Low oil pressure when cold is almost always O-ring.
Low Oil Pressure - 2005 GMC Sierra 5.3
- Thread starter SierraMan
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Originally Posted by clinebarger
Originally Posted by SierraMan
OK Guys, thank you for all your insight and suggestions regarding my problem. Just to clarify, I did have the oil pressure sensor replaced last fall. The mechanic that did the work told me that the screen was in good condition (no signs of contaminants on the screen). I used the 5W20 oil because I thought it would result in easier starting at low temperatures.
Regarding my oil pressure at highway speeds (2300 RPM), the gauge reads around 40 psi (275 kpa) .
I will change the oil to 10W30 full synthetic and change the oil filter to the longer style (like a Fram Ultra) and post the results that I have.
I will also change out the thermostat as I find that it seems to take a very long time for the engine to reach operating temperature. Perhaps it is just a matter of a high mileage engine, but a change of thermostat may help?
Does anyone if there is a way to adjust the low idle speed on this engine? It currently runs at about 600 RPM, and I think that a slightly higher RPM would help to keep the oil pressure up?
Gen III engines don't have a screen under the EOP sensor! The only way to adjust target idle speed is with tuning software.
The OP has a 2005 5.3 engine. That's a Gen IV engine. Did I miss something here?
Originally Posted by SierraMan
OK Guys, thank you for all your insight and suggestions regarding my problem. Just to clarify, I did have the oil pressure sensor replaced last fall. The mechanic that did the work told me that the screen was in good condition (no signs of contaminants on the screen). I used the 5W20 oil because I thought it would result in easier starting at low temperatures.
Regarding my oil pressure at highway speeds (2300 RPM), the gauge reads around 40 psi (275 kpa) .
I will change the oil to 10W30 full synthetic and change the oil filter to the longer style (like a Fram Ultra) and post the results that I have.
I will also change out the thermostat as I find that it seems to take a very long time for the engine to reach operating temperature. Perhaps it is just a matter of a high mileage engine, but a change of thermostat may help?
Does anyone if there is a way to adjust the low idle speed on this engine? It currently runs at about 600 RPM, and I think that a slightly higher RPM would help to keep the oil pressure up?
Gen III engines don't have a screen under the EOP sensor! The only way to adjust target idle speed is with tuning software.
The OP has a 2005 5.3 engine. That's a Gen IV engine. Did I miss something here?
Last edited:
Originally Posted by SierraMan
OK Guys, thank you for all your insight and suggestions regarding my problem. Just to clarify, I did have the oil pressure sensor replaced last fall. The mechanic that did the work told me that the screen was in good condition (no signs of contaminants on the screen). I used the 5W20 oil because I thought it would result in easier starting at low temperatures.
Regarding my oil pressure at highway speeds (2300 RPM), the gauge reads around 40 psi (275 kpa) .
I will change the oil to 10W30 full synthetic and change the oil filter to the longer style (like a Fram Ultra) and post the results that I have.
I will also change out the thermostat as I find that it seems to take a very long time for the engine to reach operating temperature. Perhaps it is just a matter of a high mileage engine, but a change of thermostat may help?
Does anyone if there is a way to adjust the low idle speed on this engine? It currently runs at about 600 RPM, and I think that a slightly higher RPM would help to keep the oil pressure up?
Just to feed back since I asked the question on the highway oil pressure. My Gen IV 2008 6 liter indicates 40 psi at highway speed, and the hot idle is around 30 psi at 600 rpm. (Assuming the gages are correct). This is with 5w30 QSUD Synthetic and 180,000 miles. Just to check, is your engine really a 2005 or is it maybe a 2007. Also, do you know if it has AFM or not? Thanks.
OK Guys, thank you for all your insight and suggestions regarding my problem. Just to clarify, I did have the oil pressure sensor replaced last fall. The mechanic that did the work told me that the screen was in good condition (no signs of contaminants on the screen). I used the 5W20 oil because I thought it would result in easier starting at low temperatures.
Regarding my oil pressure at highway speeds (2300 RPM), the gauge reads around 40 psi (275 kpa) .
I will change the oil to 10W30 full synthetic and change the oil filter to the longer style (like a Fram Ultra) and post the results that I have.
I will also change out the thermostat as I find that it seems to take a very long time for the engine to reach operating temperature. Perhaps it is just a matter of a high mileage engine, but a change of thermostat may help?
Does anyone if there is a way to adjust the low idle speed on this engine? It currently runs at about 600 RPM, and I think that a slightly higher RPM would help to keep the oil pressure up?
Just to feed back since I asked the question on the highway oil pressure. My Gen IV 2008 6 liter indicates 40 psi at highway speed, and the hot idle is around 30 psi at 600 rpm. (Assuming the gages are correct). This is with 5w30 QSUD Synthetic and 180,000 miles. Just to check, is your engine really a 2005 or is it maybe a 2007. Also, do you know if it has AFM or not? Thanks.
Originally Posted by Snagglefoot
Originally Posted by clinebarger
Originally Posted by SierraMan
OK Guys, thank you for all your insight and suggestions regarding my problem. Just to clarify, I did have the oil pressure sensor replaced last fall. The mechanic that did the work told me that the screen was in good condition (no signs of contaminants on the screen). I used the 5W20 oil because I thought it would result in easier starting at low temperatures.
Regarding my oil pressure at highway speeds (2300 RPM), the gauge reads around 40 psi (275 kpa) .
I will change the oil to 10W30 full synthetic and change the oil filter to the longer style (like a Fram Ultra) and post the results that I have.
I will also change out the thermostat as I find that it seems to take a very long time for the engine to reach operating temperature. Perhaps it is just a matter of a high mileage engine, but a change of thermostat may help?
Does anyone if there is a way to adjust the low idle speed on this engine? It currently runs at about 600 RPM, and I think that a slightly higher RPM would help to keep the oil pressure up?
Gen III engines don't have a screen under the EOP sensor! The only way to adjust target idle speed is with tuning software.
The OP has a 2005 5.3 engine. That's a Gen IV engine. Did I miss something here?
Yes. Gen 4 started in 2007 in trucks.
Originally Posted by clinebarger
Originally Posted by SierraMan
OK Guys, thank you for all your insight and suggestions regarding my problem. Just to clarify, I did have the oil pressure sensor replaced last fall. The mechanic that did the work told me that the screen was in good condition (no signs of contaminants on the screen). I used the 5W20 oil because I thought it would result in easier starting at low temperatures.
Regarding my oil pressure at highway speeds (2300 RPM), the gauge reads around 40 psi (275 kpa) .
I will change the oil to 10W30 full synthetic and change the oil filter to the longer style (like a Fram Ultra) and post the results that I have.
I will also change out the thermostat as I find that it seems to take a very long time for the engine to reach operating temperature. Perhaps it is just a matter of a high mileage engine, but a change of thermostat may help?
Does anyone if there is a way to adjust the low idle speed on this engine? It currently runs at about 600 RPM, and I think that a slightly higher RPM would help to keep the oil pressure up?
Gen III engines don't have a screen under the EOP sensor! The only way to adjust target idle speed is with tuning software.
The OP has a 2005 5.3 engine. That's a Gen IV engine. Did I miss something here?
Yes. Gen 4 started in 2007 in trucks.
When you chase this down, please let us know what it was. I "inherited" a 2005 C2500 with the 6.0 that had an oil pressure problem.
Changed oil and filter, no change. Replaced sensor, nada. Took a while to get the proper fitting on a pressure guage, and I had to be a contortionist to thread it, but I verified the pressure was low at the sensor. Changed out the o-ring and oil pump (way too involved for what should have been a simple job) with no improvement. Ran out of time and sold the truck "as is" without finding the problem.
Changed oil and filter, no change. Replaced sensor, nada. Took a while to get the proper fitting on a pressure guage, and I had to be a contortionist to thread it, but I verified the pressure was low at the sensor. Changed out the o-ring and oil pump (way too involved for what should have been a simple job) with no improvement. Ran out of time and sold the truck "as is" without finding the problem.
My work truck is a 2005 Silverado 4.8. It has almost 200k miles. Oil pressure was always really good like over 40 psi at idle hot. Then it seemed like within a matter of days I noticed it was low (like 25 at idle). I also smelled some oil so I assumed bad sending unit. We checked and it wasn't leaking. I still assumed either sending unit or the gauge (speedometer already hadn't worked in a couple years and now the volts gauge goes up to 19 occasionally so that gauge is failing also.
Well we got the next oil change and the pressure jumped right back up to the way it was before, so I assumed it was an issue with the previous filter. Fast forward about 1200 miles and the pressure is down again. It's fine cold and it rises with rpm but it's about 25 at idle and less than 40 at 1800 rpm cruising where it used to be like 50-60.
I'm kind of stumped because the oil looks like new (it basically is with only about 1500 miles on it). No signs of coolant getting in. It's still at the full mark. Maybe an injector is leaking and diluting the oil with fuel? No noises from the engine, it runs perfectly as it always has. I'm considering changing the oil again just to see what happens, but I don't own the truck and it's not really my call to change it early. The owner doesn't care how much longer it lasts because he tries to stagger the years of the vehicles and he's worried about having to replace 2 of the 3 trucks at once (next oldest is a 2010 Tacoma with 100k so I think he's worried for no reason). All the trucks have been outlasting his expectations since they got rid of the last ford lol.
Well we got the next oil change and the pressure jumped right back up to the way it was before, so I assumed it was an issue with the previous filter. Fast forward about 1200 miles and the pressure is down again. It's fine cold and it rises with rpm but it's about 25 at idle and less than 40 at 1800 rpm cruising where it used to be like 50-60.
I'm kind of stumped because the oil looks like new (it basically is with only about 1500 miles on it). No signs of coolant getting in. It's still at the full mark. Maybe an injector is leaking and diluting the oil with fuel? No noises from the engine, it runs perfectly as it always has. I'm considering changing the oil again just to see what happens, but I don't own the truck and it's not really my call to change it early. The owner doesn't care how much longer it lasts because he tries to stagger the years of the vehicles and he's worried about having to replace 2 of the 3 trucks at once (next oldest is a 2010 Tacoma with 100k so I think he's worried for no reason). All the trucks have been outlasting his expectations since they got rid of the last ford lol.
It's not always just the Pick-up tube O-ring......I've seen the Oil Pan Gasket cause low oil pressure as well. The oil flow in & out of the Filter passes through the pan gasket. The internal leak will be inside the oil pan where you can't see it.
Generally a new oil pan gasket is installed while replacing the pick-up O-ring........
Generally a new oil pan gasket is installed while replacing the pick-up O-ring........
Originally Posted by clinebarger
It's not always just the Pick-up tube O-ring......I've seen the Oil Pan Gasket cause low oil pressure as well. The oil flow in & out of the Filter passes through the pan gasket. The internal leak will be inside the oil pan where you can't see it.
Generally a new oil pan gasket is installed while replacing the pick-up O-ring........
Is this issue typically just lower oil pressure across the board?
It's not always just the Pick-up tube O-ring......I've seen the Oil Pan Gasket cause low oil pressure as well. The oil flow in & out of the Filter passes through the pan gasket. The internal leak will be inside the oil pan where you can't see it.
Generally a new oil pan gasket is installed while replacing the pick-up O-ring........
Is this issue typically just lower oil pressure across the board?
Originally Posted by caprice_2nv
Is this issue typically just lower oil pressure across the board?
It can act just like the Pick-up O-ring....As the aluminum pan swells with heat, The leak will be minimized. As it cools back down....It will open back up & drain the oil from the upper-end of the engine similar to a bad anti drain back valve.
An actual O-ring issue will aerate the oil upon a cold start......I over fill the sump by 2 quarts....Raise the back of the car/truck with a lift about 20-30 degrees.
Cold start the engine while observing the oil pressure.....If the symptoms disappear, You have a Shrunk O-ring!
Is this issue typically just lower oil pressure across the board?
It can act just like the Pick-up O-ring....As the aluminum pan swells with heat, The leak will be minimized. As it cools back down....It will open back up & drain the oil from the upper-end of the engine similar to a bad anti drain back valve.
An actual O-ring issue will aerate the oil upon a cold start......I over fill the sump by 2 quarts....Raise the back of the car/truck with a lift about 20-30 degrees.
Cold start the engine while observing the oil pressure.....If the symptoms disappear, You have a Shrunk O-ring!
Originally Posted by clinebarger
Originally Posted by caprice_2nv
Is this issue typically just lower oil pressure across the board?
It can act just like the Pick-up O-ring....As the aluminum pan swells with heat, The leak will be minimized. As it cools back down....It will open back up & drain the oil from the upper-end of the engine similar to a bad anti drain back valve.
An actual O-ring issue will aerate the oil upon a cold start......I over fill the sump by 2 quarts....Raise the back of the car/truck with a lift about 20-30 degrees.
Cold start the engine while observing the oil pressure.....If the symptoms disappear, You have a Shrunk O-ring!
I just realized this morning, my work truck appears equally low on cold start. Basically the same as when it's hot. I don't think I can rule out the gauge yet.
Originally Posted by caprice_2nv
Is this issue typically just lower oil pressure across the board?
It can act just like the Pick-up O-ring....As the aluminum pan swells with heat, The leak will be minimized. As it cools back down....It will open back up & drain the oil from the upper-end of the engine similar to a bad anti drain back valve.
An actual O-ring issue will aerate the oil upon a cold start......I over fill the sump by 2 quarts....Raise the back of the car/truck with a lift about 20-30 degrees.
Cold start the engine while observing the oil pressure.....If the symptoms disappear, You have a Shrunk O-ring!
I just realized this morning, my work truck appears equally low on cold start. Basically the same as when it's hot. I don't think I can rule out the gauge yet.
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