fruitsalad

iTrader: (5)

As soon as I started my car (2000 SS M6 with 53,000 miles) this morning it sounded kind of wrong, so while it was warming up I went over and listened to the engine. It sounded fine with my head in the engine bay, both idling and when I cracked the throttle a couple times. It had been making a kind of knocking sound, (not really a rod knock sound) but that went away and transitioned into more of a slight rubbing kind of noise that would only be noticeable to me above the normal engine noise. This was only audible from the cockpit.

I got back in the car thinking it must have been nothing, just the typical cold start piston slap/valvetrain noise and had just started backing out of the driveway when I noticed the oil pressure gauge was reading below 0 like it wasn't even on. I shut it down immediately and checked the oil 3 times. A little low, but still in the operating range. No oil leaking out on the driveway. It has always consumed a little oil in the past as LS1s do, and it was due for an oil change anyway. Oil was a little dark (to be expected when it's due to be changed) but no metallic sheen and no fragments of anything, at least not on the dipstick.

I started the car one more time hoping it was just a gauge fault or something. Still no pressure. Shut it down immediately again. This time when I shut it down, the gauge crept up to about 20 psi after the car was off.

I have no idea what it could be other than either a bad rod bearing or a clogged oil pump. What really stumps me is there were no warning signs whatsoever of this. When I parked it the night before, my oil pressure was fine, 40 psi idle, 45-60 psi on the throttle, building with rpm. I did always get the typical piston slap noise on cold starts, but it would always go away as it warmed up. Nothing else is wrong with the car other than a broken parking brake cable.

Any ideas?

Ls1Diablo

check your oil pressure switch

trans_am7935

iTrader: (15)

My brother had this same issue with his LQ4 equipped truck, it turned out to be the oil pump o-ring. The "ticking" noise could be air being sucked into the pump, can you post a video?

Does it do it on cold starts or just hot ones?
Does oil pressure increase at all with rpm's?
Does the "tick" go away with rpm's?

fruitsalad

iTrader: (5)

I'll try to get a video later when I'm back home, although I'm hesitant to run it anymore if it's not getting oil.

When you say does it do it on cold starts, I'm assuming you're referring to the "piston slap" noise? It would only make that noise on cold starts. This oil pressure thing or anything like it has never happened to me before.

The pressure would not increase with rpms. For the short time I had it on I revved it up to 2k, then 3k and no change, the needle was still pinned to the bottom of the gauge like it wasn't on at all. The sound kind of went away with rpms... I couldn't hear it as well when I revved it up so it definitely wasn't getting louder.

Then after I shut the engine off the gauge would slowly move up and stop at the 20 psi line.

I thought about this, but hearing that noise makes me think it's mechanical related, like the pump or a bearing.

fruitsalad

iTrader: (5)

Bump for diagnosis. Almost positive it's the oil pump now but not sure.

Whatever it is it happened overnight while the car was off, so I'm guessing pump o-ring contracted in the cold and got pinched.