No Oil Pressure While Cranking 2020 GM 6.0 V8

[garageman402]

Is this normal? It's been like this since new. After an OC I flood clear crank to prime the system & no matter how long I crank (20 sec) no pressure seems to build. When it fires, it takes a few seconds for pressure to register, & when it does, it's normal.

I can fill the crankcase, fill the filter, then crank for 20 sec & oil level unchanged. If I start it, then let it settle, the oil level is lower. So oil is getting pumped when running, but not when cranking.

I know the pump is now around the crankshaft, it's not submerged as in older designs, would this affect the prime?

 

[PontiacHO]

Starter doesn’t spin an engine fast enough to build pressure that will show on your gauge but oil is flowing.

 

[martinq]

Wow! That is disturbing.

I've never tried this myself but I'm extremely curious what the cause is. Electronic controlled pump or pressure relief?

To clarify, I've done this countless times in the past with older equipment (pre 2012) and have always had oil pressure while cranking after an oil change or rebuild.

 

[kschachn]

Registering where?

 

[Donald]

Is this normal? It's been like this since new. After an OC I flood clear crank to prime the system & no matter how long I crank (20 sec) no pressure seems to build. When it fires, it takes a few seconds for pressure to register, & when it does, it's normal.

I can fill the crankcase, fill the filter, then crank for 20 sec & oil level unchanged. If I start it, then let it settle, the oil level is lower. So oil is getting pumped when running, but not when cranking.

I know the pump is now around the crankshaft, it's not submerged as in older designs, would this affect the prime?

Are you looking at a mechanical gauge?

 

[ls1mike]

Does it come right up and when running? Never seen that question asked about an LS engine.
I assume you are looking at the dash?

 

[burbguy82]

Why are you flood clearing after an OC? I think this is your issue. Do it like the rest of the world, change the oil, start, wait for pressure to build, stop, wait 5 minutes and check. Done. Prefill the filter BTW

6.0? 2020? is this a commercial van?

 

[ls1mike]

I mean all of my LS stuff is like that.

 

[garageman402]

Registering where?

Are you looking at a mechanical gauge?

On the dash gauge. Yes I'm aware the gauge may not function in start mode, but there's no pressure when starting even after trying to prime.

 

[garageman402]

I mean all of my LS stuff is like that.

So it's pretty normal? No oil pumped at cranking RPM?

 

[garageman402]

Why are you flood clearing after an OC? I think this is your issue. Do it like the rest of the world, change the oil, start, wait for pressure to build, stop, wait 5 minutes and check. Done. Prefill the filter BTW

6.0? 2020? is this a commercial van?

Yes a Chevy Express 4500

Yes filter is prefilled, see my original post

 

[Chris142]

Good thing you never had a 60's-70's Buick that would lose oil pressure when you took the filter off .

 

[burbguy82]

Yes a Chevy Express 4500

Yes filter is prefilled, see my original post

Ok, I would say a non issue then, IMO.

If you are worried about after OC oil change, just change it as close to after a trip as possible. At that point there is still plenty of oil coating to protect the engine.

 

[walterjay]

Maybe the oil pressure sensor is not that sensitive at startup. I wouldn't be too concerned about it though.

 

[ls1mike]

So it's pretty normal? No oil pumped at cranking RPM?

It is to me. The Caprice is over 100,000 miles now and after an oil change it takes a few seconds to see anything on the dash. Same with the Corvette LS2 and same with my kids 6.0 truck. The old WS6 was always slow to respond. Like 5 seconds but I think that was the sending unit.

 

[Snagglefoot]

The oil pressure sensor is at the top of the engine above the valley cover. You won’t see oil pressure until the engine is idling at 600 rpm and the galleries have filled with oil and even then you won’t see it for 3-4 seconds depending on oil temp. Everything looks normal.

 

[The_Eric]

It's a feature not a bug. The gauges do a min/max sweep after starting, right? You've got oil pressure, the computer just isn't on a hurry to tell you.

 

[garageman402]

Ok, the gauge is not the issue, the lack of oil during cranking is. As I said in my original post, I can crank it 20 sec, then check the oil level & it hasn't moved. If it's pulling oil, the level will drop because it filled the system. If I start it, then the level is lower when I check it after allowing plenty of time for it to drain back. If in fact the gauge is not registering, but it is pumping oil, then I should have pressure immediately upon startup, which I do not.

 

[CleanSump]

Hook up a mechanical gauge and check it. You can get a loaner or rental at your local brick and mortar chain.

 

[ls1mike]

Ok, the gauge is not the issue, the lack of oil during cranking is. As I said in my original post, I can crank it 20 sec, then check the oil level & it hasn't moved. If it's pulling oil, the level will drop because it filled the system. If I start it, then the level is lower when I check it after allowing plenty of time for it to drain back. If in fact the gauge is not registering, but it is pumping oil, then I should have pressure immediately upon startup, which I do not.

How many miles are on it. I think you are over thinking this. So what are you disconnecting to just crank it and what are you trying to accomplish?