Packard Forum Index » V-8 (1955-56)

I'm sorry but it is still not clear to me yet.
Is the engine going into a car or a boat???

Quote:
A sticking relief valve was first noted, as a cause of oil aeration/starvation, in an article on "Noisy Hydraulic Tappets" in SC Vol. 30, No. 3.

This was also addressed in a confidential memo to Zones, regarding a field trial that involved a slight modification to the relief valve and plugging of its bore. That approach, however, was dropped for field service, in favor of the sump tube kit announced in STB 56T-20, regarding hydraulic tappet letdown. Step 3 in that bulletin specifically addresses inspection and repair of the relief valve for sticking.

Meanwhile, plugging of the relief valve bore was only iincorporatedinto the second design pump that was introduced in production - noted in BOTH STB 56T-20 AND SSL No. 936.

While I still think the sump tube kit should be installed on the first design Packard V8 oil pump in case of a sticking relief valve, a greater concern for that condition would certainly be low oil pressure.

As seen with the Hash pump, which is of a completely different design, the condition of a sticking relief valve is not exclusive to the Packard V8 oil pump.

Things like poor maintenance and lack of use further contribute to the problem.

Hi, Brian,

Thanks for recapping all those bulletins in one post.

FWIW, most of the engines from junked cars I pull down have the original oil pump. I seldom ever find one with the plug or dip tube installed or with the second design oil pump.

It can be inferred the combination of being an orphan with a Twin Ultramatic sent many cars to an early death, while the few cars in good enough condition to be restored had better dealer maintenance or the owners are researching the problem and fixing it the second time around.

jack vines

Also there is a passage between the 2 chambers in the base of the pump (intended to lube the gears?) and it was completely blocked with sludge.


Any evidence of lubrication to the shaft area with the Hash. Isn't a suspected lack of lubrication and resulting wear around the shaft in Packard pumps another of the theories as to failures.

Rather than start a new thread about the "fatal flaw" in the Packard V-8 oil pump relief valve design, I'll go with the current thread drift made by Brian and Jack.

Here's a picture of the cross section of the oil pump through the relief valve, spring and sump tube as shown in STAB-56T-20:



Here's a pic of the relief slide valve, spring and gland plug (no sump tube) out of one of my used Packard V-8 oil pumps.



NOTE the discolored area on the side of the slide valve and the recessed surface in the middle. The discolored areas are what causes the sticking in an open position. This is also the part that was supposed to be cleaned off with crocus cloth to "fix" the problem. IMO, the recessed middle exacerbates the sticking problem because the edges tend to snag on parts of the relief hole.

Here's a comparison between the Packard V-8 relief valve assembly and one from a new Olds HV oil pump.



NOTE that the Olds is much larger and has NO recess in the middle. Both are improvements over the Packard design.

Craig

Thanks for the links to the bulletins Brian...makes it much more clear..."a picture is worth.....etc"

Craig, I can see where the recess in the piston could be a sludge magnet, the Hash pump has a smooth piston like the Olds. Oddly tho, the piston in the Hash pump was stuck closed.

I don't have a good clear pic of the relief valve used in the first design pump, but the 55-56 parts book illustration (Plate No. 29A) shows no recess in the original relief valve.

The confidential field trial included cutting two longitudinal "V" scores in that relief valve - half its length, 1/4" apart - to allow trapped oil to move, but prevent entrance of air. I can't say with certainty, however, that the test led to addition of a recess in the valve used in the second design pump (with threaded relief valve plug/bore).

The 55-56 parts book (Gr. 5.1219) also shows that the relief valve piston was originally 1-3/4" long, but reduced to 1" long in the second design. Looking at the comparison pic above, piston from the Melling Olds HV appears to be 2" long.

Sticking was identified as a problem with the first design Packard V8 oil pump, which had a longer relief piston and NO recess.

I'd wanna inspect valves from similar second design pump with same issue before completely condemning the recess design.

Perhaps Keith (PackardV8) can provide some insight from his inspection of second design pump and valve, when his time permits.

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Yes. As BH indicates above the FIRST gen Packard V8 oil pump used a relief valve that resembles the Olds relief valve. The SECOND gen Packard V8 pump (with PLUGGED port) used the relief valve that Craig has pictured above with a recess cut about mid way.

But the INTERNAL cavity allowing for recirculation of over-pressured oil of the first gen pump differes greatly from the second gen pumps cavity also.

So there is a difference in the sliding relief valve AND a difference in the internal cavity between the two different pumps.

Edit: Just for clarity note that ANY packard/hash or 56j oil pump RECIRCULATES over pressure oil INSIDE of the pump. More specifically let me state that the over pressure oil is NOT dumped out of the pump. The over pressure oil is RECIRCULATED back thru the INTERNAL SUCTION side of the pump.

I'll even state it a third way:
Once oil enters the pump there is one, exactly one and only one exit that the oil or any oil that enters the pump can exit. That exit is thru the neck of the pump that bolts to the rear main bearing cap.

See post #35 above by Craig. What he has pictured is the SECOND gen pump sliding valve. NOTE THAT inaddition to the recess it also has a hole drilled thru the side of the sliding valve in the recess. The FIRST gen pump sliding valve has NO hole drilled thru the side what soever.

Good eyes!

The small hole in the second design valve is probably needed because the end of the bore is plugged in that pump. Perhaps this feature corresponds to the "V" grooves that were cut in the original valve for the confidential field trial (where they plugged the relief valve bore on some of the first design pumps).

Of course, that hole is not needed (nor should it be attempted) with the a relief valve bore that's open to the crankcase - even with sump tube.

However, I'm still not sure what the purpose of the recess is on that second design valve.