Olds 350 Rocket oil pressure issue
December 1st, 2018, 05:19 PM
#1
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Olds 350 Rocket oil pressure issue
I had my engine rebuilt and when I put it in and started it only shows 20 PSI it doesn’t go up or down And theres a high volume pump put in and its brand new and running 10 40 oil non synthetic and i have a mechanical oil gauge.
December 1st, 2018, 05:33 PM
#3
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AT SLOW IDLE - 7 PSI MIN.
1500 - 3000 RPM - 35 PSI MIN.
I've always used the general rule of 10psi/1000rpm - it's general but provides a good ball park jump-off.
It would be better if you provided a little more data:
PSI @ IDLE (note your idle RPM)
PSI @ 1000 RPM
PSI @ 2000 RPM
PSI @ 3000 RPM
IMO, if you're getting 20psi at normal idle, you might have a malfunctioning oil pressure sending unit, malfunctioning oil pressure gauge &/or a possible issue between the oil pressure sending unit and the oil pressure gauge.
December 1st, 2018, 06:42 PM
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The only mechanical oil pressure gauges I've used in the past 40 years have been hand-held when reading oil pressure.
None-the-less, I suspect the orifice is clogged with debris - it does not take much debris. In consideration you just had your engine rebuilt, the gauge was working before the rebuild I suspect debris has managed to come into contact & lodge within the gauge - somewhere. I don't know (specifically) the type gauge you have, but here's a highly scientific method.
Literally flood it with carburetor cleaner then blast it with compressed air.
None-the-less, I suspect the orifice is clogged with debris - it does not take much debris. In consideration you just had your engine rebuilt, the gauge was working before the rebuild I suspect debris has managed to come into contact & lodge within the gauge - somewhere. I don't know (specifically) the type gauge you have, but here's a highly scientific method.
Literally flood it with carburetor cleaner then blast it with compressed air.
December 1st, 2018, 06:54 PM
#8
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Sorry, just thought of something. You said you tried another gauge and the other gauge did the same thing, right?
I don't know where you have your mechanical oil pressure gauge installed on your engine system, the type I use I plug directly into the engine oil sending unit orifice/hole. In any case, you might have debris at the point where the line plugs into the engine (or wherever you have your line plugged into the system), or anywhere between where the line plugs in and the orifice where the line plugs into your gauge.
I don't know where you have your mechanical oil pressure gauge installed on your engine system, the type I use I plug directly into the engine oil sending unit orifice/hole. In any case, you might have debris at the point where the line plugs into the engine (or wherever you have your line plugged into the system), or anywhere between where the line plugs in and the orifice where the line plugs into your gauge.
December 1st, 2018, 07:37 PM
#11
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The oil pump getting easier to turn does not sound normal. Vintage Chief's suggestion of putting a mechanical gauge at the sending unit port is the way to go.
If the pressure is low, look at the oil pump and for a galley plug left out. Ask the builder what the main bearing and rod bearing clearances are.
Good luck, I hope this works out to be minor. Don't run it anymore than necessary, only to diagnose the problem.
If the pressure is low, look at the oil pump and for a galley plug left out. Ask the builder what the main bearing and rod bearing clearances are.
Good luck, I hope this works out to be minor. Don't run it anymore than necessary, only to diagnose the problem.
December 1st, 2018, 08:19 PM
#12
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Grab a standard oil pressure gauge from the auto parts store, remove the OEM oil pressure sending unit from the engine, plug in the oil pressure gauge & observe your readings at various RPMs. If you still have no variation in oil pressures with concomitant changes in RPM you know it’s not gauge related and can move forward with further diagnostic measures.
December 2nd, 2018, 05:07 AM
#14
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December 2nd, 2018, 05:12 AM
#15
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Strange that it's sitting at 20 psi and not moving. Priming the motor, it should get harder to turn. What pick up and pan? It could be an issue with the pump, something could be blocking the pick up screen partially or the pick up could be too close to the pan bottom. Just strange to sit at 20. Could any of the galley plugs have been left out?
December 2nd, 2018, 06:52 AM
#16
Gary
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December 2nd, 2018, 07:42 PM
#17
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Just a weird scenario to relate, I once saw an engine start up after a refresh and the oil pressure was low. But the oil filter was bulged. All of the assembly lube from the engine plugged the oil filter. After the filter was changed everything worked normally. Have you changed the oil and filter after startup?
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