ZERO Oil Pressure

[InterceptorF]

Used 6.0, swapped the 317 heads for 862 heads, installed a Summit Racing Pro LS Vortec Truck Swap Camshaft SUM-8718R1 and new lifters. It ran fine for about 300 miles. Then one morning last week I started it and ZERO Oil Pressure. REPLACED cam retainer, Oil pickup O-Ring, added a mechanical Sunpro gauge and STILL Zero Oil pressure. I am going to replace the Oil filter next but something is definetly wrong because it runs without any chattering, I would expect it to start chattering is there was no oil to the heads. I have a new oil sensor to install but I do not think its the sensor. Something seems to either be blocking the oil passage to the sensor or there is another issue causinmg the oil pressure to fail. If the oil filter does not fix I am at a loss besides replacing the actual pump but that seems like it should give me at least 'something' on the gauges? what else am I missing? How do I check/clean the passages out?

 

[strutaeng]

Have you drained the oil and cut open the filter? Is that gauge calibrated? If it runs without any noise, maybe the actual pressure is good?

But if your bearings got wiped out somehow, no sense in doing anything else to attempt to fix the issue. Not saying that's your case though.

So the engine was taken from another vehicle and you replaced the heads and cam?

I have that cam on my 06 Suburban 2500 LQ4. I did an engine refresh when I installed it.

 

[Fless]

What year is the 6.0? I'm not sure of those had the screen underneath the oil pressure sender but if there is one it could be clogged. Look for it when you pull the sender.

Pull a rocker arm cover and run it for a short time, see if oil is getting to the heads.

 

[6speedblazer]

Id check that the oil pump bypass isn't stuck open.

pro tip. if you remove the oil galley plug from the driver side of the engine block, jam a hose and funnel in there and pour oil in it. If oil drains back to the pan, you have a stuck bypass valve. I have had this exact same issue happen on 1 truck i cam swapped for a customer and one i did a pickup tube relocation kit on. Both trucks were over 150K miles and the bypass valve was all scared up.

 

[Mudsport96]

Start it without the pressure sensor in the block to see if there is oil flow.... just kidding dont do that.

 

[Marky Dissod]

Start it without the pressure sensor in the block to see if there is oil flow ... just kidding dont do that.

Actually ... what if you crank it without starting it? Does it build ANY oil pressure?

 

[Tonyrodz]

Start it without the pressure sensor in the block to see if there is oil flow.... just kidding dont do that.

I did that once with my Express van lol.
The oil was flowing.

 

[Mudsport96]

I did that once with my Express van lol.
The oil was flowing.

Did it on a 350 on an engine run stand.... high volume high pressure pump.... the ceiling was dripping for an hour

 

[Scottydoggs]

if the engine aint knocking or tapping dancing up top its the sensor, or the dash cluster.

pull the sensor check for a screen, remove if theres one in the hole, then hook up a mech oil pressure gauge, thats the only way to know your true o/p.

 

[Mudsport96]

if the engine aint knocking or tapping dancing up top its the sensor, or the dash cluster.

pull the sensor check for a screen, remove if theres one in the hole, then hook up a mech oil pressure gauge, thats the only way to know your true o/p.

Except he said a mechanical gauge also showed no pressure.

 

[DRLexpress]

Plumb your mech gauge to the galley plug, front drivers' side of engine.