Re: 1955 Oil Pumps

Posted by HH56 On 2017/12/17 18:00:29

I think you will probably get many opinions but it is true early 55s had oiling issues -- not so much due to the pump but to "leakage" from other places. The lifters were changed to a different type, rocker shafts were revised to cut down on too much oil being applied to the rocker arms, the cam thrust plate was revised to eliminate a steady stream to the timing chain into an intermittent spurt. All this was done early in the 55 production and sent to the field to be done so if the car was serviced those causes should not be an ongoing issue.

The oil pump has been a continuing guess as to what exactly was the problem. Packard issued a couple of fixes because they thought air was being drawn in thru the pressure relief valve and I believe they also increased the capacity sometime in 56. There is a different casting but I am not totally sure anyone knows exactly what the changes were.. Others have thought that the problem was due to pressure swelling the potmetal plate joining the vacuum pump so they revised the pump with a "fix" to use a heavy metal bottom plate and eliminated the vacuum portion. Others have felt the problem lies in the fact there is no upper bearing or bushing. Misalignment or lack of support for the shaft allowed wear in the cast iron which again allowed air to enter the oil stream. There was another "fix" devised to add a bushing and shaft support for the upper shaft.

The funny thing is the problem is not universal. Some still have their original pumps happily supplying all the pressure needed and other pumps after a short time started allowing air into the system so the lifters start clattering. The Olds pump has a higher capacity and seems to have solved the problem no matter what the original cause but you do give up the aux vacuum pump for the wiper motor. That is easily accommodated by reverting to the dual action fuel pump used in earlier years.