1999 GMC Suburban oil pressure drops as engine gets warmed

1999 GMC SUBURBAN
113,000 MILES • V8 • 4WD • AUTOMATIC
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DAVECINCY
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Recently on long trip I noticed my oil pressure was dropping on the guage lower than normal. I normal ran at a reading on the guage of 40. On the trip it was droppin down to ~ 25-30. This seems like a large percentage drop.

Prior to this trip I had the lower intake gaskets replaced and the oll changed. When I check the oil it was over full.

I don't seem to be losing oil or coolant. but have only driven about 3000 miles.
Mar 12, 2009 at 7:16 PM
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RASMATAZ
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Do you hear any type of knocking noises inside the engine? If not-try checking the oil pressure with a mechanical gauge if normal reading-replace the oil pressure sending unit abnormal could be the oil pump or the engine bearings-
Mar 12, 2009 at 7:25 PM
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DAVECINCY
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I will check sending unit. I am getting some what sounds like exhasut manifold noise during accelleration. not realy knocking. I was thinking oil pump. Why do you think it could be engine bearings?
Mar 12, 2009 at 7:57 PM
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RASMATAZ
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Check the oil pressure with a mechanical gauge and get back with the reading for evaluation
Mar 12, 2009 at 10:49 PM
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DAVECINCY
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where is the oil pressure sensor located? the manual I have says it is above the oil filter. I see nothing there. It looks like it is on the right side of the engien looking forward jsut above the oil pan? Is that right.
Mar 13, 2009 at 7:35 PM
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RASMATAZ
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What CID engine is this-305/350/454 ???????
Mar 13, 2009 at 9:35 PM
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DAVECINCY
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Here is what I know . In my owners manual it is describes as Vortex 5700 V8.

On some oil change reciepts they ID it as a 8 cyl. 5.7L 350 FI (R)

So I am guessing 350 CID.

The VIN is 3GKFK16R7XG539211

Thank you for the help
Mar 14, 2009 at 7:39 AM
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RASMATAZ
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Sir-The oi pressure switch is located on top left of engine near the distributor.

Thank you for the donation and for using 2carpros
Mar 14, 2009 at 5:02 PM