No oil pressure

[LindquistJon]

My ac compressor belt was gone so I put in a new one and now I have no oil pressure is there something I might have done to cause this to happen didnt have any problems beforehand.

[Blue Bowtie]

Is the instrument panel displaying zero pressure? Is there any unusual engine noise indicating low pressure, like rod or main bearing knock, or valve clatter?

[LindquistJon]

Yes low oil pressure light and gauge. Sounds very rough.

[Blue Bowtie]

What year/engine?

[LindquistJon]

01/5.3

[Blue Bowtie]

It is possible that the oil pressure sending unit was inadvertently disconnected. Verify that the connector is in place.

It is also possible, but unlikely, that installing the short/small AC belt has pulled the crank or balancer seal in a manner that is creating a loss of suction at the pump.

If the dash instrument still does not respond, it may be helpful to temporarily install a mechanical gauge to the test port near the rear of the intake and measure actual pressure.

[j cAT]

Originally Posted by LindquistJon

01/5.3

the vehicle you have should not have a dash indicator issue . some years did . the oil pressure sensor may have had a wiring connector issue.

questions what is the oil pressure ? what sounds are the engine making because if no oil pressure the lifters will be loud ticking . how many miles on it ?

possible the oil pump failed as you did the belt. possible you have no oil in the engine .If the engine was worked on internally the oil pump pick up could have fallen off. some have had this happen because of improper install. or pan gasket replacing etc..

[LindquistJon]

it is a loud ticking noise the oil pressure is hovering right above zero the engine is full of oil i had just changed it, but checked that right away after the low oil pressure just to make sure. it has 187,000 miles.

[Blue Bowtie]

I almost hate to suggest it, but what happens if the AC belt is removed?

If you understand the operation of the LS series engine oil pump you might see why a seal leak at the front of the timing cover and loose balancer could allow a suction loss at the oil pump:

[j cAT]

Originally Posted by LindquistJon

it is a loud ticking noise the oil pressure is hovering right above zero the engine is full of oil i had just changed it, but checked that right away after the low oil pressure just to make sure. it has 187,000 miles.

well the engine will need be taken out and checked for the oil pump and sump condition. you changed oil/filter after this issue suddenly appeared so not a bad filter.

[j cAT]

Originally Posted by LindquistJon

it is a loud ticking noise the oil pressure is hovering right above zero the engine is full of oil i had just changed it, but checked that right away after the low oil pressure just to make sure. it has 187,000 miles.

OK now I am guessing what it is............the oil pickup O ring .. these fail then the pump gets air bound sucks in air so no oil is sucked up .

what oil do you use conventional ? if so that may indeed be it.
conventional oils create generate acids that damage the seals .

[LindquistJon]

The oil pump was the problem it was a bugger but did it myself and save $800

[j cAT]

Originally Posted by LindquistJon

The oil pump was the problem it was a bugger but did it myself and save $800

that oil pump sump O ring is a common failure. it cracks then no pressure happens quick.

what was the pumps failure you know ?

[rhandwor]

http://www.ebay.com/ search item 322165269453
From the amount of o-rings on ebay it must be real common.