I think I have a pinched oil pickup tube o-ring or the reused one isn't making a good seal. I'm pretty sure it wasn't red when I was putting the engine together. I've read about the different o-rings on here hoping I have the wrong one and not something else. Fresh motor only ran for maybe 10 mins total but not straight. Oil pressure fluctuates at idle from 20 to 40. Even dropped down to 0 this morning. I turned it off when that happened. Going to to check it again tonight after work. If it has oil pressure when I fire it up again I'm pretty sure it's the o-ring, but if I can't get oil pressure it's probobly stuck relief valve. If anyone knows the red o-ring part number or say how to get it at the dealership or anywhere else I would greatly appreciate it.

 

The part number I have for the Red O-Ring is 12584922.

Good luck, I hope you find your problem.

 

Thank you!

 

go to the dealer. but pay no more that 5$ for one.

 

Definitely sounds like the oil pump pickup o-ring is your problem, I'll keep my fingers crossed for you...you mentioned "reused" in your post, if that's the case, that's probably the problem

 

K checked truck tonight. A little history though. I reused the o-ring from the 6L long block that I got for my build. It was a running lq4 engine. I rebuilt it. Wasn't aware of the o-ring problem with the blue/black o-rings. Felt like a good fit when it went in. This fresh engine (except for the o-ring) has only been running for 3 days, maybe 15 to 20 mins total. Truck is still up on jackstands.

Oil pressure is there. Cranks up fine oil psi dances between 20 and 40 at idle. It takes about 2 seconds to get from the two readings. Bring the throttle up to about 2000/2500 and oil pressure is steady at 45 to 50, no movement. With a leaky o-ring should I still be seeing the movement at the higher rpm? I have another sensor on my 5.3 that I pulled out. Going to get it and see what it does. I've heard of them leaking inside the sensor and making a bad connection. Sure hope it's the sensor and nothing inside. Let me know what you guys think.

 

Tried another sensor, same deal. Dropin the pan this weekend to go in and put a new o-ring in and check the relief valve.

 

Dropped the pan tonight. Old blue-ish o-ring out, new red in. Definelty a tighter fit than the one that came out. Pretty much fell out as soon as I un bolted it. 50lbs and steady at idle now! Up to 60 with throttle. It should settle down to 40 when it warms up. Thanks guys for all the help.

 

For future reference:

GM Oil Pick-Up Tube O-Ring (1st Design)
12557752

BLUE SEAL
Specifics:

* Oil Pick-Up Tube O-Ring ea.
* Chevy/GMC Pick-Up (1999-2000 LS V8) 1st design
* F-Body (1998-2002)
* Cadillac CTS-V (2004-2007)
* Corvette (1997-2008)
* Thickness = 3.55mm (0.140")
ID = 23.60mm (0.930")


GM Oil Pick-Up Tube O-Ring (2nd Design)
12584922

RED SEAL
Specifics:

* Oil Pick-Up Tube O-Ring ea.
* Chevy/GMC Pick-Up (1999-2000 LS V8 engines with 2nd design pick-up tube)
* Trailblazer (2003-2008 With LS V8 engine)
* Hummer H2 (2003-2008)
* Hummer H3 (2008 With LS V8 engine)
* Chevy/GMC Pick-Up (2001-2008 LS V8 engines)
* W- Body (2006-2008 With LS V8 engine - Impala, Lacrosse, Grand Prix)
* Thickness = 4.20mm (0.165")
ID = 20.69mm (0.815")

2nd Design pickup tube (red o-ring) shown below



Specs lifted from a posting by 69LT1Bird. :-)

Thanks, Rick

 

Good stuff Rick! This lil o-ring should be something everyone needs to replace when they do their engine build. Even take the pressure releif valve out of the oil pump and inspect it. Can't tell ya how much I was dreading taking my fresh engine back out of my truck for something as simple as this. Now I know and hope everyone else knows.