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  • Dropping oil pressure

    The engine in my 56 truck, which has just gone back on the road after an unknown period of hibernation (at least 10 years) is exhibiting some weird oil pressure readings. Engine is a Canadian built 259 from a 63 Daytona. When it starts from cold the pressure shows 50 psi. After idling for a bit it will drop to a steady 40. In gear it will show 30 to 40 while driving around till it gets to operating temp (170-180) then it begins to drop into the 20's both at idle in gear, its got a gm 700r4, and going down the road at 40 or so. When I pull into the driveway to park it, I put it in park, blip the throttle, and she it sattles to idle it will show 30/35 psi. Oil is old and a pint low, no visible leaks, no nasty noises. Going to do a change and filter tomorrow. But wondered what the great minds here might come up with in regard to this fluctating pressure.

  • #2
    Check your oil pressure with a better gauge like a snap on or mac. If still reading the same I would say you have a worn bearing issue or maybe a release valve on the oil pump sticking.

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    • #3
      The gauge is a new aftermarket unit.

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      • #4
        Your numbers do not sound dangerously Low, most Multi-weight Oils do lose pressure when Hot. Also worn Cam Bearings will lose some pressure as the Oil heats up.

        Please note though, that your Oil Pressure Relief Valve is NOT in the Oil Pump as Post #2 mentioned.

        It is at the very Front, Lower Right Side of the Block, forward of the Engine Mount Bracket.
        The Plunger and Spring can be removed, cleaned or replaced easily and may help after or during your Oil and Filter Change.

        Welcome to the SDC Forum.

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        Last edited by StudeRich; 09-27-2016, 04:39 PM.
        StudeRich
        Second Generation Stude Driver,
        Proud '54 Starliner Owner
        SDC Member Since 1967

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        • #5
          I don't find your numbers alarming, especially when you consider that it is old oil. Change the oil and give a report. If the engine has a history of delayed oil changes, change it again in about 1000 miles.

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          • #6
            Does this engine have a by-pass oil filter (add-on style)?
            Restorations by Skip Towne

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            • #7
              Many reading this would feel delighted with the your car's oil pressure in their own vehicles. IMHO you shouldn't have any problems with this engine.

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              • #8
                Yeah, my '58 truck ends up with about 5# on a hot idle..... it's still running.

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                • #9
                  Warm it up and change the oil. I like Valvolene racing oil; don't have to addZZDP to it. The oil pressure relief valves are replaceable ( fairborn Studebaker - Phil Harris) Oil pumps are also rebuildable. Oil pressure is not bad - they would never service a warranty with pressures like that and if you had an idiot light it would never come on.

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