Originally posted by Dan Nixon:
by qaz
"Plus, if the problem is that the stock filter doesn't flow enough, as some claim, then how can the problem be that the oil drain passages from the head back to the pan don't flow enough?
If the problem really is that the oil stays up in the heads too long, then putting a high-flow oil filter on will just make the problem worse (assuming that the oil path is pump-filter-heads)."
Just to comment - I do not think I or anyone else claimed the oil filter WAS the problem. More that it COULD BE a problem, and still could. This information suggests that either the oil pump is rapidly pumping ALOT of oil to the heads to lube those 4 fat hollow overhead cams, or the oil is hanging up in the heads along time (or both). The point of the oil filter discussion was that the Motorcraft and other filters had NOT BEEN TESTED to high flow rates that the pump is capable of. This means that the filter bypass mechanism flow capacity was NOT TESTED EITHER. Maybe it works well enough, maybe it doesnt, but I wanted it tested! K&N is the only one that does (and BTW turns out to filter better than Motorcraft in DEMON SVTs oil analysis comparison).
As far as making the problem worse, this makes no sense to me. If the filter IS a restriction, it would mean the oil would just sit in the sump until backpressure dropped. Oil sitting in the sump does nothing, it HAS to be pumped to the heads where gravity lets it drip down to the bearings where it is needed. This information (if accurate) suggests MORE oil is needed in the system - in the stock pan, in a bigger pan, in Accusump etc. Consistant with what I learned from the racers, it explains why baffling is of limited value. A high flow filter will just help ensure that it is pumped efficiently to the heads so it can drip back to the bearings. This info does argue that the filter they were using (presumably Motorcraft but who knows) presumably does flow well enough but I am not sure the case is closed on that either.
I agree with what you are trying to say Dan. The filter itself is not playing a role in the problem at this point if in fact it is true that the oil doesnt drain back to the crancase fast enough. Oil does not drain from the heads and drip on the bearings to lube them. The oil is supposed to drain straight back to the crankcase sump. The bearings are pressure fed from the oil pump through the channels in the block and crankshaft. The qeustion is NOT wether the heads will hold 6 qts. of oil. The fact is they SHOULD NOT hold that much oil! If it is true that they are then some sourt of foul up at engine assembly happened. I have seen improperly installed headgaskets block off the oil drain passages before. Do I think that has happened? Probably not, Unless improper instalation of the headgaskets on THIS particular engine would somehow result in only half of the drain passages being blocked off. One reason I'm waiving the BULL**** flag on this one is, in all of my years of working on engines I've never seen one yet that would run just perfectly with just a 1/2 quart of oil in the sump.[no oil light] That is until you make a hard right hand turn and then all hell breaks loose. Yeah right! So for now I'm waiving the flag.
