Random Oil pressure drops at idle
02-22-2024, 10:47 PM
#1
Random Oil pressure drops at idle
Hey everyone. So I am now chasing an issue after replacing my broken valve spring. After fixing a broken valve spring I was having weird oil pressure drops mostly at idle. Cruising was fine and normal. However on cold starts I would actually see the oil pressure climb up 5-8psi while cold at the same rpm. I figured with the lightly bent pushrod that maybe a lifter needed to pump back up. I did slap a new oil pressure unit in as well but the readings have been the same. So I figure that both sensors were good unless my cluster is acting up. After a day everything went back to normal and has been for the last month or so. Yesterday oil pressure at idle was 16psi all the way home. Normally its around 25-27psi depending on how hot the oil is. Been that way since I got the car at 84k miles. Its now at 155k. Cruising pressure was fine. But at 4k it seemed lower while I was testing.
Hopefully this is not the bottom end saying I am done. Oil level is at the full mark. Car has been running Amsoil since 50k miles. When the spring broke there were not pieces laying around. It looks like the spring broke in one spot and got jammed in itself. The cracked place looks like it could be put back together. So I don't think anything got into the pan.
Anybody got any ideas. Is there an easy place to drop in a mechanical gauge to check oil pressure on a ls6. Might try dropping the lower pan down to see if there is anything in there. Can you get the upper pan off or to the oil pickup with the engine in the car? Doubt a failed lifter would cause this. Maybe I am just unlucky and the engine is toast.
Hopefully this is not the bottom end saying I am done. Oil level is at the full mark. Car has been running Amsoil since 50k miles. When the spring broke there were not pieces laying around. It looks like the spring broke in one spot and got jammed in itself. The cracked place looks like it could be put back together. So I don't think anything got into the pan.
Anybody got any ideas. Is there an easy place to drop in a mechanical gauge to check oil pressure on a ls6. Might try dropping the lower pan down to see if there is anything in there. Can you get the upper pan off or to the oil pickup with the engine in the car? Doubt a failed lifter would cause this. Maybe I am just unlucky and the engine is toast.
02-26-2024, 01:10 AM
#2
Administrator
Member Since: Mar 2001
Location: In a parallel universe. Currently own 2014 Stingray Coupe.
Posts: 343,408
Received 19,427 Likes
on
14,043 Posts
C7 of the Year - Modified Finalist 2021
MO Events Coordinator
St. Jude Co-Organizer
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-'18-'19-
'20-'21-'22-'23-'24
NCM Sinkhole Donor
CI 5, 8 & 11 Veteran
Moved to C5 Tech for some advice.
02-26-2024, 09:17 AM
#3
Hey everyone. So I am now chasing an issue after replacing my broken valve spring. After fixing a broken valve spring I was having weird oil pressure drops mostly at idle. Cruising was fine and normal. However on cold starts I would actually see the oil pressure climb up 5-8psi while cold at the same rpm. I figured with the lightly bent pushrod that maybe a lifter needed to pump back up. I did slap a new oil pressure unit in as well but the readings have been the same. So I figure that both sensors were good unless my cluster is acting up. After a day everything went back to normal and has been for the last month or so. Yesterday oil pressure at idle was 16psi all the way home. Normally its around 25-27psi depending on how hot the oil is. Been that way since I got the car at 84k miles. Its now at 155k. Cruising pressure was fine. But at 4k it seemed lower while I was testing.
Hopefully this is not the bottom end saying I am done. Oil level is at the full mark. Car has been running Amsoil since 50k miles. When the spring broke there were not pieces laying around. It looks like the spring broke in one spot and got jammed in itself. The cracked place looks like it could be put back together. So I don't think anything got into the pan.
Anybody got any ideas. Is there an easy place to drop in a mechanical gauge to check oil pressure on a ls6. Might try dropping the lower pan down to see if there is anything in there. Can you get the upper pan off or to the oil pickup with the engine in the car? Doubt a failed lifter would cause this. Maybe I am just unlucky and the engine is toast.
Hopefully this is not the bottom end saying I am done. Oil level is at the full mark. Car has been running Amsoil since 50k miles. When the spring broke there were not pieces laying around. It looks like the spring broke in one spot and got jammed in itself. The cracked place looks like it could be put back together. So I don't think anything got into the pan.
Anybody got any ideas. Is there an easy place to drop in a mechanical gauge to check oil pressure on a ls6. Might try dropping the lower pan down to see if there is anything in there. Can you get the upper pan off or to the oil pickup with the engine in the car? Doubt a failed lifter would cause this. Maybe I am just unlucky and the engine is toast.
02-26-2024, 08:58 PM
#5
When in doubt, put a mechanical oil pressure gauge on the engine to see what's actually happening. There is access to the main oil galley, right after the pump, low on the LHS of the block. IIRC, the threads in the block are M16 x 1.25.
Frankly, there have been enough problems reported over the years about the OE oil pressure sender, that I wouldn't trust it any further that I could throw it. I'd say that there is a 98% likelihood that you have an oil pressure sender problem.
Having said that, since the engine was recently apart, another possibility is that some lint, swarf, or some other debris has found its way into the oil pressure relief valve area, periodically hanging it slightly open.
Frankly, there have been enough problems reported over the years about the OE oil pressure sender, that I wouldn't trust it any further that I could throw it. I'd say that there is a 98% likelihood that you have an oil pressure sender problem.
Having said that, since the engine was recently apart, another possibility is that some lint, swarf, or some other debris has found its way into the oil pressure relief valve area, periodically hanging it slightly open.
02-27-2024, 10:17 AM
#6
Team Owner
I'd get a new sensor from NAPA.
If you have a 2 piece oil pan, I'd drop the bottom cover to check for debris. Cutting the oil filter open would also be aa good idea.
If you have a 2 piece oil pan, I'd drop the bottom cover to check for debris. Cutting the oil filter open would also be aa good idea.
02-27-2024, 10:32 AM
#7
Yes these oil pressure sensors even the GM ones are trash.
Use a manual gauge to check it, if it's ok then replace the sender.
While there I suggest putting an extended oil pressure sender kit on the car so you don't have to pull the intake every time to replace the sender as they can and do fail that often, I had one that actually blew out and caused oil to go everywhere, I had to have the car towed home, this was prior to putting the extended kit on it. Now I keep a spare sender and 2 adjustable wrenches in the cubby in the trunk so I can replace it on the side of the road if it ever happens again....
Use a manual gauge to check it, if it's ok then replace the sender.
While there I suggest putting an extended oil pressure sender kit on the car so you don't have to pull the intake every time to replace the sender as they can and do fail that often, I had one that actually blew out and caused oil to go everywhere, I had to have the car towed home, this was prior to putting the extended kit on it. Now I keep a spare sender and 2 adjustable wrenches in the cubby in the trunk so I can replace it on the side of the road if it ever happens again....