john_g_46

Has anyone else noticed this? I recently changed my pocket gauge display to include the numerical oil pressure indication. Every time I start the car, there is a 5-6 second delay before there is any indication of oil pressure other than "0". After the 5-6 seconds it very rapidly builds to 30-40 psi depending on outside temperature in less than a second.

Is this normal?

Is there really zero oil pressure for 5-6 seconds?

If so, the engine does 50-60 spins without oil pumping into any of the many journals in the engine upon each startup.

John

RonC7

The oil pump is a mechanical pump driven by the engine. 0 engine rpm = 0 pressure at engine start. No surprise there...

There will be residual oil in the bearings from the last engine run.

john_g_46

I agree, no surprise that initial pressure is zero. I had the oil pump in my hands out of my LS7 when I rebuilt the top half including cam replacement with my C6 Z06. I know how the pump works. Five to six seconds with no pressure just seems a little long to me.

John

YWZ08

I think it is just a gauge starting up thing. Mine does it too on the regular OP gauge. It seems to coincide with all the other gauges starting to come to life.

davepl

The LT4 has a variable displacement oil pump, but on LS motors where I've had a mechanical gauge the oil pressure comes up within 2 seconds tops, I'd say. I'm guessing that your gauge is just taking a while to produce a reading.

You could try turning the car ON first (press and hold start without the brake on for 10 seconds or so) and then starting it, that might reduce the "boot up" lag on the electronics. See if you get a faster response that way!

stevebz06

There was some discussion about oil pressure regarding an LS3 installed in a fifth gen Camaro in GrassRoots Mototsports magazine. What they said was the answer from a GM power train engineer was that oil pressure and temperature was not being directly measured but was being calculated using a lot of variables.

i would hazard a guess that this system is employed on the LT engines and this is what is causing the slow pressure response.

Why hy they chose to do it this way I don't know.

john_g_46

I noticed this morning that the Coolant Temperature and Oil Temperature come on immediately. But the Oil Pressure and the Battery Voltage both start at zero and both stay there for 5-6 seconds and then both do a count up thing. I'm really certain that the battery voltage doesn't start out at zero. ;-)

I'm satisfied that it's a gauge initialization thing.

John