I've got a 2002 C5 Corvette with the LS1 and decided to do a rebuild and am getting 0 oil pressure.

- New Melling 10296 high volume oil pump
- New oil pressure sending unit
- New camshaft bearings, visually inspected and used a pick to verify oil holes were not blocked
- Crankshaft has been machined down, bearing sizes were adjusted and clearances were double checked and were within spec
- New camshaft retainer plate w/ gasket
- New LS7 style lifters
- New pushrods
- New filter
- All gaskets are new


After getting everything buttoned up and the engine back into the car, I hand primed the oil system via a garden sprayer pump through the priming port and the sensor was reading up to 27 psi while priming and the pushrods were flowing oil through. I decided to still crank the engine over with the starter (fuel pump off) and I was getting 0 psi after cranking for 3 15 second intervals.

I figured I had an issue with the O ring on the pickup tube, so I bought a new GM blue O-ring to replace the Melling black O ring and was still getting 0 psi after hand priming (sensor showed 26 psi during this step) and cranking the engine. I decided to pull the oil filter off and had someone else crank it and I visually confirmed that oil pump was indeed working and pushing fully liquid oil to the filter. Now I know that I do not have a pump suction issue and the O ring likely wasn't bad/installed incorrectly.

Knowing that I don't have a suction issue and oil was making it through the pushrods while hand priming, is it possible that using the starter isn't sufficient at providing enough oil pressure for the higher volume oil pump? Aren't these pumps more sensitive to RPM, hence not receiving enough RPM to produce adequate pressure? I would still expect some amount of pressure greater than 0 though.

Should I start the engine and check for pressure and immediately shut it off if I'm still at 0?

 

Did you try pulling the spark plugs out before rolling the engine over on the starter, that will give you more rpm to build some pressure. If it were me and my engine, I would go ahead and fire it up as long as you pre-prime it. If it doesn't show oil pressure in 10 seconds I'd kill it and look deeper into it.

 

In my opinion, using the starter to verify oil pressure isn't going to give you accurate results. Have you used a mechanical gauge to verify no oil pressure? I know it's a PITA to pull the balancer and timing cover again. That said, if you'll do that, again, Summit sells an external oil pump driver that you can spin with a drill motor. If you use that, be sure to use some grease or assembly lube on the crank and inside the tool, to avoid wearing or scoring the crank when it spins. Using that will tell you what you need to know. My .02.....

 

I’d Prefill the oil filter and fire it. Oil pressure will register in 3-4 seconds. If you don’t see needle start to move in 3-4, shut it off and verify that the new OPS is good. Plenty of bad sensors nowadays right out of the box. Gasp! I’d bet you’re fine however. Starter motor doesn’t spin it fast enough to get good pressure at 300ish rpm.