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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 29534
Experience:  GM Grand Master Technician 2007. 14 years experience.
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000 miles and suddenly lost oil pressure..pressure sensor..engine runs

Resolved Question:

I have an 05 5.3 vortec with 85,000 miles and suddenly lost oil pressure. I have replaced the oil, filter, & pressure sensor with no change in condition. I even changed the oil and filter a second time increasing the weight from the recommended 5W 30 to 10W 40, which didn't increase the pressure more than 1 PSI or so.The engine runs about 18 psi pressure cold and about 3 psi hot. Sense the engine has relatively low mileage and I've religiously changed the oil, I suspect the pressure relief valve in the pump is stuck open or the pump itself is bad. My questions are: 1) Is it possible to change the oil pump without completely removing the oil pan to access the pickup? The vehicle is a 4wd and I was told removing the oil pan requires the front diff to be lowered. I'm not to worried about the pickup screen being clogged because I've always used good oil, changed it every 3,500 miles, and the engine only has 85K miles on it. 2) Can the pump "o" ring be replaced without removing the pickup? 3) Is there anything else I should try before replacing the pump?
Submitted: 6 years ago.
Category: GM
Expert:  GM Tech (Cam) replied 6 years ago.

GM Tech (Cam) :

Hello, I'm Cam. Please include all the details about your issue so I can accurately advise you. I cannot see your vehicle so please be detailed

GM Tech (Cam) :

Do you get a low pressure warning in the dash?

Expert:  GM Tech (Cam) replied 6 years ago.
Do you get a low pressure warning in the dash or is it only the gauge that is low?
Customer: replied 6 years ago.
Yes, once it's hot and the oil pressure gauge indicates about 3 psi. I've had the truck hooked up to a scan tool which reported 5.98 psi oil pressure, but the low oil warning was not present at that time, so the threshold must be somewhere lower than 5.98.
Expert:  GM Tech (Cam) replied 6 years ago.
Ok, then about all that is left is a failing oil pressure regulator that is part of the pump assembly around the crank shaft at the front. YOu need to remove the oil pan and front cover to replace these.
Customer: replied 6 years ago.
So to replace the pump, the oil pan has to be completely removed? If so, is this only because it is recommended to replace the pickup and or pickup screen when replacing the pump or is there another reason the pan has to be completely removed? Please read all of my original questions.
Expert:  GM Tech (Cam) replied 6 years ago.
No you need t get the bolt out that holds the pick up to the pump.
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Customer: replied 6 years ago.
Relist: Incomplete answer.