P0521 with low oil pressure

Tech discussions on the L77 6.0L V8.
Caprice ltz
Posts: 16
Joined: Tue Sep 13, 2022 2:14 am

P0521 with low oil pressure

Post by Caprice ltz »

Hello.

I have l77 engine and I replace all of these :

All Gasket and seal
All Lifter with Guide
Camshaft with bearing and retainer plate
Crankshaft polishing and use new bearing with 10 size
Oil pump with 030‪4 no. and screen with O-ring
New DOD.

Oil use 5w30

After this I have P0521 code all time and the pressure drop when idling to 56 kpa I replace the oil pressure sensor but code still.
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GammaFlat
Posts: 259
Joined: Mon Sep 21, 2020 9:26 am
Location: NW Indiana

Re: P0521 with low oil pressure

Post by GammaFlat »

Problems I have knowledge of:
  • oil pickup tube 0-ring seal is not seated or wrong size - sucks some oil and some air
  • oil passages for DOD are not blocked off correctly (puking out oil and pressure freely) - friend had this on an engine he bought
Both of these can be fixed "in car". One of them, you take the oil pan off, the other, take the intake and valley cover off
.
Other potential problems that I've not seen with my eyes:
  • oil pump problem - pressure relief spring too short or non-existent or high clearances inside pump
  • missing or high clearance crank bearing - if it's not knocking
  • foot of oil pickup is on bottom of pan (not "clearanced")
Current: 2013 9C3, deeper trans pan, 12VoltSolutions Remote, Class III hitch, Android Auto capable radio
Caprice ltz
Posts: 16
Joined: Tue Sep 13, 2022 2:14 am

Re: P0521 with low oil pressure

Post by Caprice ltz »

O-ring same size and seated.
DOD replaced two time one by used and the last by new one.

The low pressure only after 90c or more when cold 300 kpa and more.
bstoner
Posts: 233
Joined: Wed May 05, 2021 2:12 pm

Re: P0521 with low oil pressure

Post by bstoner »

What about the bypass in the oil pan? Did you plug the secondary oil bypass valve in the oil pan? If your oil pressure readings are accurate then that could be a source of low oil pressure.

P0521 code
- The engine oil pressure is out of its working range.
- The ECM does not detect a change in the engine oil pressure.
- The engine oil pressure is outside of a calculated working range determined by engine speed and temperature.

Troubleshooting the sensor is pretty simple. One wire is ground. One wire is 5v from the ECM. And the other wire is variable positive 1-5v volts from the sensor the ECM uses to calculate oil pressure. Should have less than 10 ohms resistance between plug and ground and 4.8–5.2 volts on plug with key on.
2014 Caprice PPV, 6.0L, BTR Stage 2 Cam, 3.45, 3" exhaust, Rotofab intake, Chris Henry tuned, future LSA....
Caprice ltz
Posts: 16
Joined: Tue Sep 13, 2022 2:14 am

Re: P0521 with low oil pressure

Post by Caprice ltz »

If you mean oil relief valve, Not replace.
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Caprice ltz
Posts: 16
Joined: Tue Sep 13, 2022 2:14 am

Re: P0521 with low oil pressure

Post by Caprice ltz »

Can switch from 5w30 to 10w40 fix??
bstoner
Posts: 233
Joined: Wed May 05, 2021 2:12 pm

Re: P0521 with low oil pressure

Post by bstoner »

In your picture of the connector you measured the #2 pin (right) which is the 5v reference voltage. So that looks good. Next you need to measure the ohms on the #3 pin (left) from the pin to ground. Anything more then 10 ohms indicates a bad ground. The top pin, #1, is the input pin where the variable voltage goes into the ECM so it can convert it to pressure. A small change in oil viscosity is not going to drastically change your pressure. The secondary oil relief valve in the oil pan could be causing your issue. At 1,000 rpm with engine hot the minimium oil pressure should be at least 24 psi stock. First thing I would do is remove the oil pressure switch, install your own gauge and then you will know if it is an internal engine oil pressure issue or external electronic issue. Then troubleshoot from there. What model oil pump is in there and what color spring is in the pump? Also I think there is a small screen underneath the sensor. Check it.
2014 Caprice PPV, 6.0L, BTR Stage 2 Cam, 3.45, 3" exhaust, Rotofab intake, Chris Henry tuned, future LSA....
Caprice ltz
Posts: 16
Joined: Tue Sep 13, 2022 2:14 am

Re: P0521 with low oil pressure

Post by Caprice ltz »

Thanks for your reply and help.

Oil pump # 12710304 ana I am not sure about spring.
I put new screen.
bstoner
Posts: 233
Joined: Wed May 05, 2021 2:12 pm

Re: P0521 with low oil pressure

Post by bstoner »

That is an OEM pump, standard pressure, high volume, so thats fine. Should also rule out internal oil pump spring (42 psi) and rule out secondary bypass unless it is malfunctioning. Next step pull the sensor and put an oil pressure gauge on it to narrow down either mechanical issue or electrical/sensor issue. Also what is the psi with the engine at operating temp and held at 1,000 rpm?
2014 Caprice PPV, 6.0L, BTR Stage 2 Cam, 3.45, 3" exhaust, Rotofab intake, Chris Henry tuned, future LSA....
Caprice ltz
Posts: 16
Joined: Tue Sep 13, 2022 2:14 am

Re: P0521 with low oil pressure

Post by Caprice ltz »

One mechanic said change to #12612289 will fix !!!

At 1000 rpm = less than 24 psi may be 136-150 kpa.
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