1999 5.3 oil pressure drop

[jumpingjack]

Hello, Because of leaking head gaskets at 100k I changed the heads and gaskets ( rebuild and tested heads). Now, after 1000 miles the oil pressure gauge shows a drop. For 2 mornings in a row I noticed on start up the pressure would only go to about 20 vs. 40+ before. it would jump up to 40+ after a little warm up. On the third day it started at around 35 and after driving it a few miles it dropped like a rock ( I watched it happed). Now it stays about half what it was and at warm idel it goes to ZERO and the warning message comes on. I changed the oil and filter twice with no difference. There is no knocking or lifter noise at 500 rpm and seems to run fine. Thank you

[j cAT]

Originally Posted by jumpingjack

Hello, Because of leaking head gaskets at 100k I changed the heads and gaskets ( rebuild and tested heads). Now, after 1000 miles the oil pressure gauge shows a drop. For 2 mornings in a row I noticed on start up the pressure would only go to about 20 vs. 40+ before. it would jump up to 40+ after a little warm up. On the third day it started at around 35 and after driving it a few miles it dropped like a rock ( I watched it happed). Now it stays about half what it was and at warm idel it goes to ZERO and the warning message comes on. I changed the oil and filter twice with no difference. There is no knocking or lifter noise at 500 rpm and seems to run fine. Thank you

I would suspect that the oil sender was damaged when the work was done,,,,hopefully....since its changing so much check the wires connector then if necessary replace...

this could also mean the head job was screwed up...

[jumpingjack]

It too awhile ,but, I found out what it was. Thanks for your help.

[pgun67]

What did you find out was the problem? Just curious as I have the same problem on my 2000 silverado. I have gone to High Mileage 10w30 and it seems to have helped some, but on cold mornings it occasionally drops to zero and the warning light goes off.