Zero Oil Pressure -- Why
Thread Starter
Safety Car
Joined: Apr 2004
Posts: 3,996
Likes: 77
From: Louisville KY
Zero Oil Pressure -- Why
The last three time I have started the vette it shows zero oil pressure for 3 or 4 seconds, the DIC then says low oil pressure. It does this with the oil hot or cold. The gauge then jumps up to the normal 40ish range. When driving it goes up and down with the RPM's just as usual.
The oil level is at the exact mark. It is a AC Delco filter. The oil life is at 72%. It has Mobile1 5-30 oil in it. It has 34K. There are no mods. There are no codes.
When it is at zero for those few seconds there are no abnormal engine sounds. My 68 Camaro 327 makes noise for 4 or 5 seconds as the oil pressure comes up after an oil change. The vette makes no sounds like this. The engine is silky smooth at idle.
So is it the oil pressure sending unit or is it the oil pump starting to go bad? I have extended warranty so it will go to the dealer early next week. I would just like you guys opinion. Thanks!!
The oil level is at the exact mark. It is a AC Delco filter. The oil life is at 72%. It has Mobile1 5-30 oil in it. It has 34K. There are no mods. There are no codes.
When it is at zero for those few seconds there are no abnormal engine sounds. My 68 Camaro 327 makes noise for 4 or 5 seconds as the oil pressure comes up after an oil change. The vette makes no sounds like this. The engine is silky smooth at idle.
So is it the oil pressure sending unit or is it the oil pump starting to go bad? I have extended warranty so it will go to the dealer early next week. I would just like you guys opinion. Thanks!!
Last edited by Jim2003; Jul 21, 2007 at 11:09 AM. Reason: Added info.
Melting Slicks
Joined: Jul 2006
Posts: 2,088
Likes: 2
From: tampa florida
Usually when the sending unit goes bad it reads to the maximum pressure, not zero. But there may be instances where it does what you are describing. However I haven't seen it (mine went bad at read full pressure) or read about it registering zero and being bad yet.
There is usually a one or two second delay while the pump builds pressure and for the sensor to read it properly, but I have not seen it trigger the warnings so I would be concerned.
I have a high volume melling pump and it takes at least a second to begin building the pressure but I get no warnings. So I would be concerned the pump may be failing.
Glad you have the warranty. Stay on top of the dealer you are taking it to, many horror stories when you get a dealer involved. Post back what the outcome is.
I wish you the best of luck
Brad
There is usually a one or two second delay while the pump builds pressure and for the sensor to read it properly, but I have not seen it trigger the warnings so I would be concerned.
I have a high volume melling pump and it takes at least a second to begin building the pressure but I get no warnings. So I would be concerned the pump may be failing.
Glad you have the warranty. Stay on top of the dealer you are taking it to, many horror stories when you get a dealer involved. Post back what the outcome is.
I wish you the best of luck
Brad
Melting Slicks
Joined: Jul 2006
Posts: 2,088
Likes: 2
From: tampa florida
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
I think you need a mechanical oil pressure test which is done with a dealer tool that interfaces the oil filter. Its worth the $80 to find out if you have a failing oil pump or not, BEFORE you possibly hurt the engine should the pump actually be failing.
Last edited by dgrant3830; Jul 21, 2007 at 04:17 PM.
Instructor
Joined: Jul 2005
Posts: 231
Likes: 0
From: Hinckley, Ohio
My pump just went out on me (actually, the pressure relief valve stuck open). I was at an HPDE and while on the track I know I had oil pressure as I was looking at the pressure gauge. After the session, I shut down for lunch and then came back to fire it up - 0 oil pressure on the gauge and DIC!! 
I shut down immediately and checked the oil level. Everything looked fine so I started it back up and still no pressure. Thinking maybe it was a bad sending unit, I let it run for about 10 seconds and then the valve train started making noise. Shut it down and got a flat bed ride home.
Once home I pulled the oil filter and then cranked the engine. Not a drop came out, which told me there definitely was an issue with the oil pump or oil pick up.
After tearing out the oil pump I decided to open it up to verify if it was in fact the pressure relief valve. Sure enough, it was stuck in the open position. After some research, it seems that '97-‘00 LS1 oil pumps were prone to this problem.
I’m putting in a Melling oil pump (and cam while I’m in there).
I shut down immediately and checked the oil level. Everything looked fine so I started it back up and still no pressure. Thinking maybe it was a bad sending unit, I let it run for about 10 seconds and then the valve train started making noise. Shut it down and got a flat bed ride home.
Once home I pulled the oil filter and then cranked the engine. Not a drop came out, which told me there definitely was an issue with the oil pump or oil pick up.
After tearing out the oil pump I decided to open it up to verify if it was in fact the pressure relief valve. Sure enough, it was stuck in the open position. After some research, it seems that '97-‘00 LS1 oil pumps were prone to this problem.
I’m putting in a Melling oil pump (and cam while I’m in there).
Last edited by NigelTufnel; Jul 25, 2007 at 08:46 AM.
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
My pump just went out on me (actually, the pressure relief valve stuck open). I was at an HPDE and while on the track I know I had oil pressure as I was looking at the pressure gauge. After the session, I shut down for lunch and then came back to fire it up - 0 oil pressure on the gauge and DIC!!
I shut down immediately and checked the oil level. Everything looked fine so I started it back up and still no pressure. Thinking maybe it was a bad sending unit, I let it run for about 10 seconds and then the valve train started making noise. Shut it down and got a flat bed ride home.
Once home I pulled the oil filter and then cranked the engine. Not a drop came out, which told me there definitely was an issue with the oil pump or oil pick up.
After tearing out the oil pump I decided to open it up to verify if it was in fact the pressure relief valve. Sure enough, it was stuck in the open position. After some research, it seems that '97-‘00 LS1 oil pumps were prone to this problem.
I’m putting in a Melling oil pump (and cam while I’m in there).
I shut down immediately and checked the oil level. Everything looked fine so I started it back up and still no pressure. Thinking maybe it was a bad sending unit, I let it run for about 10 seconds and then the valve train started making noise. Shut it down and got a flat bed ride home.
Once home I pulled the oil filter and then cranked the engine. Not a drop came out, which told me there definitely was an issue with the oil pump or oil pick up.
After tearing out the oil pump I decided to open it up to verify if it was in fact the pressure relief valve. Sure enough, it was stuck in the open position. After some research, it seems that '97-‘00 LS1 oil pumps were prone to this problem.
I’m putting in a Melling oil pump (and cam while I’m in there).
Have to say that by far the most reports here are bad sensors
Just goes to show you can never be certain
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