Low Oil Pressure at Idle When Warm

[Austen Leach]

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?

I haven’t actually checked the pressure sensor. Is there a way to do this? I also have not put 8 or 9 quarts of oil in it. Wouldn’t that just tell me if the pickup tube o-ring was bad?

 

[avalonandl]

Float the bearings as in good or bad?

Good, the bearings in your crank "float " on a film of oil. You need that for them to work as designed.

 

[Austen Leach]

Good, the bearings in your crank "float " on a film of oil. You need that for them to work as designed.

Gotcha. Glad to know I might not be doing any damage driving it like this till I can solve the problem

 

[swathdiver]

I haven’t actually checked the pressure sensor. Is there a way to do this? I also have not put 8 or 9 quarts of oil in it. Wouldn’t that just tell me if the pickup tube o-ring was bad?

I thought you had swapped it out. The other way would be to view data from scan tool and compare to dash and then of course a mechanical gauge. As for the o-ring, yes, over-filling would submerge the o-ring and eliminate starvation if it was pinched or rotten.

 

[Austen Leach]

I thought you had swapped it out. The other way would be to view data from scan tool and compare to dash and then of course a mechanical gauge. As for the o-ring, yes, over-filling would submerge the o-ring and eliminate starvation if it was pinched or rotten.

The Solus I have won’t read actual oil pressure so I can compare it to the dash but it does give me oil pressure switch voltage which is sitting at 1.41-1.52 with the dash showing oil pressure at 30psi and coolant temp at 158 degrees Fahrenheit

 

[Fless]

That sender voltage tracks with mine ('04 5.3 Flex):

Gauge Oil Sensor
Pressure_ Voltage (v)

0 (engine off) 0.53
35 1.69
40 1.86
45 2.06
50 2.29
60 2.41

That doesn't mean that your sender isn't under-reporting the actual oil pressure, though. Only way to verify that is with a direct pressure gauge.

 

[Austen Leach]

That sender voltage tracks with mine ('04 5.3 Flex):

Gauge Oil Sensor
Pressure_ Voltage (v)

0 (engine off) 0.53
35 1.69
40 1.86
45 2.06
50 2.29
60 2.41

That doesn't mean that your sender isn't under-reporting the actual oil pressure, though. Only way to verify that is with a direct pressure gauge.

I’ll double check the voltages tomorrow. I’m trying to do all the diagnostics I can until I can afford to get a mechanical gauge or just replace the sensor

 

[SnowDrifter]

I’ll double check the voltages tomorrow. I’m trying to do all the diagnostics I can until I can afford to get a mechanical gauge or just replace the sensor

Lot of auto parts stores rent them for free, sans deposit which you get back

 

[bondservant2]

is the o-ring problem an issue on the later (07-13) 6.0 engines..? I’ve always thought my K2500 should have better oil pressure. About 20 at warm idle. I haven’t owned a GM product for years and this one only a few months.

 

[wjburken]

is the o-ring problem an issue on the later (07-13) 6.0 engines..? I’ve always thought my K2500 should have better oil pressure. About 20 at warm idle. I haven’t owned a GM product for years and this one only a few months.

Yep.

 

[Austen Leach]

Lot of auto parts stores rent them for free, sans deposit which you get back

None of my local parts stores rent oil pressure testers. The only pressure gauges they have are compression and an electronic fuel pressure gauge

 

[Tonyv__]

I thought you had swapped it out. The other way would be to view data from scan tool and compare to dash and then of course a mechanical gauge. As for the o-ring, yes, over-filling would submerge the o-ring and eliminate starvation if it was pinched or rotten.

I might try this to see if my o ring is bad.. however after testing. Should I drain it back down to 6qts? I’ve always heard overfilling was bad for the engine but I don’t actually have any evidence to back that up

 

[swathdiver]

I might try this to see if my o ring is bad.. however after testing. Should I drain it back down to 6qts? I’ve always heard overfilling was bad for the engine but I don’t actually have any evidence to back that up

Well, I thought so too with these engines but a fella on here was down on his luck and kept his over-filled for two years until he could afford to get it fixed.

 

[SnowDrifter]

I might try this to see if my o ring is bad.. however after testing. Should I drain it back down to 6qts? I’ve always heard overfilling was bad for the engine but I don’t actually have any evidence to back that up

Overfilling is bad when the crankshaft dips into the oil and whips it into a foam.

You can tell by running your rig for a few mins and quickly pulling the dipstick out to inspect while running.

FWIW I run 7 quarts in mine. I run the long filter but it doesn't displace an appreciable amount. No aeration issues

Edit: brain dump. Not sure about front or rear seals. IIRC they're primarily to guard against oil spash vs oil butting up against it. I suppose it could worsen a leak if there's a pool of oil sitting against the things, but then again, if it doesn't seal there, I can't see it sealing in general. And besides those points, if your running oil level is that high, your engine is trying to make a nice whipped topping out of your oil.

 

[avalonandl]

Do NOT run overfilled it causes the oil to foam which is BAD.

You can run maybe 1/2 quart high but 8-9 quarts is way to much.

 

[Tonyv__]

Do NOT run overfilled it causes the oil to foam which is BAD.

You can run maybe 1/2 quart high but 8-9 quarts is way to much.

Are you saying I shouldn’t even over fill just to test the o ring theory? Or I shouldn’t overfill and leave it in the engine for a long period of time.

 

[avalonandl]

Are you saying I shouldn’t even over fill just to test the o ring theory? Or I shouldn’t overfill and leave it in the engine for a long period of time.

You can overfill it to test it but drain back down before driving.

Oil that has foam in it is actaually air bubbles and will not provide consistent oil coverage on bearings.

 

[Tonyv__]

You can overfill it to test it but drain back down before driving.

Oil that has foam in it is actaually air bubbles and will not provide consistent oil coverage on bearings.

gotcha. Thank u for clearing that up

 

[Austen Leach]

I’ve got a little update/addition to this issue. Yesterday I drove to Arlington to pick up a 2/4 drop kit for my cousin’s truck. I checked my oil before I left and it was right in the middle of the crosshatching. I ran about 85mph the entire way there and back. Got in the Tahoe the next morning and started it up to run and grab some coffee and the dash read “check oil level”. Pulled the stick and nothing on it. I topped off the oil back to about 3/4 up on the crosshatching and crawled under the truck to ensure I didn’t have a massive leak somewhere. I have a tiny tiny rear main leak but nothing ever touches the ground and nothing is blown back on the transmission or anything. Also after I went to the coffee shop and went out and started the Tahoe I had a decent smoke cloud come out from the exhaust. I was in the shop for about 35 minutes and my windows are tinted extremely dark so I couldn’t really see the color of the smoke but I’m not losing any water and my oil doesn’t look milky or anything

 

[avalonandl]

Your sucking oil thru your pcv is my bet. At high speed cruising.