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Measuring Engine Oil Pressure

Old 12-23-2018, 05:06 PM
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Default Measuring Engine Oil Pressure

I am trying to help a friend trouble shooting an engine oil pressure issue. It is a 2010 Silverado with a 5.3 (140k on engine) and is stock with the DOD system. Once the engine gets nice and warm engine oil pressure slow bleeds off until the low oil pressure message shows up on the DIC. Last year he replaced the engine oil pressure sensor and cleaned the screen (but didn't replace it). How can I measure engine oil pressure to confirm if its the sensor again or this time the oil pump?

I have a code scanner that will show live data with oil pressure but is it measuring the data the engine oil pressure sensor provides the PCM? If that is the case that will not allow me to confirm the sensor or pump is bad is my thought. If my logic is incorrect on this, please let me know and why?

I have an adaptor to put in place of the oil filter and then hook up my mechanical gauge but discovered the hard way it's only good for LS engines made from 1997 through 2006 so it won't work for me in this case.

Anyone have a method to measure the engine oil pressure either mechanically or through a code scanner?

Thanks!
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Old 12-23-2018, 08:23 PM
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Put a mechanical gauge on it to check it
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Old 12-24-2018, 07:44 AM
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Yeah, tried that by trying to put an adapter where the oil filter goes but my adapter is only good for 1997-2006 because in 2007 they changed the size of the threaded pipe you screw the filter on. Where else on the engine can I install a mechanical gauge?
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Old 12-24-2018, 08:15 AM
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The sender for the oil pressure light is at the top rear of the engine. Get an oil pressure gauge kit from Autometer that will have a set of adapters for the hole the original sender screwed into. Connect that via the hollow tube to the gauge in the kit and you should be good. Just don't pinch that tube hard enough to break it or run it close to the hot exhaust manifold - an oil fire could quickly follow.

On my 150,000-ish mile 5.3 liter LM7 never rebuilt engine, I see almost 40 PSI cranking vigorously on this gauge with all spark plugs removed. Running, with cold engine oil, I'm at about 50-52 PSI at 2000 RPM which I'm quite happy with.

Rick
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Old 12-24-2018, 09:53 AM
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Thanks, I will check Autometer out.
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Old 01-03-2019, 01:21 PM
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I was able to get a mechanical gauge on it, thanks to B52's recommendation for the autometer adapter. It's a real PIA to get at that sensor in the back.

The oil pressure drops from 35 PSI to about 10 PSI at idle after about 10-15 minutes and the engine temp (per the dash gauge) gets to 210-212 (normal temp for this truck). The oil pressure drop triggers the 0521 code indicating low oil pressure.

So it's not the gauge. Anyone care to venture what the issue is? My guess is the oil pump or maybe the engine bearings? Any other way to confirm this without replacing the pump? Is it unusual for the oil pump to die at less than 150k miles on the truck?
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Old 01-03-2019, 06:10 PM
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Cam bearrings worn out.
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Old 01-03-2019, 09:42 PM
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Engine time?
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Old 01-03-2019, 09:43 PM
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Originally Posted by 64post View Post
Engine time?
Good time to delete the DOD.
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Old 01-03-2019, 10:03 PM
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In every instance that I’ve personally witnessed what your seeing, it turned out to be worn bearings. I’ve seen people fight the issue by using a higher viscosity oil, and even going to a high pressure pump, but it’s a fight you won’t win. You might buy some time, but ultimately you lose. It’s simply worn out. Hopefully I’m wrong...
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Old 01-03-2019, 10:13 PM
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From what you've described I'm going to say it's the oil's free flow through the worn/loose bearings in your motor. Low oil pressure could be caused from worn oil pump, pickup tube o-ring, clogged pickup tube, clogged oil filter, pickup tube to oil plan clearance, incorrect oil weight and when the bearings in the motor become loose your going to lose oil pressure. Have you tried running a thicker oil to see if your pressure gets better. Something like 5w40, 10w40m or even 20w50. These are not going to solve the problem though as 5w30 or 10w30 is what's called for in LS motor's.
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Old 01-04-2019, 10:01 PM
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I think I solved the problem. Much like the suggestions in this thread I thought it was something to do with the oil pump system/pick up or worse bearings going bad. What was keeping me from committing to that is that the oil pressure would slowly drop over a 10-15 minute time period to 10 PSI and just stay. If figured if bearings or the pump was bad the pressure would drop quicker than that and would go to closer to zero than 10 PSI.

The engine actually has 111k on it, thought it was higher but I checked the dash today. Turns out the oil filter was plugged up. I changed the oil and stuck on a fresh AC Delco filter and ran the engine. Oil pressure with a cold engine was over 40 PSI and when it was fully warmed up (temp gauge at 210) the oil pressure was steady 31-32 PSI at idle. Let it run like that for 20 minutes yesterday. I took it for about 10-12 mile test drive and the oil pressure did exactly what it was supposed to. I think because the owner had used a cut rate oil change facility he got a cut rate filter that plugged up. I had read on another forum where that happened to a 5.3. I have never experienced that in 40 years of being a self taught mechanic but there is a first time for everything.

So what I think happened is the filter plugged up and sent the oil pump into bypass. The pressure dropped as the oil got hot and thus thinner. 10 PSI much be what the factory setting is on the by pass valve, not sure. Bottom line is it all works like it should now. I will have the owner continue to monitor it and see if he notices any oil consumption or change in oil pressure.

Thanks to the forum members for the assist!
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Old 01-05-2019, 01:27 PM
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Doesn’t seem like a filter would have anything to do with the pressure, from a cold to warm engine standpoint, but I am glad to hear that the pressure has stabilized.
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