I have reviewed numerous other postings here over the past week and have considered lots of postings regarding oil pressure issues, but still come up empty on WHY not getting any Oil Pressure when cranking the motor after several attempts! My analog pressure gauge works, confirmed lots of oil in the pan, filter is full, even confirmed pump moving some oil to filter housing; BUT not getting any oil pressure when cranking motor. The motor has not been restarted since upgrades were completed six motors ago. Checked al the normal or regular issues with revolve around the oil pick up "O" ring and other issues.

OK so here's some additional facts: 2004 LS6 used motor taken from CTS-V; only 30,000 miles from damaged vehicle. Upgrades and replacement parts were installed which included: new oil pump, new timing chain and gears, camshaft, tie bar lifters, hardened push roads, heads professionally re-done; ARP bolts, replaced oil pan, pickup.

Replaced Oil pan with Corvette "Bat" pan including the pickup; New Mellings 10296 Oil pump; also added analog 12V oil pressure sensor to the oil by-pass port located above oil filter. It should also be noted this motor is installed into a mid-engine project car and for purposes of the reassembly of the motor after the upgrades we used a Haynes GM manual for the Camaro LS1 engine, even though mine is the 2004 LS6 and running an aftermarket ECU system.

DOES the motor really need to be started to try and build up pressure (ie. 20-30 psi) ? If so then how long would you run the motor "waiting" for oil pressure to build up ? Really appreciate replies and so knowledgeable thoughts on next steps to address this problem without risk of damaging a rather expensive motor. Cheers and thank you, Allan

 

There are lots of threads on the subject, Many people can't get pressure until the engine is actually running. You could prime it first. Lots of threads on that also. Garden sprayer for a primer seems like a cost effective idea. https://ls1tech.com/forums/generatio...l-priming.html

 

It may take 20 seconds or so of cranking to read a change in pressure. I'd rather achieve pressure by cranking, rather than running the engine, being that cranking is 300 rpm, as opposed to 1200.
I've never had to prime, or pack the pump in Vaseline or grease, to achieve pressure.
Did the rebuilder replace the oil galley plug/dumbbell?
Is the O-ring properly mounted on the filler tube? Some (including myself ) have incorrectly placed the O-ring all the way on the filler tube, rather than placed correctly before the filler tube flare.

The correct way...

 

Appreciate the comments; engine builder actually only did the heads, personally I handled the other install items over six months ago. I did check out lots of other threads, but still not locating the problem of no oil pressure when cranking. Any thoughts if the location of the analog oil pressure sensor on the by-pass housing is acceptable approach? Don't remember if the O ring sat on the middle section or above the flare? If above the flare, would that be the problem for low suction or no suction? Welcome others thoughts, thanks

 

Are you cranking with spark plugs in? You get more rpms if you remove the plugs. If you read some of the other threads on the topic some people just can't get pressure until the motor is fired but never had a problem afterward.

 

Cranking with Ign/Fuel disconnected, spark plugs out ! Not started yet a little concerned with no oil pressure; as well may take some time to start with aftermarket ECU and configuring the start up settings. Thanks

 

dont start it before you get pressure! i had similair issues with my truck after doing the cam swap. with your plugs out you should be able to build around 20-30lbs. double check your o ring

 

Cranking it with no pressure is doing as much damage as starting it with no pressure for 10 sec.

The proper way is to pre lube the engine.

Either pre lube it or just start it.

 

I'm interested inthe O-ring question also. I can't rmember now how I placed it.

 

Keep in mind the oil pump on these and other modern engines are NOT immersed in the oil in the pan sump. Sometimes it takes some decent crank speed to get suction up enough to start drawing oil.

You could open the oil galley plug on the front left of the block and dump in some oil-thereby "priming" the pump as you would a de-watering pump.

This is my freshly built engine. It did take a few seconds at first to get pressure up.

 

When the o-ring is mounted all the way on, beyond the flare, it is the metal flare which pushes against the pump, rather than the o-ring. While there is some measure of rubber touching the pump, it probably isn't enough of a seal.

 

The o ring is not subject to pressure.

 

Yes, thanks for the correction Gray, but don't remove your o-ring.

 

The o ring is the suction side..

Screw the o ring I use a 2 bolt flange with a flat gasket. Never any leaks

Tim

 

O-ring works for me. Never any leaks here, either.

 

The oil cooler ports above the oil filter haven't been blocked off with a flat plate have they?
I ask because a local swapped an LQ4 that had a factory cooler and then couldn't figure out why it didn't make pressure. It needed the GM oil cooler delete plate that is bulged out instead of the homemade flat blockoff plate.

 

Appreciate the comments and hopeful to confirm the problem and then solved soon. The actual bulged bypass is in place; however I did relocate the oil temperature sensor and replaced with stainless fitting (Tee) and added analog 12V oil pressure sensor to the oil by-pass port located above oil filter. Still open to others comments and those that also experienced similar issues when cranking, no oil pressure is present.

 

Sometimes these engines are a bitch to prime....if your comfy your O-ring is perfect and you have assembly lube on all the important bearing surfaces you could honestly fire it up.....you should have pressure in 2-3 seconds. If 5 seconds pass I would kill the engine and trouble shoot a little.

Another trick I have used on the dyno is to actually pressurize the crankcase with regulated compressed air (8-10 PSI) while your cranking the engine with no plugs and a fresh battery. The pressurized crankcase actually helps push the oil into the oil pump and helps it prime right away. You have to block off all areas that air can escape on the valve covers to be able to build this pressure and it can be monitored with a pressure/vacuum gauge available at any parts store.

Makes sense right?.....your putting pressure across the entire top of the oil level in the sump therefore its pushed up the pick up and into the oil pump....it really helps the suction from the slow turning oil pump get oil to it and prime the system.

Hope this helps

-Tony

 

I just recently had to do the same thing with my engine, i cranked it without plugs, fuel and spark for about 30-40 seconds total and no pressure. I over filled it (7 qts in a 5 qt pan) and the higher oil level will naturally make its way farther up the pickup tube.

 

And it actually worked too