Zero oil pressure - Debug thread
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,823
Likes: 43
From: East Aurora NY
Zero oil pressure - Debug thread
Last week I had zero oil pressure and did the following:
Replaced sensor
Tested sensor
Tested wiring to the best of my abilities
Replaced oil pump
Replaced oil filter + oil
Started it up today, zero oil pressure. Instead of being pissed beyond belief, lets debug this.
1 - Where can I get a cheap mechanical oil pressure setup for my car?
2 - What else can it be?
3 - Anyone have oil sensor wiring test instructions besides checking ground and 5v key on?
Before anyone asks, the pump was replaced with a Melling 10295, and aligned to crank.
Replaced sensor
Tested sensor
Tested wiring to the best of my abilities
Replaced oil pump
Replaced oil filter + oil
Started it up today, zero oil pressure. Instead of being pissed beyond belief, lets debug this.
1 - Where can I get a cheap mechanical oil pressure setup for my car?
2 - What else can it be?
3 - Anyone have oil sensor wiring test instructions besides checking ground and 5v key on?
Before anyone asks, the pump was replaced with a Melling 10295, and aligned to crank.
Last edited by nullpointer; Apr 25, 2015 at 05:10 PM.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Maybe a bad gauge? Did you check the oil pressure reading in the HUD?
Any auto parts store should have a mechanical oil pressure gauge. NAPA definitely will have them.
Any auto parts store should have a mechanical oil pressure gauge. NAPA definitely will have them.
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,823
Likes: 43
From: East Aurora NY
I had zero oil pressure, went through the list above, and still have zero oil pressure.
The DIC says low oil pressure so I didn't bother checking anything but the needle gauge.
I'll have to check if the common auto parts stores rents the oil pressure gauge, do they sandwich between the filter and block?
No codes either
The DIC says low oil pressure so I didn't bother checking anything but the needle gauge.
I'll have to check if the common auto parts stores rents the oil pressure gauge, do they sandwich between the filter and block?
No codes either
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,823
Likes: 43
From: East Aurora NY
It was packed during install to help with being primed, and started a few times. Ran for only a few seconds each time. With my original ported pump oil pressure could be seen almost immediately. I figured a few short starts would be enough to get some psi, but I also didn't want to risk my bearings being dry.
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,823
Likes: 43
From: East Aurora NY
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
you can get to the screen by just removing the lower pan but if you need to get the whole pickup tube out then the whole pan needs to come off... you can suspend the motor in the engine bay and remove the cradle/suspension and that will give you plenty of room
Le Mans Master
Joined: Feb 2012
Posts: 6,644
Likes: 479
From: OK
I'm just asking...not questioning your knowledge or input.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
There are also electrical oil pressure gauges, and these type use a sender and electrical connections.
AFAIK, there is no pressure gauge that has a connector that would be installed between the oil filter and the block.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
There is a second oil pressure port on the block that will fit a pressure gage. Its right off of the pump output, thats why GM doesn't use it for total after the oil filter pressure which is more meaningful..
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The second port is on a little forward on the block below the coolant temp sensor. When I had zero pressure, I used it and installed a mechanical gage and found out that I actually had oil presure. My five volt DC reff voltage was compromised.
I also found out that if you remove the filter and put your thumb over the pipe fitting that the oil filter screws on to, If you have pressure, you will NOT be able to stop the oil from flowing out when you crank the engine.
Check all of that out and see where you are.
Bill
I also found out that if you remove the filter and put your thumb over the pipe fitting that the oil filter screws on to, If you have pressure, you will NOT be able to stop the oil from flowing out when you crank the engine.
Check all of that out and see where you are.
Bill
Last edited by Bill Curlee; Apr 26, 2015 at 12:17 PM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Your oil pump is a positive displacement pump. If the vanes in the pump are properly seated and functioning and the O ring between the pump and the pick up tube is sealed, you dont need to prime the pump.
I have removed the upper & lower oil pan from an LS engine without removing the engine from the chassis. We also changed out the conncting rod bearings.
It is possible... Removing the lower pan will NOT allow you access to anything other than the pick up screen for the pump and access to the oil level sensor
Bill
I have removed the upper & lower oil pan from an LS engine without removing the engine from the chassis. We also changed out the conncting rod bearings.
It is possible... Removing the lower pan will NOT allow you access to anything other than the pick up screen for the pump and access to the oil level sensor
Bill
Le Mans Master
Joined: Feb 2012
Posts: 6,644
Likes: 479
From: OK
Let me make sure I'm getting this straight...
Your car is running fine no codes, normal operating pressures and temps... then all the sudden, BAM you have ZERO oil pressure.
First off then, I wouldn't have suspected oil pump... I would think that would have been a gradual or drop in pressure, not just BAM to Zero...
Unless there was a hole knocked in your oil pan, oil line broke, something to cause a dump of all of your oil...
My first thought would be OPS, second would have been gauges... wiring.
Of all the threads I've read so far, this one intrigues me more than any others just because it doesn't make sense to me...that the oil pump was the culprit. I'm looking forward to you getting your issue fixed and hoping you have no engine damage....
Your car is running fine no codes, normal operating pressures and temps... then all the sudden, BAM you have ZERO oil pressure.
First off then, I wouldn't have suspected oil pump... I would think that would have been a gradual or drop in pressure, not just BAM to Zero...
Unless there was a hole knocked in your oil pan, oil line broke, something to cause a dump of all of your oil...
My first thought would be OPS, second would have been gauges... wiring.
Of all the threads I've read so far, this one intrigues me more than any others just because it doesn't make sense to me...that the oil pump was the culprit. I'm looking forward to you getting your issue fixed and hoping you have no engine damage....
Team Owner
Joined: May 2001
Posts: 36,836
Likes: 244
From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Check for continuity between the EOP sensor connector and the PCM, for all three wires, to see if there is an open. Include a "wiggle test" of the wires/harness, etc when checking, to see if it's intermittent.
Tip: When checking, be very careful how you insert the DVOM probes into any of these connectors. A regular probe tip may deform/bend the connector contacts, etc. I prefer to use alligator test leads and clip them on to a paper clip inserted in the connector. Old school, but it works.
Edit: I just checked schematic in my '99 FSM and it shows the following (page 6-465):
1. Black (ground) goes to pin 63 on the blue PCM connector (C1)
2. Gray (5 volt ref) goes to pin 7 on the blue PCM connector (C1)
3. Tan/White (EOP sensor input) goes to pin 58 on the red PCM connector (C2)
HTH
Tip: When checking, be very careful how you insert the DVOM probes into any of these connectors. A regular probe tip may deform/bend the connector contacts, etc. I prefer to use alligator test leads and clip them on to a paper clip inserted in the connector. Old school, but it works.
Edit: I just checked schematic in my '99 FSM and it shows the following (page 6-465):
1. Black (ground) goes to pin 63 on the blue PCM connector (C1)
2. Gray (5 volt ref) goes to pin 7 on the blue PCM connector (C1)
3. Tan/White (EOP sensor input) goes to pin 58 on the red PCM connector (C2)
HTH
Last edited by LoneStarFRC; Apr 26, 2015 at 07:04 PM. Reason: add'l info
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
How does this happen? Is this another fairly common issues with the C5 that I haven't seen? If your using Mobil 1 and changing oil on regular intervals I can't imagine this happening, unless you have some other problem that is contributing to clogging the pickup screen...
I'm just asking...not questioning your knowledge or input.
I'm just asking...not questioning your knowledge or input.
... but if everything he has done checks out I don't know what else it could be
Le Mans Master
Joined: Feb 2012
Posts: 6,644
Likes: 479
From: OK
no it isn't anything I have personally seen and I agree that if oil changes are done properly it should not clog the screen unless some foreign material was introduced into the motor somehow... I have seen people leave rags in cylinder bores after doing a head gasket and other things along those lines, not saying the op did anything like this... but if everything he has done checks out I don't know what else it could be
... but if everything he has done checks out I don't know what else it could be