compared to the oil supply galleries, at least on most engines. There's no way that a solid "plug" of oil could form in even one of the 1/2" tall by 4" wide drainback passages in a big-block Chrysler, let alone all 8 (4 on each cylinder head).
thank you.
The folks at Melling will tell you that even their high volume pump cannot, and will not, pump the oil pan dry. But people hardly ever listen to facts in this world. They just keep believing what they want to believe.
technically speaking, it's koo-koo.
z