A3VETTE

iTrader: (2)

I have a LQ9 that hasnt had any oil pressure issues since it was built about 30k miles ago.

About 3 weeks ago, I did an oil change and the oil pressure was fine.

Last saturday I noticed the oil pressure kept dropping as I drove around (under 20 psi)

I parked the car for a week and started her up last night. Pressure was normal on cold start up (50-60 psi) then it settled to right at a normal 40 once the car warmed up at idle.

Driving around the pressure stayed around 35-40. I did a WOT pull, the pressure stayed at 40 when it usually jumps to 50-60. When I started to slow down, the presure started dropping slowly to 35 to 30 to 25 to 20.
It has never done this before.

Did another quick WOT pull and the pressure dropped some more under 10 and trigged a light and DIC low oil pressure message. The car hit a "wall" at 5000 rpms im guessing from the lifters not being able to pump back up fast enough.

So I shut it off and coasted to the side. Turned the car back on and pressure was at 18-20 and stayed around there no matter what RPM.
I didnt hear any funny noises coming from the engine (yet). Everything sounded normal.

The car has a high flow melling pump. It never has had a oil pressure issue before, just one problem with the sender but that was fixed long ago. This is time it definately seems pressure related and not electronics.

So today I changed out the oil filter (Pureone) just to make sure it didnt collapse or cause some sort of blockage. I put a Wix filter in and its still having the same issues. Oil is Mobil 10w30. Later on tonight I plan to cut open the pureone filter and check for particles.

But as of right now I have no idea what else to check for. Any help or opinions is appreciated.

69LT1Bird

iTrader: (1)

Put a mechanical gauge on and check the pressure.

CamaroSS22

iTrader: (1)

My question is that if you were worried about the pressure, why did you keep doing wot pulls? Just a question. I would change the oil, with a decent filter, and then put a mechanical guage on it.

A3VETTE

iTrader: (2)

I did 2 short pulls. I had changed the oil filter and and wanted to make sure it was an pressure problem and not a sensor problem. Oil is always Mobil and filters are Pureones, Wix or Mobil 1.

Bottom end is about to get refreshed with new bearings, rings and a oil pump.

sschoeffler

iTrader: (24)

30k miles is no reason to change bearings unless something is wrong. Hook up a mechanical oil pressure gauge and find out exactly what it is, not what some electric gauge is telling you. You can get a gauge for around 30 bucks at the parts store.