Low oil pressure at cold startup
Thread Starter
4th Gear
Joined: Aug 2023
Posts: 4
Likes: 0
Low oil pressure at cold startup
I have an 04 with a stock LS1 that has 54k miles on it. Recently when I started it, I had a low oil pressure alarm and the gage read "0" for about 5 secs and then went to about 60 -80 psi. It does this now everytime the car sits for about 8 hours. When the engine is warm, I can start it up and oil pressure comes up right away. If it has sat for a few days, I can hear valvetrain clatter for a few seconds when it starts and then goes away. I am at 40% oil life and I replaced the gm oil filter with a Mobile 1 filter and still have the same problem. While driving, the oil pressure reads 40-45 psi and about 30 psi at an idle. The pressure stays constant with no fluctuations.
I not convinced it is the pressure sending unit. Could the problem be with the oil pump, pickup tube o-ring, or something else? Has anyone else experienced this?
Thanks in advance for any advice!
I not convinced it is the pressure sending unit. Could the problem be with the oil pump, pickup tube o-ring, or something else? Has anyone else experienced this?
Thanks in advance for any advice!
Race Director
Joined: Oct 2004
Posts: 12,864
Likes: 4,669
I have an 04 with a stock LS1 that has 54k miles on it. Recently when I started it, I had a low oil pressure alarm and the gage read "0" for about 5 secs and then went to about 60 -80 psi. It does this now everytime the car sits for about 8 hours. When the engine is warm, I can start it up and oil pressure comes up right away. If it has sat for a few days, I can hear valvetrain clatter for a few seconds when it starts and then goes away. I am at 40% oil life and I replaced the gm oil filter with a Mobile 1 filter and still have the same problem. While driving, the oil pressure reads 40-45 psi and about 30 psi at an idle. The pressure stays constant with no fluctuations.
I not convinced it is the pressure sending unit. Could the problem be with the oil pump, pickup tube o-ring, or something else? Has anyone else experienced this?
Thanks in advance for any advice!
I not convinced it is the pressure sending unit. Could the problem be with the oil pump, pickup tube o-ring, or something else? Has anyone else experienced this?
Thanks in advance for any advice!
Race Director
Joined: Oct 2004
Posts: 12,864
Likes: 4,669
Before you tear into it, be sure to use some compressed air and a garden hose to clean around your intake. I would recommend removing the intake to change the sender. Some guys drill a hole in the cowl. I wouldn't do that, but hey, your car, your choice......
Thread Starter
4th Gear
Joined: Aug 2023
Posts: 4
Likes: 0
Thanks for the advice! Been reading up on how to change it. Removing the intake is the best way. No way am I cutting holes in my car!
Melting Slicks
Joined: Nov 2013
Posts: 2,049
Likes: 316
From: USA
Something else you could try is to build oil pressure before starting the engine when it's cold. To see if it shows the same delayed oil pressure symptoms or has oil pressure right away
Key on, then fully depress the accel pedal, crank the engine for 5-10 seconds bursts or whatever until oil pressure shows. The engine will crank but fuel injectors are disabled.
I do this some times after the car has sat a long time and extra oil cooler lines and such probably make it a bit worse in my scenario.
Key on, then fully depress the accel pedal, crank the engine for 5-10 seconds bursts or whatever until oil pressure shows. The engine will crank but fuel injectors are disabled.
I do this some times after the car has sat a long time and extra oil cooler lines and such probably make it a bit worse in my scenario.
Last edited by aaronc7; Aug 13, 2023 at 07:00 PM.
