Re: V-8 oil pumps

Posted by Owen_Dyneto On 2016/7/25 9:55:10

IMO you really have to view the oil pump situation within the context of the entire engine oiling system and I think even at this date we still lack a complete and total explanation for the problems that arise with the engine oiling. Part of the problem in gaining a full understanding is that some V8s like my own have gone nearly 100,000 miles with no engine work whatsoever, and running the original oil pump and has experienced no problems at all; yet others have developed all kinds of valve lifter clatter and excessive bearing wear at less than 1/2 that mileage.

It was not uncommon for first generation new engines to have oiling issues - look at the 1955 Chevrolet 265 V8 which had its share of problems - but they were resolved quickly in part due to the very large volume of units produced. Packard for several reasons did not have the opportunity to fully evaluate and correct their issues. Twice they changed the oiling of the rocker shafts to increase pressure to the lifters, later added oil baffles to the heads, changed to a different hydraulic lifter, and they made several alterations to the oil pump, yet short life on many engines due to poor oiling remains so it seems Packard never fully comprehended the full causation.

Some have placed blame on the combination vacuum and oil pump, yet it performed OK for General Motors who used it for a few years in Cadillac and Buick. Surely the oil pump could have been designed better and most criticism is aimed at the lack of a proper shaft bushing at the driven end, a prevalent therory being that wear eventually allows air to be sucked into the oil stream. Hence the observation by many that simply running 1/2 quart of oil over full solves the lifter clatter problem.

Certainly there are others here far more knowledgeable than me on this and I'm sure they will offer different opinions - if you're really interested there are dozens and dozens of articles and posts on this topic, some dating back to the earliest of days, enough reading to last you the rest of the year if you so wish; my opinion is that we still lack a full understanding.