Hey Guys … I have survived the cold winter (-10 to +15 deg F) and nursed my old Sierra (150,000 miles) through the worst of it. I did change the oil last fall to Castrol Syntec 5w20 full synthetic. However, as the temperatures dropped, I began to have difficulty in keeping the oil pressure up after a cold start. I would have to sit in the truck with my foot on the accelerator (keeping the RPM at around 1200 to 1500) in order to keep the oil pressure between 15 and 20 psi. As soon as the engine reached normal operating temperature everything was fine, and the engine maintained normal oil pressure at idle. We now have more moderate temperatures (25 t0 35 deg F),. but I still have to keep the RPM's up during a cold start. I am thinking of changing the oil to a 10W30 (or even a 15 W40) to attempt the get the low oil pressure problem under control. Does anyone have any experience with this type of problem? Any other suggestions?
Low Oil Pressure - 2005 GMC Sierra 5.3
- Thread starter SierraMan
- Start date
- Status
Have had several and currently 3 of these GMT 800 rigs lol. 2 '01 Suburban's and 1 05 Silverado Z71 5.3
Thicker oil wouldn't hurt but I would also check:
Oil pressure sensor
Oil pickup tube o ring seal
Oil Pump
Last 3 out 7 of the GMT 800's have been the oil pickup o ring seal, A B*tch of a job if you have a 4x4 model
Dave
Thicker oil wouldn't hurt but I would also check:
Oil pressure sensor
Oil pickup tube o ring seal
Oil Pump
Last 3 out 7 of the GMT 800's have been the oil pickup o ring seal, A B*tch of a job if you have a 4x4 model
Dave
I'm having somewhat similar issues on an Impala 5.3 LS4. Low oil pressure when cold, zero issues when hot. Based on my thread (thanks to: mattd, Trav, and clinebarger
), the suspects are the AFM oil pressure relief valve (not sure if applicable), or the pressure regulator. May want to check my thread for a few interesting tidbits of info. Link:
LS4 P0521 *After* replacing VLOF and sensor?
LS4 P0521 *After* replacing VLOF and sensor?
Use a mechanical oil pressure to verify the actual oil pressure.
Try a new oil filter. Unlikely but a cheap and easy thing to try.
Try a new oil filter. Unlikely but a cheap and easy thing to try.
Sounds like you need a thinner 0w than thicker, since all is fine after warm up. If the oil is thick and hits the oil filter back pressure can go so high the oil pump relief valve opens and takes away flow, which lowers pressure. If your block bypass valve is stuck closed this makes the oil pump go into relief faster. So try the longer oil filter version for your truck, like OE or Fram Ultra with 0w-30 or 20 oil. If that still doesn't work, check the bypass valve and replace if needed.
Once you are up to temperature ( 210 F or so) what is your oil pressure. Also what is your oil pressure at highway speed.
Originally Posted by GMguy84
Have had several and currently 3 of these GMT 800 rigs lol. 2 '01 Suburban's and 1 05 Silverado Z71 5.3
Thicker oil wouldn't hurt but I would also check:
Oil pressure sensor
Oil pickup tube o ring seal
Oil Pump
Last 3 out 7 of the GMT 800's have been the oil pickup o ring seal, A B*tch of a job if you have a 4x4 model
Dave
In addition to Dave's comments, there is a screen beneath the oil pressure sensor that might be plugging in cold weather. Check you tube on how to pull the pressure sensor and screen. Takes a bit of effort.
Have had several and currently 3 of these GMT 800 rigs lol. 2 '01 Suburban's and 1 05 Silverado Z71 5.3
Thicker oil wouldn't hurt but I would also check:
Oil pressure sensor
Oil pickup tube o ring seal
Oil Pump
Last 3 out 7 of the GMT 800's have been the oil pickup o ring seal, A B*tch of a job if you have a 4x4 model
Dave
In addition to Dave's comments, there is a screen beneath the oil pressure sensor that might be plugging in cold weather. Check you tube on how to pull the pressure sensor and screen. Takes a bit of effort.
Verify with a shop oil pressure gauge. GM's oil pressure senders and gauge stepper motors from that time are a well documented failure point. I keep a spare sender on the shelf. Be careful with You Tube. There is one video where the guy used a pick to pull out the screen and destroyed it. There are tabs on the top of the screen you can grab with needle nose pliers and pull out with destroying it. It only plugs if you neglect the oil or use a torn Purolator filter that let crud circulate. Link to GM gauge problems. http://drspeedometer.com/ultimate-guide-to-gm-gauge-problems-and-how-to-repair
Originally Posted by SierraMan
Hey Guys … I have survived the cold winter (-10 to +15 deg F) and nursed my old Sierra (150,000 miles) through the worst of it. I did change the oil last fall to Castrol Syntec 5w20 full synthetic. However, as the temperatures dropped, I began to have difficulty in keeping the oil pressure up after a cold start. I would have to sit in the truck with my foot on the accelerator (keeping the RPM at around 1200 to 1500) in order to keep the oil pressure between 15 and 20 psi. As soon as the engine reached normal operating temperature everything was fine, and the engine maintained normal oil pressure at idle. We now have more moderate temperatures (25 t0 35 deg F),. but I still have to keep the RPM's up during a cold start. I am thinking of changing the oil to a 10W30 (or even a 15 W40) to attempt the get the low oil pressure problem under control. Does anyone have any experience with this type of problem? Any other suggestions?
What does the owners manual say for viscosity at temps you encounter?
Hey Guys … I have survived the cold winter (-10 to +15 deg F) and nursed my old Sierra (150,000 miles) through the worst of it. I did change the oil last fall to Castrol Syntec 5w20 full synthetic. However, as the temperatures dropped, I began to have difficulty in keeping the oil pressure up after a cold start. I would have to sit in the truck with my foot on the accelerator (keeping the RPM at around 1200 to 1500) in order to keep the oil pressure between 15 and 20 psi. As soon as the engine reached normal operating temperature everything was fine, and the engine maintained normal oil pressure at idle. We now have more moderate temperatures (25 t0 35 deg F),. but I still have to keep the RPM's up during a cold start. I am thinking of changing the oil to a 10W30 (or even a 15 W40) to attempt the get the low oil pressure problem under control. Does anyone have any experience with this type of problem? Any other suggestions?
What does the owners manual say for viscosity at temps you encounter?
I agree with checking with a mechanical gauge. I had a 2004 Silverado 5.3 and gauge would spike to the high side. I think they called step motors in the gauge and they go bad. Actually, anything above 0, 5 would still be OK, at idle is probably OK as long as you have normal pressure at road speed. Maybe change oil and filter and see what happens. 5W-30 like it should be and normal size filter.
Last edited:
The stepper motors in those gauge clusters are notoriously failure prone, I have replaced lots of them.
I always start with the cheap and easy stuff. I would start by seeing what the pressure really is with a reader, then with an actual gauge.
I always start with the cheap and easy stuff. I would start by seeing what the pressure really is with a reader, then with an actual gauge.
Last edited:
Ditch the 5w-20; it's too thin and not recommended. That's likely part or all of your problem.
The mfgr recommends 5W-30 or a 10W-30. And with that many miles on that engine, I'd be running a 10W-30 semi-syn or full-syn, even in the winter.
Good luck. And agree with many of the other sensor and gauge recommendations.
The mfgr recommends 5W-30 or a 10W-30. And with that many miles on that engine, I'd be running a 10W-30 semi-syn or full-syn, even in the winter.
Good luck. And agree with many of the other sensor and gauge recommendations.
Last edited:
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?
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?
For better starting in the winter to with a 0w30 not a 5w20. It probably didn't cause any damage, but better safe than sorry.
As far as idle goes...you can clean the IAC...I did it on my 2002 gmc donor truck (5.3 is going in my Caprice eventually) after sitting a few months it didn't want to idle when it got warmed up these weekend. The IAC looked very dirty inside and after spraying it out with throttle body cleaner it idled fine again. However these trucks don't seem to have a very high idle on cold starts. There is no adjustment either.
As far as idle goes...you can clean the IAC...I did it on my 2002 gmc donor truck (5.3 is going in my Caprice eventually) after sitting a few months it didn't want to idle when it got warmed up these weekend. The IAC looked very dirty inside and after spraying it out with throttle body cleaner it idled fine again. However these trucks don't seem to have a very high idle on cold starts. There is no adjustment either.
Originally Posted by GMguy84
Have had several and currently 3 of these GMT 800 rigs lol. 2 '01 Suburban's and 1 05 Silverado Z71 5.3
Thicker oil wouldn't hurt but I would also check:
Oil pressure sensor
Oil pickup tube o ring seal
Oil Pump
Last 3 out 7 of the GMT 800's have been the oil pickup o ring seal, A B*tch of a job if you have a 4x4 model
Dave
X2...on a lot of pre-AFM LS engines it is the pickup tube o ring.
I doubt the 5W20 is completely to blame, but it's not what I would use. I put 10W40 high mileage in most of the GMT800s at work, but most of the GMT800s at work have over 400K on them.
Have had several and currently 3 of these GMT 800 rigs lol. 2 '01 Suburban's and 1 05 Silverado Z71 5.3
Thicker oil wouldn't hurt but I would also check:
Oil pressure sensor
Oil pickup tube o ring seal
Oil Pump
Last 3 out 7 of the GMT 800's have been the oil pickup o ring seal, A B*tch of a job if you have a 4x4 model
Dave
X2...on a lot of pre-AFM LS engines it is the pickup tube o ring.
I doubt the 5W20 is completely to blame, but it's not what I would use. I put 10W40 high mileage in most of the GMT800s at work, but most of the GMT800s at work have over 400K on them.
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.
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.
Good catch clinebarger, no little screen under the pressure switch on that truck.
It's sounds like the oil pump pickup tube o-ring. I've changed 2 already In family vehicles.
- Status
