no oil pressure(checked with gauge)-Po3oo code

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Beer Man Sam

no oil pressure(checked with gauge)-Po3oo code

Unread post by Beer Man Sam » Wed Jun 24, 2020 9:54 am

5 minutes into driving- loss of power,random misfire(P0300 code). towed car home. Installed gauge in pressure sensor location and needle would not move. 3+ quarts oil drained from pan. Removed,disassembled and inspected pump-no scoring or obvious damage. What else should I inspect?
Thank you

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carriedi
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Re: no oil pressure(checked with gauge)-Po3oo code

Unread post by carriedi » Wed Jun 24, 2020 11:30 pm

what make, model, year and engine are we talking about? Do you have an oil light on or do you show no oil pressure ? Is there any engine noises from running with low or no oil pressure?

Beer Man Sam
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Re: no oil pressure(checked with gauge)-Po3oo code

Unread post by Beer Man Sam » Mon Jun 29, 2020 9:19 pm

2001 Olds Alero 3.4 l displayed oil light in dash. Checked pressure with mechanical gauge-zero. Pulled pan and pump. Pump appeared fine except for a very small gear scrape mark on the end plate(about .002-.003" deep)that was less than a half moon shape. Am working on applying about 10 psi to pump supply port at base of block to explore for excessive leakage. Removed and inspected several rod and main bearings- looked good.
Still trying to locate the "ah-ha" contributor to the problem but know the pump will be replaced.
Any ideas or suggestions would be greatly appreciated.

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carriedi
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Location: Oregon

Re: no oil pressure(checked with gauge)-Po3oo code

Unread post by carriedi » Wed Jul 01, 2020 10:57 pm

that's going to be a tough one. If the pump isn't the problem verify that the pick up screen and tube are clear. find out where your oil pressure relief valve is and make sure it isn't being held open by debris. Make sure there is no leak between the pick up screen and the pump. If there is a gasket or seal on the pick up tube it could cause poor suction or cavitation up at the pump. If the pressure is still low after that then it has to be a leak somewhere upstream from there. Make sure the port for the pressure sensor isn't plugged up. If the port is plugged you won't get a reading for the sending unit or the manual gauge. No oil pressure will usually show up as noisy lifters. Do you hear them making noise? Really bad oil pressure after a time will also cause a rod knock. Hear anything like that starting?

here is an article about low oil pressure on GM vehicles. It's more for later vehicles but parts of the article are relevant to all vehicles.

https://www.noln.net/articles/2223-low- ... ery-filter

Beer Man Sam
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Re: no oil pressure(checked with gauge)-Po3oo code

Unread post by Beer Man Sam » Mon Jul 06, 2020 1:51 pm

Thank you for responding. I have finally achieved a satisfactory seal between the pump discharge port and the inserted rubber hose. I replaced the oil pressure sensor with the same mechanical gauge(verified working accurately when connected to the air compressor) and read 10 psi on it when the compressor was applying the same.
The article from NOLN was helpful and provided a better insight to current engine malfunctions. I have never encountered the drastic loss of oil pressure with engines built over the years. This has been an eye opener for me. You were right on point about the valve train clatter-it was happening. Again I did not drive the vehicle but for a minute before towing it home. The bearing inserts still had oil on them and no apparent damage.
I have ordered a new oil pump and base pan gasket. Soon I hopefully can enjoy driving this vehicle again.
Thank you again Sir.
Beer man Sam

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