Oil pressure suddenly MIA?
Oil pressure suddenly MIA? The engine is a cammed LQ9 with 799 heads, it has a polished crank with new main/rod/cam bearings. New Mellings high performance oil pump (stock spring) as well.
Engine has about 250-300 miles on it and has had roughly 40# of oil pressure at warm idle and 80#+ at speed/rpm.
Today I was out doing its first WOT tuning pulls and about 5 minutes from the house I noticed very low oil pressure but couldn’t hear anything that would indicate loss of oil pressure and ETC’s were around 185.
So I decided to run it to the house and monitor.
Got her home and with a 2000 rpm blip of the throttle I see 20# and it settles back to like 5# at idle.
I can’t hear anything rattling knocking or complaining.
I have a Dakota digital dash with oil pressure sender (electric).
Thoughts? Could the sender have gone bad or might I have a real problem?
was gonna let her cool down and start her up latter hoping the sensor is heat soaked or something like that…
If that didn’t wok out I was gonna pull the valve covers and see if she is pumping oil by cranking her over a bit..
anything else to look at?
Engine has about 250-300 miles on it and has had roughly 40# of oil pressure at warm idle and 80#+ at speed/rpm.
Today I was out doing its first WOT tuning pulls and about 5 minutes from the house I noticed very low oil pressure but couldn’t hear anything that would indicate loss of oil pressure and ETC’s were around 185.
So I decided to run it to the house and monitor.
Got her home and with a 2000 rpm blip of the throttle I see 20# and it settles back to like 5# at idle.
I can’t hear anything rattling knocking or complaining.
I have a Dakota digital dash with oil pressure sender (electric).
Thoughts? Could the sender have gone bad or might I have a real problem?
was gonna let her cool down and start her up latter hoping the sensor is heat soaked or something like that…
If that didn’t wok out I was gonna pull the valve covers and see if she is pumping oil by cranking her over a bit..
anything else to look at?
TECH Resident
Joined: Apr 2007
Posts: 867
Likes: 218
From: Montgomery (Lake Conroe,) TX north of Houston
Last Tuesday I was driving my LS3 swapped Fox coupe for the first time in about 3 weeks. The build only has about 420 miles on it. Warm, 93F day and I've got the AC running. I've always felt that the oil pressure was a little low in this engine and with the higher, summertime temps, I was watching the oil pressure gauge. I pulled behind another car at a stop light and looked at my oil pressure on my Holley 12.3" Pro Dash. It was reading low and was bouncing around a bit. The reading was trending lower-going below 20 then 10 and all the way to 0 
!
I was stuck behind another car and there were cars behind me. I couldn't move and I'm not exaggerating, that signal light took all of 30 minutes to turn green!!! After it turned green, I immediately pulled into a gas station and shut the engine down. I called my wife and told her what happened and that I may have to tow the car home. I popped the hood and checked the oil level. It looked full. I then looked at the back of the engine where the oil pressure sender is and I could see my pressure sender wires. I put my hand on the wires and followed them down to the sender's connector. I pushed down on the connector and it move about 1/2" and I heard an audible "click" as the connector locked into place onto the sender! I was so relieved. The connector had come off and I had just reinstalled it.
Make sure your sender's wire connector is seated fully. If the connector is seated fully and the wires don't look damaged, then maybe your sender is bad. If you have a spare mechanical oil pressure gauge, you could always hook that up and see if you have oil pressure.
!I was stuck behind another car and there were cars behind me. I couldn't move and I'm not exaggerating, that signal light took all of 30 minutes to turn green!!! After it turned green, I immediately pulled into a gas station and shut the engine down. I called my wife and told her what happened and that I may have to tow the car home. I popped the hood and checked the oil level. It looked full. I then looked at the back of the engine where the oil pressure sender is and I could see my pressure sender wires. I put my hand on the wires and followed them down to the sender's connector. I pushed down on the connector and it move about 1/2" and I heard an audible "click" as the connector locked into place onto the sender! I was so relieved. The connector had come off and I had just reinstalled it.
Make sure your sender's wire connector is seated fully. If the connector is seated fully and the wires don't look damaged, then maybe your sender is bad. If you have a spare mechanical oil pressure gauge, you could always hook that up and see if you have oil pressure.
I waited till morning to fire her up, 40#'s at warm idle.
As a few of you know I was messing around with an electrical problem AND I also had to fix a vacuum leak (intake gaskets) so I was messing around back where the sending unit is.
I don't think it's the wiring but as I have recently demonstrated WTF do I know. Dakota Digital's oil pressure sender comes with wiring harness (3 wire) for the oil pressure sender so maybe there is a problem there. I'll check the harness and clips what I get out there.
My under hood temps are really high, my IAT heat soaked in 10 minutes and read 130ish early in this build (moved the IAT out of the ebay since then) so heat could be messing with the sensor as well, there is negative area for air flow in the engine bay as it is, never mind at the back of the engine.
Might send a quick note to Dakota to hear what they have to say. Here is the unit I have.
https://www.summitracing.com/parts/dak-sen-03-8
In the mean time I'm gonna prep for another WOT tuning drive. I'll pay more attention to the oil pressure and see if I can ignore my panic instinct in the event I lose pressure again...
As a few of you know I was messing around with an electrical problem AND I also had to fix a vacuum leak (intake gaskets) so I was messing around back where the sending unit is.
I don't think it's the wiring but as I have recently demonstrated WTF do I know. Dakota Digital's oil pressure sender comes with wiring harness (3 wire) for the oil pressure sender so maybe there is a problem there. I'll check the harness and clips what I get out there.
My under hood temps are really high, my IAT heat soaked in 10 minutes and read 130ish early in this build (moved the IAT out of the ebay since then) so heat could be messing with the sensor as well, there is negative area for air flow in the engine bay as it is, never mind at the back of the engine.
Might send a quick note to Dakota to hear what they have to say. Here is the unit I have.
https://www.summitracing.com/parts/dak-sen-03-8
In the mean time I'm gonna prep for another WOT tuning drive. I'll pay more attention to the oil pressure and see if I can ignore my panic instinct in the event I lose pressure again...
Actually the gauge and sending unit appear to be in working order
Whats not in working order is my “Iron LS2” build!
While checking everything over I had her idle for minute or two to warm up and I watched the oil pressure drop. I then pulled a VC and cranked her over, no oil. So I started her, a little oil but not what it needs to be. And I am hearing some noises now as well.
not cool, I’ll start the process of getting it pulled tonight.
Whats not in working order is my “Iron LS2” build!
While checking everything over I had her idle for minute or two to warm up and I watched the oil pressure drop. I then pulled a VC and cranked her over, no oil. So I started her, a little oil but not what it needs to be. And I am hearing some noises now as well.
not cool, I’ll start the process of getting it pulled tonight.
