Low oil pressure
11-11-2016, 07:10 PM
#1
Low oil pressure Hello, I took my c5 out for a ride and was monitoring oil pressure. cold it has about 45 psi, but after driving for around 20- 30 minutes, it drops to 15-20psi, It even hit 13 psi at one point so I pulled off so I could let it cool down. fired it back up and 35 psi, so I carefully limped it home.
I just changed oil and filter a few weeks ago and it is at the proper level, so I'm beginning to suspect either the oil pump or the pick up tube o-ring has deteriorated. I've replaced a bunch of oil pumps on other larger ls vehicles but never a vette.
the car recently had a cam installed by a preformance shop so it must of come off to swap cams.
I wonder if they seated the oring correctly, but I think I remember hearing something about an oil pump recall on the older c5s, mines a 98 so that's possible.
if any one has any recconendations/ ideas to what's going on, that would be appreciated.
I forgot to mention that the pressure does rise up to 55psi warm while on throttle. cam is pretty lopey and it idles at 900 RPM so that might take into account. and oil sending unit is brand new.
thanks
I just changed oil and filter a few weeks ago and it is at the proper level, so I'm beginning to suspect either the oil pump or the pick up tube o-ring has deteriorated. I've replaced a bunch of oil pumps on other larger ls vehicles but never a vette.
the car recently had a cam installed by a preformance shop so it must of come off to swap cams.
I wonder if they seated the oring correctly, but I think I remember hearing something about an oil pump recall on the older c5s, mines a 98 so that's possible.
if any one has any recconendations/ ideas to what's going on, that would be appreciated.
I forgot to mention that the pressure does rise up to 55psi warm while on throttle. cam is pretty lopey and it idles at 900 RPM so that might take into account. and oil sending unit is brand new.
thanks
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11-14-2016, 02:12 AM
#8
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There was no recall on oil pumps for any year. The 2001+ engines got an LS6 pump, which was an improvement. The older LS1 pumps (2000 and before) sometimes had instances of the pressure relief valve sticking open causing a zero pressure condition. This is relatively rare and usually happened at very low mileage, more of a random factory defect than age/wear related.
At 233k, I would expect lower-than-average pressure if the engine has not received a rebuild. But if this condition was a sudden change, rather than slow onset, then the OPSU might be failing/faulty (especially if the new one you have is not a GM replacement.) The fact it recently had a cam swap adds another variable, specifically the pickup tube O-ring you mentioned above. That's also a very likely reason in this case.
5w30 M1 is not something I would use even on a fresh, low mile LS - and especially not for yours. I'd recommend M1 0W40 if you want to stick with Mobil 1.
Lastly, I wouldn't be too worried if pressure is still going up to proper levels as rpms rise. 15-20psi at hot idle, even with a 900rpm idle speed, isn't too bad at 233k miles and M1 5w30 grade oil (unless of course this was a sudden change, in which case I would again suspect the OPSU or O-ring issues related to the recent cam swap.)
At 233k, I would expect lower-than-average pressure if the engine has not received a rebuild. But if this condition was a sudden change, rather than slow onset, then the OPSU might be failing/faulty (especially if the new one you have is not a GM replacement.) The fact it recently had a cam swap adds another variable, specifically the pickup tube O-ring you mentioned above. That's also a very likely reason in this case.
5w30 M1 is not something I would use even on a fresh, low mile LS - and especially not for yours. I'd recommend M1 0W40 if you want to stick with Mobil 1.
Lastly, I wouldn't be too worried if pressure is still going up to proper levels as rpms rise. 15-20psi at hot idle, even with a 900rpm idle speed, isn't too bad at 233k miles and M1 5w30 grade oil (unless of course this was a sudden change, in which case I would again suspect the OPSU or O-ring issues related to the recent cam swap.)
11-14-2016, 07:45 AM
#10
Does the oil pressure still increase with rpm? That would be my main concern.
Also, you could try running a little thicker oil. 5-30 Mobil one is like water. Move up to a 40weight synthetic or even 15w-50 Mobil one. There have been oil analysis reports done on a stock LS1 with 20w-50 VR1 synthetic and the results were less wear then with 5w-30. Now I am not saying to run a oil that thick as it is not necessary in most cases and will cost a little power, but my point is it will not hurt anything to move up to a thicker blend.
Also, you could try running a little thicker oil. 5-30 Mobil one is like water. Move up to a 40weight synthetic or even 15w-50 Mobil one. There have been oil analysis reports done on a stock LS1 with 20w-50 VR1 synthetic and the results were less wear then with 5w-30. Now I am not saying to run a oil that thick as it is not necessary in most cases and will cost a little power, but my point is it will not hurt anything to move up to a thicker blend.
11-14-2016, 12:13 PM
#11
Does the oil pressure still increase with rpm? That would be my main concern.
Also, you could try running a little thicker oil. 5-30 Mobil one is like water. Move up to a 40weight synthetic or even 15w-50 Mobil one. There have been oil analysis reports done on a stock LS1 with 20w-50 VR1 synthetic and the results were less wear then with 5w-30. Now I am not saying to run a oil that thick as it is not necessary in most cases and will cost a little power, but my point is it will not hurt anything to move up to a thicker blend.
Also, you could try running a little thicker oil. 5-30 Mobil one is like water. Move up to a 40weight synthetic or even 15w-50 Mobil one. There have been oil analysis reports done on a stock LS1 with 20w-50 VR1 synthetic and the results were less wear then with 5w-30. Now I am not saying to run a oil that thick as it is not necessary in most cases and will cost a little power, but my point is it will not hurt anything to move up to a thicker blend.
11-14-2016, 12:16 PM
#12
There was no recall on oil pumps for any year. The 2001+ engines got an LS6 pump, which was an improvement. The older LS1 pumps (2000 and before) sometimes had instances of the pressure relief valve sticking open causing a zero pressure condition. This is relatively rare and usually happened at very low mileage, more of a random factory defect than age/wear related.
At 233k, I would expect lower-than-average pressure if the engine has not received a rebuild. But if this condition was a sudden change, rather than slow onset, then the OPSU might be failing/faulty (especially if the new one you have is not a GM replacement.) The fact it recently had a cam swap adds another variable, specifically the pickup tube O-ring you mentioned above. That's also a very likely reason in this case.
5w30 M1 is not something I would use even on a fresh, low mile LS - and especially not for yours. I'd recommend M1 0W40 if you want to stick with Mobil 1.
Lastly, I wouldn't be too worried if pressure is still going up to proper levels as rpms rise. 15-20psi at hot idle, even with a 900rpm idle speed, isn't too bad at 233k miles and M1 5w30 grade oil (unless of course this was a sudden change, in which case I would again suspect the OPSU or O-ring issues related to the recent cam swap.)
At 233k, I would expect lower-than-average pressure if the engine has not received a rebuild. But if this condition was a sudden change, rather than slow onset, then the OPSU might be failing/faulty (especially if the new one you have is not a GM replacement.) The fact it recently had a cam swap adds another variable, specifically the pickup tube O-ring you mentioned above. That's also a very likely reason in this case.
5w30 M1 is not something I would use even on a fresh, low mile LS - and especially not for yours. I'd recommend M1 0W40 if you want to stick with Mobil 1.
Lastly, I wouldn't be too worried if pressure is still going up to proper levels as rpms rise. 15-20psi at hot idle, even with a 900rpm idle speed, isn't too bad at 233k miles and M1 5w30 grade oil (unless of course this was a sudden change, in which case I would again suspect the OPSU or O-ring issues related to the recent cam swap.)
11-14-2016, 12:34 PM
#13
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*shrug* mine is barely at 20psi on a 78k mile motor... As long as psi rises with rpm's I wouldn't worry about it. Old 350's, 400's, and 455's ran forever on 2-3psi @ idle. I think the internet has gone to the 10psi per 1000 rpm as a general rule and that couldn't be further from the truth of what your engine actually needs to operate properly.
Bottom line, I wouldn't worry about it unless you are actually "losing" oil pressure. Cruising on the highway your pressure will go down, this is normal. Again, do a couple decent WOT passes and watch your oil pressure, if it's rising don't mess with it.
As already mentioned, different weight oils will register different for psi on your gauge, this goes for synthetic vs non as well.
As some previous guys have mentioned... If your oil pressure is rising with rpm's your fine. Bottom line, it sounds like your fine.
Bottom line, I wouldn't worry about it unless you are actually "losing" oil pressure. Cruising on the highway your pressure will go down, this is normal. Again, do a couple decent WOT passes and watch your oil pressure, if it's rising don't mess with it.
As already mentioned, different weight oils will register different for psi on your gauge, this goes for synthetic vs non as well.
As some previous guys have mentioned... If your oil pressure is rising with rpm's your fine. Bottom line, it sounds like your fine.
Last edited by silvershark; 11-14-2016 at 12:59 PM.
11-14-2016, 03:47 PM
#15
*shrug* mine is barely at 20psi on a 78k mile motor... As long as psi rises with rpm's I wouldn't worry about it. Old 350's, 400's, and 455's ran forever on 2-3psi @ idle. I think the internet has gone to the 10psi per 1000 rpm as a general rule and that couldn't be further from the truth of what your engine actually needs to operate properly.
Bottom line, I wouldn't worry about it unless you are actually "losing" oil pressure. Cruising on the highway your pressure will go down, this is normal. Again, do a couple decent WOT passes and watch your oil pressure, if it's rising don't mess with it.
As already mentioned, different weight oils will register different for psi on your gauge, this goes for synthetic vs non as well.
As some previous guys have mentioned... If your oil pressure is rising with rpm's your fine. Bottom line, it sounds like your fine.
Bottom line, I wouldn't worry about it unless you are actually "losing" oil pressure. Cruising on the highway your pressure will go down, this is normal. Again, do a couple decent WOT passes and watch your oil pressure, if it's rising don't mess with it.
As already mentioned, different weight oils will register different for psi on your gauge, this goes for synthetic vs non as well.
As some previous guys have mentioned... If your oil pressure is rising with rpm's your fine. Bottom line, it sounds like your fine.
11-15-2016, 09:45 AM
#16
If you are at 15psi at idle and If you turn the car off and fire it back up and immediately reads higher (35 psi) then I would bet the OPSU is failing. Oil pressure isn't going to just change like that from shutting off and turning back on the car.