Question about 1999 GMC Sierra

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High oil pressure and knocking in the engine

I drove 200 miles problem free turn the truck off for an hour went out and started the truck my oil pressure climbed over 550 kpa and engine began knocking I have changed the oil filter and oil but the problem remains the same. Anyone have any ideas about this one?

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  • ryan_rushton Dec 10, 2008

    Yes I am using the proper type of oil I have 10w30 in it right now.

    Everyone i have talked to can't understand why my oil pressure would rise like that.

  • yadayada
    yadayada May 11, 2010

    are u using the correct grade of 5W-30W or 10W-30W? heavier oils starve the bearings of lubrication because of the very tight bearing clearances that newer engines know use.

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There is a pressure relief valve in the oil pump, it is stuck closed, this happens now and then, seen it 2 times, since the oil pump is a positive displacement pump it can produce 100's of pounds of pressure, the reason for the noise is that u have allot OF pressure but very little volume, the bearings are being starved for lubrication, replace the oil pump, DO NOT DRIVE THE TRUCK, U WILL BURN OUT THE ROD AND CRANK BEARINGS.

Posted on Dec 10, 2008

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