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THE OIL PRESSURE GAUGE SHOWS 40# OF OIL PRESSURE WHEN COLD AS THE ENGINE WARMS UP THE PRESSURE DROPS. AFTER SOME TIME THE PRESSURE IS AROUND 12# WITH A MECHANICAL TEST GAUGE INSTALLED AT IDLE AROUND 25# RUNNING FAST. thE ENGINE IS SILENT BUT SHOULD I BE CONCERNED? ALSO WHERE THE OIL PRESSURE SENDER IS INSTALLED THERE IS A TEE THAT HAS A OIL LINE TO A FITTING IN THE CAMSHAFT BORE JUST ABOVE THE SENDER FITTING? ANY IDEAS WOULD BE GREAT THANKS JOHN. USING AMSOIL 10W40 OLD ENGINE OIL

The normal factory oil line plumbing for a 356 engine has the three way tee, 1 for the oil pressure sender, 1 for the line to the oil filter, and 1 for the short pigtail that feeds the hydraulic lifter gallery.

The 356 in my '50 stays around 40# at 45 mph. Have you serviced the oil pan and oil pickup screen (removed the gunk)? Has anyone messed with the spring in the oil pump?

Unless your oil pump inlet screen is partially plugged with gunk, I'd say your oil pressure at 25 psi hot and at road speed is very low and indicative of excessive bearing clearances. A worn pump is possible but not as likely.

With 40 psi cold, you might get a little improvement in that by shimming the oil pump relief spring but I very much doubt it will have any effect at all on the running hot pressure. Best to drop the pan, make sure the pump screen is clean, and drop a few bearing caps for measurements.

G'day JOHN-1,
First post so, to PackardInfo.

And I invite you to include your '40 160 in the Packard Owner's Registry here on PackardInfo!

I did "mess" with the pressure relief valve spring. My '47 Custom Clipper's 356 engine would show about 15 lbs. pressure at idle with the engine at operating temperature and about 35 lbs. pressure at 50-60 m.p.h. These readings on an after market Sewart Warner gauge plumbed into the oil galley line to the rear main bearing. There are a series of plugs for the main bearings on the RH side of the engine. The stock oil pressure gauge, plumbed into three-way tee at the LH front of the engine, gives consistently lower reading.

The engine never made any lifter noises or any other kind, but the pressure was low through out the speed range.

I shimmed the relief valve spring with a flat washer, or washers. I don't recall how many washer shims I installed, but it is easy to experiment for results. The shimming improved the running pressure by about 5-10 lbs., but did not make much difference with the idle pressure. The SW oil pressure gauge now indicates 40-45 lbs. at highway speeds. Idle pressure is up a bit. Probably gained about a 20% increase in pressure, overall.

I am using 15W-40 Classic Car Motor, sold by the Indiana Region of the CCCA.

(o[]o)

SOUNDS LIKE I NEED TO PULL OIL PAN OFF AND LOOK FOR GUNK AND PLASTI GAUGE SOME BEARINGS tHANKS JOHN

ILL PULL THE OIL PAN AND LOOK FOR GUNK AND PLASTIGAUGE SOME BEARINGS THANKS JOHN

SHIMMING THE SPRING SEEMS EASY ENOUGH ILL TRY IT THANKS JOHN

JOHN-1, using all caps is the equivalent of shouting. Most folks use lower case unless they are trying to MAKE A POINT!

Packard had a service bulletin that changed the oil routing on the oil filter. Basically they put a restrictor in the line to the oil filter and then dumped the oil into the crankcase by the oil filler tube. Check to see what your oil routing is and if you have the restrictor.