Re: Deja Vu
Posted by BH On 2011/11/20 11:35:45
Noise from lifters that are otherwise clean and in good working order is clearly due to insufficient supply of oil, but the cases between the Super Eight and the V8 couldn't be more different.
If one considers the service engineering history provided by the relevant <i>Service Letter</i> articles that were published from 1940 through 1947, it becomes apparent that Packard was trying to improve oil supply to the lifters in the Super Eight engine, but ultimately settled on a pump that provided higher volume. Thanks to <i>39super8</i> (Jim), we now know that this was accomplished by gears with a deeper root, plus a larger discharge opening. In spite of that business about bearing clearances opening up, this new pump became standard issue on the '48 Custom Eight engine, which was actually the old 356 mill from the Su8. Yet, if you look back through the parts books, you'll find that the pressure relief valve spring is the same in this new pump as all those before it in this engine. All this suggests that Packard had simply underestimated the additional demand of the new hydraulic tappet technology in their initial oiling system design.
The problem with the V8 is bit more complicated.
After a new lifter design and a few various attempts to modify oil supply to the lifter galleries for the Packard V8, they somehow determined that air was entering the oil stream. Initially, it was though that the source was the pressure relief valve port, while the valve dumps oil internally, there was concern that the vale was sticking, and allowing air to be drawn in on the suction side. After and extensive field test that involved plugging pumps, Packard revised the production oil pump to a plugged style, and with a different pressure valve and spring, but with NO change in gears. However, for field service of the earlier design, it was decided that a tube kit would suffice - such that a sticking valve would draw oil from the sump, rather than air.
There must have been some merit to this approach, or Packard would not have bothered to redesign the pump body and pressure relief valve and spring. In fact, my dad put nearly 75K on the clock of the Exec that he purchased brand new in the April 1956 (which falls in the production range of the late design pump) and it NEVER had a lifter noise. In fact, he never had that engine apart for anything. <i>('Twas lack of parts and competent service for the Twin Ultramatic and the onset of tin-worm that killed the beast.)</i>
However, long after the last Packard engineer turned out the lights in Detroit, reports of lifter noise in the V8s persisted. I believe it was in 1975 that PI first announced a modification service, where the vacuum pump and separator plate was removed in favor for a thicker, bushed, bottom plate. Yet, I could never accept the notion that the problem was the result of the vacuum pump and or separator plate was flexing under pressure. In fact, Studebaker had recommended the same approach as Packard for the 56J Golden Hawk which used the Packard V8 and oil pump, but WITHOUT the vacuum pump. I've even heard of reports of problem persisting even after installing a modified pump from PI.
The very fact that some owners reported relief from overfilling by no more than a half quart of oil is clear evidence that some pumps were drawing air from some other point. As it turns out, it was excessive wear between the driving shaft and its corresponding bore in the pump body. Those claiming the Packard V8 pump had insufficient bushing are misstating the facts; the Packard pump never had bushing at this point - nor did many others. Bob Aller's approach to rebuilding the pump trues up the driving shaft and installs a bushing in the pump body, to fixe the leak. In fact, I personally know of a '56 Packard in this area that had such work done over a decade ago and the car is driven, not trailered, to all sorts of events, year after year, in the Penn-Ohio area - some even hundreds of miles beyond - with no further with problem.
I think the root of the problem with the V8 pump was identified by member <i>PackardV8</i> (Keith Lummus). Attached, below, is a pic that he provided, long ago, at another venue. Notice the small-block Chevy pump (at left) has a cast channel that supplies a trickle of oil, from the output side of the gears, to the driving shaft, where as the OE Packard pump (at right) has none. Give the driving shaft in the Packard pump, even bushed, some oil and it should be fine. I believe that member <i>Ross</i> (Miller) is now doing this with his own rebuilds.
The problem with the Su8 engine was one of mere oil supply, but the ultimate problem with the V8 is one of air diluting the oil stream. IMHO, the Olds HV conversion isn't necessary, but simply an alternative for those who want something other than a properly repaired OE pump.
Yet, no matter which route an owner choose, they need to be mindful to the possibility that collateral damage has already occurred elsewhere in the engine. Simply throwing more oil at the lifters might be masking other issues.
I'm no engineer, but you don't have to be a rocket scientist to see this.
<i>Caveat emptor</i>.
Attach file:
(30.85 KB)
If one considers the service engineering history provided by the relevant <i>Service Letter</i> articles that were published from 1940 through 1947, it becomes apparent that Packard was trying to improve oil supply to the lifters in the Super Eight engine, but ultimately settled on a pump that provided higher volume. Thanks to <i>39super8</i> (Jim), we now know that this was accomplished by gears with a deeper root, plus a larger discharge opening. In spite of that business about bearing clearances opening up, this new pump became standard issue on the '48 Custom Eight engine, which was actually the old 356 mill from the Su8. Yet, if you look back through the parts books, you'll find that the pressure relief valve spring is the same in this new pump as all those before it in this engine. All this suggests that Packard had simply underestimated the additional demand of the new hydraulic tappet technology in their initial oiling system design.
The problem with the V8 is bit more complicated.
After a new lifter design and a few various attempts to modify oil supply to the lifter galleries for the Packard V8, they somehow determined that air was entering the oil stream. Initially, it was though that the source was the pressure relief valve port, while the valve dumps oil internally, there was concern that the vale was sticking, and allowing air to be drawn in on the suction side. After and extensive field test that involved plugging pumps, Packard revised the production oil pump to a plugged style, and with a different pressure valve and spring, but with NO change in gears. However, for field service of the earlier design, it was decided that a tube kit would suffice - such that a sticking valve would draw oil from the sump, rather than air.
There must have been some merit to this approach, or Packard would not have bothered to redesign the pump body and pressure relief valve and spring. In fact, my dad put nearly 75K on the clock of the Exec that he purchased brand new in the April 1956 (which falls in the production range of the late design pump) and it NEVER had a lifter noise. In fact, he never had that engine apart for anything. <i>('Twas lack of parts and competent service for the Twin Ultramatic and the onset of tin-worm that killed the beast.)</i>
However, long after the last Packard engineer turned out the lights in Detroit, reports of lifter noise in the V8s persisted. I believe it was in 1975 that PI first announced a modification service, where the vacuum pump and separator plate was removed in favor for a thicker, bushed, bottom plate. Yet, I could never accept the notion that the problem was the result of the vacuum pump and or separator plate was flexing under pressure. In fact, Studebaker had recommended the same approach as Packard for the 56J Golden Hawk which used the Packard V8 and oil pump, but WITHOUT the vacuum pump. I've even heard of reports of problem persisting even after installing a modified pump from PI.
The very fact that some owners reported relief from overfilling by no more than a half quart of oil is clear evidence that some pumps were drawing air from some other point. As it turns out, it was excessive wear between the driving shaft and its corresponding bore in the pump body. Those claiming the Packard V8 pump had insufficient bushing are misstating the facts; the Packard pump never had bushing at this point - nor did many others. Bob Aller's approach to rebuilding the pump trues up the driving shaft and installs a bushing in the pump body, to fixe the leak. In fact, I personally know of a '56 Packard in this area that had such work done over a decade ago and the car is driven, not trailered, to all sorts of events, year after year, in the Penn-Ohio area - some even hundreds of miles beyond - with no further with problem.
I think the root of the problem with the V8 pump was identified by member <i>PackardV8</i> (Keith Lummus). Attached, below, is a pic that he provided, long ago, at another venue. Notice the small-block Chevy pump (at left) has a cast channel that supplies a trickle of oil, from the output side of the gears, to the driving shaft, where as the OE Packard pump (at right) has none. Give the driving shaft in the Packard pump, even bushed, some oil and it should be fine. I believe that member <i>Ross</i> (Miller) is now doing this with his own rebuilds.
The problem with the Su8 engine was one of mere oil supply, but the ultimate problem with the V8 is one of air diluting the oil stream. IMHO, the Olds HV conversion isn't necessary, but simply an alternative for those who want something other than a properly repaired OE pump.
Yet, no matter which route an owner choose, they need to be mindful to the possibility that collateral damage has already occurred elsewhere in the engine. Simply throwing more oil at the lifters might be masking other issues.
I'm no engineer, but you don't have to be a rocket scientist to see this.
<i>Caveat emptor</i>.
Attach file:
(30.85 KB)
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