I have a 2003 Tahoe with 5.3L with 162K miles, when I start it in the morning the oil pressure is around 40 psi but after it gets hot while driving the pressure will stay around 40 while driving and when i slow down it will drop till right over 20 psi. I know my truck has started leaking oil which i think its the rear main seal. May need to check the sending unit but i replaced that 2 years ago. Would the leak cause my pressure to be low? I run Pennzoil High Mileage 10W-30. Also while driving my truck makes a humming noise almost like off road tires make. I had the alignment checked because the front tires looked choppy on the inside and it was all good and everything was good and tight on the front end and tires rotated. I was told it could possibly be the shocks that need to be replaced which they do but would that cause the off road noise while driving? Any help would be appreciated. Thanks
OIL PRESSURE and NOISE???
- Thread starter ALVTAHOE
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about20ninj45
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You can try to figure out where your leak is coming from by de-greasing the engine and drive it for a couple of days to find out where its coming from. Two main components are the oil sending unit and the rear main seal. The humming noise your hearing could be from the front diff. I would also check to see if your vehicle makes a large clunk when changing gears
about20ninj45
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Reply sorry i was assuming it was 4wd, yes, possibly hubs. You could also put your vehicle in neutral at cruising speed to see if its induced under acceleration only
about20ninj45
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could also be axle phasing/growl and you also want to degrease the back of the block where the oil sending unit sits.
02Burgundybeast
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Oil pressure seems normal to me. At slower speeds or idle it should be around 20. Driving on the highway will be around 35-40 once warm.
about20ninj45
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Mine is at 35-40 on startup and 50-55 on highway
02Burgundybeast
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I looked up the GM specs for pressure and thats what they said was normal operating range.
about20ninj45
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Yes with an actual gauge reading, not the dummy gauge on the dashboard thats known to read atleast 25% higher than actual pressure. It would also depend on the proper weighted oil. OP what are you running?
about20ninj45
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That should be fine as long as outside temps aren't below freezing. If your driving under freezing like conditions (32*F) its better to run 5w-30... but to each their own. If you want to know your real oil pressure, install a gauge, but i wouldn't worry to much at this point.
#1taho
5150TAHO
there is a post here.(sorry I don't know to post the link here for you) but the pick up tube for the oil pump had a o-ring of some sore that goes and causes an low oil pressure problem. if everything else checks out maybe see if that will help.
ccapehartusarmyINF.(ret)
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ive been reading when these motors get alotta miles on them the o ring for the sump needs to be changed out
SLCHOE
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Your oil pressure is 40 in the morning (idle) because the oil is thicker when cold. After getting it to operating temp it will drop.
02Burgundybeast
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Mine had low oil pressure, 6-7 while at idle, lift tap at start up. Ended up being the o ring. Replaced the o-ring and it was good to go. Start up pressire is around 50+ and idle is around 18-22 at idle.
