Low oil pressure

[Brandon1320]

I have a 2004 Yukon XL 269,*** miles I bought about two weeks ago. I changed the oil right after getting it. Filled to the second line from the top. Drove for about a week around town to make sure everything was ok with it and it ran fine. Took a 6 our trip to Tennessee, about 5 1/2 hours in I lost oil pressure. Checked my dip stick and the oil level was at the bottom minimum line. I haven't seen any oil leaking so I'm thinking it must be burning it. Got a fresh oil change and added a quart of Lucas high mile oil stabilizer. After that, the oil pressure rides about 20 psi on the dash gauge. I bought a pressure tester gauge from Auto Zone and that reads about 25 psi. So I am thinking my oil pump should be good? I have read online that the O-ring on the pick up tube is a common problem. It runs fine. No ticking or any noises. Had a mechanics stethoscope on both valve covers. It sounds smooth. Is there anything else I should look at to diagnose other potential culprits? It's a 4wd so pulling the oil pan is going to be a big task just to change the o-ring. Thanks for any input.

 

[swathdiver]

I have a 2004 Yukon XL 269,*** miles I bought about two weeks ago. I changed the oil right after getting it. Filled to the second line from the top. Drove for about a week around town to make sure everything was ok with it and it ran fine. Took a 6 our trip to Tennessee, about 5 1/2 hours in I lost oil pressure. Checked my dip stick and the oil level was at the bottom minimum line. I haven't seen any oil leaking so I'm thinking it must be burning it. Got a fresh oil change and added a quart of Lucas high mile oil stabilizer. After that, the oil pressure rides about 20 psi on the dash gauge. I bought a pressure tester gauge from Auto Zone and that reads about 25 psi. So I am thinking my oil pump should be good? I have read online that the O-ring on the pick up tube is a common problem. It runs fine. No ticking or any noises. Had a mechanics stethoscope on both valve covers. It sounds smooth. Is there anything else I should look at to diagnose other potential culprits? It's a 4wd so pulling the oil pan is going to be a big task just to change the o-ring. Thanks for any input.

You're on the right path, the easiest is the sending unit and if not that, then add two extra quarts when the pressure drops and see if it comes back up, this is enough to submerge the o-ring usually. Welcome to the forum.

 

[Brandon1320]

You're on the right path, the easiest is the sending unit and if not that, then add two extra quarts when the pressure drops and see if it comes back up, this is enough to submerge the o-ring usually. Welcome to the forum.

Thanks for help. I don't think its the sensor since the dash gauge and tester gauge are pretty similar. I think I'll try the extra oil and see if that makes a difference.

 

[Fless]

Don't drive it overfilled, just test it that way. You may need to get the nose down a little so if you have a driveway that tilts it might help.

 

[swathdiver]

Don't drive it overfilled, just test it that way. You may need to get the nose down a little so if you have a driveway that tilts it might help.

A guy on here drove his with the extra 2 quarts for a year or so until he could afford to fix it.

 

[Brandon1320]

A guy on here drove his with the extra 2 quarts for a year or so until he could afford to fix it.

Yea I didn't plan to drive it like that. I'll try to pick up some oil tomorrow and try it out. My drive way does have a little incline to it so hopefully backing it in is enough to cover that o-ring.

 

[Brandon2489]

I had low oil pressure issues about a week ago. Mine ended being the oil filter. Mind you it only had about 3k miles in the oil change. I changed only the oil filter with a different brand. My oil pressure numbers returned to normal. I did buy a oil pressure sensor and screen but am still waiting on the sensor to arrive. Will install both when they arrive. But the oil filter is a cheap easy thing to rule out. Good luck. Lots of smart people on this forum and very friendly.

 

[Brandon1320]

I had low oil pressure issues about a week ago. Mine ended being the oil filter. Mind you it only had about 3k miles in the oil change. I changed only the oil filter with a different brand. My oil pressure numbers returned to normal. I did buy a oil pressure sensor and screen but am still waiting on the sensor to arrive. Will install both when they arrive. But the oil filter is a cheap easy thing to rule out. Good luck. Lots of smart people on this forum and very friendly.

So my first oil change when I bought it I cheaped out and put an STP on it. When I got the oil changed the second time I put a Mobil 1 on it. Between that and the Lucas stabilizer it didn’t really help much. When I change it again I’ll look for a Bosch or Wix. Only reason for me not changing the sensor is I’m not getting a code for it and it reads roughly the same as the diagnostic gauge.

 

[swathdiver]

I had low oil pressure issues about a week ago. Mine ended being the oil filter. Mind you it only had about 3k miles in the oil change. I changed only the oil filter with a different brand. My oil pressure numbers returned to normal. I did buy a oil pressure sensor and screen but am still waiting on the sensor to arrive. Will install both when they arrive. But the oil filter is a cheap easy thing to rule out. Good luck. Lots of smart people on this forum and very friendly.

We are seeing that more and more lately. I used to lose about 2-3 psi when running a Mobil One Extended Performance filter over the ACDelco or K&N with the nut on the bottom. Nowadays that is all we use.

 

[Brandon2489]

I used the K&N and so far have had great results.

 

[Brandon2489]

I'm not sure if yours has the oil pressure sensor screen or not but keep in mind if it does always remember just because you put a mechanical gauge on that same port the screen can also give your mechanical gauge a faulty reading. So you may want to put a new screen or clean it and then retest with mechanical gauge. Also just because the switch is going bad doesn't mean you'll get a CEL. Hope that makes sense

 

[Tonyrodz]

I'm not sure if yours has the oil pressure sensor screen or not but keep in mind if it does always remember just because you put a mechanical gauge on that same port the screen can also give your mechanical gauge a faulty reading. So you may want to put a new screen or clean it and then retest with mechanical gauge. Also just because the switch is going bad doesn't mean you'll get a CEL. Hope that makes sense

Def won't get a cell for a bad sensor. Also, the nbs don't have the screen under the oil pressure sensor. The nnbs have that screen.

 

[Brandon1320]

So I added extra oil. It's just below the 1 on the dip stick (picture for reference). My oil pressure on a cold start up sits about 20. I never really paid attention to where it sat before I lost pressure. So I took it around the block to see if it would go up under load, around 4k RPM I can get it to just about 40 PSI. When I got back and revved to about 4k again it would raise up to just about 40 again. So does that sound like just the o-ring to anyone? I also included a picture of how low the nose was on start up since it was suggested to have the front end lower...

 

[Brandon1320]

Def won't get a cell for a bad sensor. Also, the nbs don't have the screen under the oil pressure sensor. The nnbs have that screen.

I feel like that is a little ass backwards to not get a CEL for a bad sensor...?

 

[Tonyrodz]

I feel like that is a little ass backwards to not get a CEL for a bad sensor...?

I agree. It would def make life easier if it did.

 

[clandr1]

So I added extra oil. It's just below the 1 on the dip stick (picture for reference). My oil pressure on a cold start up sits about 20. I never really paid attention to where it sat before I lost pressure. So I took it around the block to see if it would go up under load, around 4k RPM I can get it to just about 40 PSI. When I got back and revved to about 4k again it would raise up to just about 40 again. So does that sound like just the o-ring to anyone? I also included a picture of how low the nose was on start up since it was suggested to have the front end lower...

My o-ring went bad around 170,000 miles, so if yours hasn't been replaced, it's probably time. When my oil pickup tube o-ring went bad, it was in December (cold). When the truck first started up, the oil pressure was VERY low. Once the oil warmed up and became thinner, the oil pressure seemed to increase closer to normal levels. It seems to kind of mimic your situation.

Think of it like trying to suck through a straw with a crack in it - it'll be easier to suck up water (warm, thinner oil) than it is a milkshake (cold, thick oil).


Side note in case it's relevant: I've run Mobil 1 5w-30 High Mileage synthetic oil since around 80,000 miles, and have always used a "good" oil filter (used to be Bosch, M1, or Wix, but for the last few years I've been using AC Delco since they are inexpensive and still seem to be highly regarded).

Hope this helps.

 

[smcnair]

I use the GM filter and oil pressure has been perfect ever since I changed that o-ring. Yes, absolute pain in the ass in a 4WD...

 

[Brandon1320]

So I was able to drop my oil pan and I'm pretty sure I found the source of the low oil pressure. The pick up tube screen was completely covered with gunk. The bottom of the oil pan was full of sludge. My pick up tube o-ring seemed in pretty good shape but obviously I replaced it anyway. Cleaned the tube. Cleaned the oil pan. Pulled the plate off the bottom of the engine below the crank and cleaned that. Clearly this engine didn't have the best maintenance. Put it all back together and now my oil pressure is back up and running good.

 

[Tonyrodz]

So I was able to drop my oil pan and I'm pretty sure I found the source of the low oil pressure. The pick up tube screen was completely covered with gunk. The bottom of the oil pan was full of sludge. My pick up tube o-ring seemed in pretty good shape but obviously I replaced it anyway. Cleaned the tube. Cleaned the oil pan. Pulled the plate off the bottom of the engine below the crank and cleaned that. Clearly this engine didn't have the best maintenance. Put it all back together and now my oil pressure is back up and running good.

My van with the 4.8 was in the same condition. I also changed out my oil pump with a Melling hv unit.

 

[Sam Harris]

Good results! Hopefully no issue down the road. Anything older than a 2007 shouldn’t have a screen in it anyway.