Re: Here is what happened today. What would you do next?

Posted by BH On 2011/8/29 8:46:24

Not to steal any of Keith's thunder, but since he and I kicked this around, offline, some years ago, perhaps I can provide some insight until he is available for further comment.

IIRC, the underlying notion is that any air introduced into the oil stream by the pump builds up in the main gallery, which extends, vertically, to the top of the block. The OE pressure sender/switch taps into that passage.

Trapped as it were, the air builds up (actually, down), until it begins to escape into one of the lifter galleries - thus starving the lifters for oil.

By replumbing the feed for the oil filter as Keith suggests, the air is redirected to the filter cannister, where it is released, harmlessly, through the outlet plumbing.

Keith might have been looking at replumbing as a possible solution to the problem, initially, but has since recommended this as a means of identifying aeration of oil as the problem.

Aeration isn't the only cause of of reduced oil pressure, but - aside from foaming that results from overfilling - its confirmation points to the oil pump as the problem. If its nothing more than a matter of wear at the driving shaft and bore, that can be solved by the approach used by the late Bob Aller (and others), which involves installation of a bushing and truing or replacing the shaft.