Low Oil Pressure at Idle When Warm

Austen Leach · Jan 20, 2020

DougAMiller said:
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 · Jan 20, 2020

afpj said:
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 · Jan 20, 2020

Austen Leach said:
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 · Jan 20, 2020

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__ · Jan 20, 2020

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 · Jan 20, 2020

avalonandl said:
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 · Jan 20, 2020

Tonyv__ said:
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__ · Jan 20, 2020

Austen Leach said:
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 · Jan 20, 2020

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 · Jan 20, 2020

Tonyv__ said:
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

Low Oil Pressure at Idle When Warm

Austen Leach

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DougAMiller

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