Low Oil Pressure at Idle When Warm

[wjburken]

Do the ‘04’s have a screen filter inline with the oil pressure sensor like the ‘07-‘14’s?

 

[Austen Leach]

I ran shops for over 30 years and when I talked to a customer I asked a bunch of questions to help narrow down the diagnostic procedure. I told them many times that I wanted exact detailed chronological info for what they were experiencing and for what they may have done to try and correct the problem, if they did anything at all. I said many times as an example; "If you only experience the problem on the second Sunday of the month when turning left over the railroad tracks and it is raining at 2 o'clock in the afternoon, I WANT TO KNOW THAT." That is why we ask so many questions.

Gotcha. Ya it literally just did it while I was either sitting at a stop sign, a red light, or I was idling in front of my mom's house about to leave. I can't really remember which one it was because it was a while back and it's started to really bug me because I really don't want something on the engine to go because of low oil pressure. Even though Chevy states 6psi at 1000rpms is still within spec. That makes me a little nervous seeing as how every other 5.3 I've ever driven idles very close to 40psi

 

[Austen Leach]

Do the ‘04’s have a screen filter inline with the oil pressure sensor like the ‘07-‘14’s?

I don't think that they do because AFM didn't start until 2005 but I could be entirely wrong as well.

 

[OR VietVet]

Gotcha. Ya it literally just did it while I was either sitting at a stop sign, a red light, or I was idling in front of my mom's house about to leave. I can't really remember which one it was because it was a while back and it's started to really bug me because I really don't want something on the engine to go because of low oil pressure. Even though Chevy states 6psi at 1000rpms is still within spec. That makes me a little nervous seeing as how every other 5.3 I've ever driven idles very close to 40psi

I would never accept 6 psi at idle. Plus I am more interested of the pressure when under a load at higher rpm's.

 

[live2pull]

Curious if it does it every single time the engine is warm. If not, I would lean more towards an electrical issue (gauge stepper motor). Put a mechanical gauge on there and know for sure.

 

[HiHoeSilver]

Do the ‘04’s have a screen filter inline with the oil pressure sensor like the ‘07-‘14’s?

No.

I don't think that they do because AFM didn't start until 2005 but I could be entirely wrong as well.

You are correct except that AFM didn't start until the gen IV motors in 07.

 

[Austen Leach]

Curious if it does it every single time the engine is warm. If not, I would lean more towards an electrical issue (gauge stepper motor). Put a mechanical gauge on there and know for sure.

Yep every time I drive it it does it. Even if I cut it off and then start it back up or let it cool a little bit and then start it. Once it gets to the operating temperature it just stays around 20ish psi. It’ll be a bit before I can get a mechanical gauge because the end of the month is my bill period lol

 

[SnowDrifter]

Chevy states 6psi at 1000rpms is still within spec.

I don't have much else to add to this thread. Can't say I'm familiar with common issues on these rigs with respect to engine stuff. I know the pickup tube o-ring is common. As is spinning cam bearings on rebuilds. But I do know that 6psi at 1k will cause it to grenade very very quickly. TBH these rigs really need 25+ at ~530rpm hot idle

 

[DougAMiller]

Hate to say this, but it sure sounds like the pick-up tube o-ring. How soon after you replaced it did this start, and what was your reason for replacing it in the first place? Did you do it yourself, or did you have someone else do the work? It is possible that the o-ring was damaged during installation or that it had a defect from the manufacturer.

Like others have said, first thing to do is to connect a mechanical gauge and check to be sure that the gauge in the cluster is accurate. I have also seen oil pressure sensors start to give low readings when they get warmed up.

 

[afpj]

Besides rechecking the oring (might have gotten pinched etc), I've heard of people not seating the tube back in all the way which can cause similar pressure problems as you have described I think. Apparently the tube does have to be shoved in pretty good.

 

[Austen Leach]

Hate to say this, but it sure sounds like the pick-up tube o-ring. How soon after you replaced it did this start, and what was your reason for replacing it in the first place? Did you do it yourself, or did you have someone else do the work? It is possible that the o-ring was damaged during installation or that it had a defect from the manufacturer.

Like others have said, first thing to do is to connect a mechanical gauge and check to be sure that the gauge in the cluster is accurate. I have also seen oil pressure sensors start to give low readings when they get warmed up.

I replaced the o-ring because I thought that it was the issue with the low oil pressure and my oil pan gasket was leaking anyways. The new o-ring was noticeably thicker and didn’t have any nicks or tears that I could see

 

[Austen Leach]

Besides rechecking the oring (might have gotten pinched etc), I've heard of people not seating the tube back in all the way which can cause similar pressure problems as you have described I think. Apparently the tube does have to be shoved in pretty good.

I shoved the tube up, after lubing the o-ring with clean oil, to where it held in place by itself without the bolts in the pickup tube and then torqued the tube bolts. I’m working on getting either a mechanical gauge to check the actual pressure or just replacing the sensor to get that out of the way and check it off

 

[DougAMiller]

I shoved the tube up, after lubing the o-ring with clean oil, to where it held in place by itself without the bolts in the pickup tube and then torqued the tube bolts. I’m working on getting either a mechanical gauge to check the actual pressure or just replacing the sensor to get that out of the way and check it off

Doesn't sound like there's anything wrong with the installation.

I had a low oil pressure problem last year that turned out to be the o-ring. However, I changed the oil pressure sensor first since it is easier to do, and I had to replace it several years ago. The sensor didn't help so I replaced the o-ring, and the pressure was improved, but still low and became somewhat erratic as the engine warmed up. I put the sensor back in that was still sitting on my bench and it's been good ever since.

 

[avalonandl]

You can switch to 10-30 oil with no issues in these engines.

20 psi is enough to float the bearings at idle. If the pressure is up at 35-40 psi on the highway thats really enough.

The fact you are running synthetic is good because it has a higher shear properties.

A mechanical gauge is good to have.

 

[Tonyv__]

Please keep us posted as you diagnose this. I have the same exact problem with my express van that has the 6.0 motor. I replaced my oil sensor but nothing changed. I also run 5w-30 with an ac Delco oil filter...

 

[Austen Leach]

You can switch to 10-30 oil with no issues in these engines.

20 psi is enough to float the bearings at idle. If the pressure is up at 35-40 psi on the highway thats really enough.

The fact you are running synthetic is good because it has a higher shear properties.

A mechanical gauge is good to have.

Float the bearings as in good or bad?

 

[Austen Leach]

Please keep us posted as you diagnose this. I have the same exact problem with my express van that has the 6.0 motor. I replaced my oil sensor but nothing changed. I also run 5w-30 with an ac Delco oil filter...

Just waiting on bills to pass to either go ahead and replace the sensor or grab a mechanical gauge. I'd hate to buy a gauge only to use it one time you know?

 

[Tonyv__]

Just waiting on bills to pass to either go ahead and replace the sensor or grab a mechanical gauge. I'd hate to buy a gauge only to use it one time you know?

I wonder if your local auto part store will rent them? If I get a chance I might try myself

 

[swathdiver]

Well, you replaced the o-ring and checked the pressure sensors and oil filter. Have you filled the motor with 8 or 9 quarts of oil and seen what the pressure is?

 

[Austen Leach]

I wonder if your local auto part store will rent them? If I get a chance I might try myself

I know they rent fuel pressure gauges but I haven’t seen an oil pressure gauge