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Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 4508
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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Chevrolet Tahoe 4x4: I have a 2001 chevy Tahoe changed oil

Customer Question

I have a 2001 chevy Tahoe changed oil pump and oil pressure switch and oil pressure still dropes to 0 after driving for 45 min dont know what else it could be please help
Submitted: 2 years ago.
Category: Chevy
Expert:  Jerry Newton replied 2 years ago.
The first step for me is verifying this oil pressure with a handheld mechanical gauge. You want to be sure that the gauge is reading accurately before you go further. That's because going further means extensive engine disassembly and repair. The oil pressure in the engine is dependent on the bearing clearance. If the bearing clearance becomes excessive, oil pressure drops, and the fact that it happens as the truck warms up is consistent with this diagnosis. The likelihood is high that you actually need cam and crank bearings in your engine, which is another way of saying you need an engine overhaul, because you can't replace cam bearings without completely disassembling the engine. I know this is not the advice you're looking for, but that is the reality of the situation. This is why I always start this sort of diagnosis with a handheld mechanical gauge. If the handheld gauge agrees and says that your pressure is low, then you're likely going to be putting a different engine in your truck to solve the issue.
Customer: replied 2 years ago.
Is there a screen where the oil pressure switch is on my 2001 Tahoe
Expert:  Jerry Newton replied 2 years ago.
No, there is not. It's simply a threaded hole in the block.
Customer: replied 2 years ago.
Where do i hook up the manual gauge to
Expert:  Jerry Newton replied 2 years ago.
Remove the oil pressure sending unit, and attach the gauge in that threaded hole. It's located on the top of the engine behind and below the intake manifold.
Customer: replied 2 years ago.
And if thats reads good what could be problem someone told me that the pick up tube in oil pan might be the problem
Expert:  Jerry Newton replied 2 years ago.
This is the crossroads that is represented by putting a handheld gauge on the engine: it's either good on the gauge, meaning you have a problem with your dash gauge or the wiring, etc.; or the handheld gauge agrees that your oil pressure is too low, meaning that you have to find the mechanical reason for this. You already had your hands on the oil pickup tube, did it appear cracked, or the seal torn, or anything like that? There isn't any magic to the tube, it's just a tube with a screen, but it does have to be sealed at the connection, and not be cracked, or else it can suck air instead of oil. Your symptom, however, is consistent with the garden variety "worn engine" low oil pressure syndrome, as it starts out OK, but as it warms up, the pressure drops. This is very typically due to excessive bearing clearances. There is no outward way to "know" what's causing low oil pressure. If you have low oil pressure, you have to start disassembling until you find the cause, but you should go into it knowing full well that it could mean engine replacement. If you find a loose pump or a cracked pickup tube, that's all fine and well, but those would exceptions to the rule. More often than not, excessive bearing clearance is the culprit.