WanaBquick

Hey guys I have a 99 gmc sierra and I just dropped in a rebuild 05 LQ9 from gm. I fired it up for the first time and my oil pressure ran about right for 5 minutes and then it spiked off the end of the guage which is over 80. I did change my gauge face so i might not have got my needles back on perfect. So does any one have some advice for me? Were should I start and what should I do? Thanks

08cheyennesc

iTrader: (2)

Turn the key all the way to run position but don't start the engine,the oil gauge should at 0 ,if it moves then the oil sensor is bad.
Engine off - YouTube

WanaBquick

Ya I did that and it stays right still at 0. So that means it something mechanical and not electrical???

AKlowriderZ71

iTrader: (22)

Sounds like a bad sending unit to me.

Silverad0 SS

Or the stepper motor could have went out

rjwz28

/\ These are dead on /\

I have had this happen to me before on my Cherokee and it sucks. It was a pretty straightforward replacement to DIY though; I did it in the parking lot at work because the sending unit actually ruptured and was pumping oil to the ground.

WanaBquick

But every time i start it, it sweeps from 0 all the way past 80. My best bet still is the sending unit?

rjwz28

It may be the stepper motor. Considering that the pressure was fine for the first few minutes, it would be pretty odd for something to fail and cause a pressure spike. I suppose it's possible.

Silverad0 SS

i bet its the stepper motor, my fuel an rpm gauge did this

WanaBquick

I forgot to say that I did change out my oil pressure sensor from my old 5.3 and put it on this new 6.0 because the electrical connector didnt fit the new 6.0 sensor. Would that have messed with it at all?