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Oil pressure low with oil level being fine

Zero6391

New Member
Joined
Feb 5, 2019
Messages
6
Location
New Mexico
Okay so yesterday I was driving on the highway and for the first time since I got the truck I saw a "oil pressure low" message flash on the IDC. It was only for a moment then went away. I watched it for the rest of my drive home with was only another 8 min after seeing the message and the message never came back and I was watching the oil pressure gauge as well and it moved once while I was turning and it dropped from 80 psi down to 60 then shot back up to 80 and stayed there. It didnt move on the next 3 turns or when I put it in reverse or when I put it in park. It's not tripping a check engine light and i checked oil level and it is fine. Now ever since I got the truck the oil gauge has always been pegged on that 80psi mark this was the first time I've ever seen it move. What could be the cause of this random message? I've read up that it could be the oil pick up tube o ring and I've also read up about a small filter that's near the oil pressure sensor that is blocking flow. But the only people who talk about this filter are the 07 guys so I dont even know if my truck has this filter. My truck is a 2003 chevy avalanche base 4x4 with a 5.3L and about 160k miles. I've always used Mobil one full synthetic 5w-30 and mobil one filters. And actually I just did an oil change last month. Engine isnt making any weird noises either. Havent driven it today but I'll be going to work tomorrow and I drive about 20 min on the highway to work. I'll continue to watch it but I want to see what things I should check before assuming the oil pump is going out
 
Oil pressure being pegged at 80 all the time indicates a possible bad oil pressure sensor.

Your normal hot oil idle engine speed oil pressure should be close to 40 and your hot oil cruise RPM oil pressure should be close to 55.

Cold oil readings may be a little higher than those listed above.

About the only time you should be seeing 80 or close to it would be at wide open throttle.

I would start by installing a new OEM oil pressure sensor and go from there.

Your 2003 will not have the little filter under the oil pressure sensor.

That began in 2007 with the AFM engines.

A bad oil pick up tube o-ring will cause low oil pressure, not a pegged oil pressure gauge.
 
I was thinking that too but it moved from the 80 to the 60 then back to the 80. But I'll go ahead an change that out this week and watch the IDC for that oil pressure low message again. It's just weird it would throw that message out and nothing be wrong. I heard that a bad sensor would throw a check engine code but I have nothing. Is the o ring a common issue for low oil pressure on these engines?
 
My 2004 with 230K miles on it had begun to have lower oil pressure issues a while back.

First thing I did was change the oil pressure sensor since that was the easiest thing to do.

My oil pressures were still low and I had also had my cluster upgraded during that time, so I was reasonably certain the problem did not lie with a bad stepper motor in the cluster.

Next, I had the oil pick up tube o-ring changed.

That helped somewhat, but the low oil pressure issue came back and got worse in short order.

I then had a new oil pump installed.

My oil pressures are now back where they used to be.

I spent a lot of time and money getting to the bottom of this.

You need to start with the sensor and go from there.

That might be your only problem and it will be cheap and fairly easy to find out.
 
Yea I'm just wanting to knock out the cheap fixes first before assuming it's the oil pump. I had my cluster rebuilt with all new stepper motors so I know that end is good. I ordered a new AC delco oil pressure sensor last night and it should be here by Wednesday or thursday. The o ring looks to be a pain to replace on the 4x4 models but it seems to be a problem a lot of people have, on youtube anyways. I drove to work this morning an watched the pressure gauge and idc like a hawk. It's a 40 mile trip one way with 35 of those miles being highway. But the gauge stayed steady and did not move and no messages flashed on the idc. I listened to the motor at start up and when I arrived at work and there was no weird noises, motor sounded like a normal running motor. So I'm kinda leaning to the oil pressure sensor as the culprit. I've never had an oil pump go out before so I'm not sure if mechanical ones can work intermittently or if they just die all at once? But I suppose I'll know more once I get the sensor and install it to determine if it's just a bad sensor or something else
 
Well I've been carefully watching the gauge cluster and oil pressure sensor but I haven't gotten the message back and my gauge has been pegged out at 80 still. I added some Lucas oil stabilizer as well. I got my oil pressure sending unit yesterday. Ordered a ac delco unit from rock auto for about 37 bucks. I installed it it today which was a pain in the arse but I got it done. The sensor was kinda loose, I was able to break it loose with my hand. I tightened my new one one just hand right with just a little extra umph with a ratchet and now my gauge is working for the first since owning the truck which is pretty neat. At idle (500rpm) my oil pressure is about 30-35 and at cruising (1500-2000rpm) my oil pressure is about 40-45psi and at WOT all the way to 5500rpm my oil pressure got up to 60 psi and it was pretty consistent through out the test drive. So I'm guessing that was my only problem. I'll continue to watch it and see if anything strange happens. But at least it looks like I saved myself from having to remove the oil pan and front diff to replace that o ring
 
This looks good!

(y)
 
Well I figured id coma back and do one final update. been driving the truck normally for the past week and have not gotten that message back so im gonna say its safe to say my only problem was the sensor being bad. which is good cuz im in the process of moving and don't really have a location to really be trying to replace the o ring on the oil pickup tube. if everything stays fine thru the winter ill change that out next year just for peace of mind. but my advice to anyone having the same problem just replace the sensor and see if that fixes the problem! you just might luck out like me!
 
Awesome! Thanks for the follow up. Good luck with the move, we did that this summer and hope I don't move ever again.
 
Zero6391 said:
Well I figured id coma back and do one final update. been driving the truck normally for the past week and have not gotten that message back so im gonna say its safe to say my only problem was the sensor being bad.

Great to hear a cheap fix did the job. Congrats
 
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