Read a bunch of threads of none apply to mine.

This is a brand new shortblock 5.7 in boat, because two before it blew up to what I would have assumed was a bad gauge. Apparently not so. To start off, the barbell has been verified with eyes on installed, the front plug can be seen in position thru the block side plug. With the block plug off oil spews from the side plug while cranking. From the side plug, the oil galley goes back and makes a down 90 into the oil pan, then goes straight up to the oil sender, where I am getting nothing. With the motor running it gets a trickle out of the sending unit port totally uncapped. With the oil filter off, oil poured into the sending unit port flows down free to the filter hole and out onto the floor. The o-ring on the pickup is most definitely in correct. Pulled the motor to verify. The pickup was very close the bottom of the pan so we lopped a 1/2" off it to try and get pressure, still nothing. Filter is a Purolator L14006. Oil pump was an LS6 pump the first time, stock truck pump the second time, new Melling pump now.

The only thing that hasn't changed through three motors is the used craigslist F-body oil pan and pickup tube. First was a junk yard LS1 I got for the heads and cam, second was a junk yard 5.3, this third one is a new build LS1. The gauge and sender has now been verified with working parts from another boat. Is it possible to have a blockage at or in the pan? Gonna pull it back out tomorrow and verify everything one more time, plus get a brand new from GM pan and pickup tube. It's almost like oil is going through the bottem end and back into the pan. No knocks on the bottom but the top is rattling like crazy.

Over the next couple of days will pull it out, smear new assembly lube on the bearings and double check everything. Something is being missed here and like I said, the oil pan is the only constant through three motors.

Open to ideas here. I'm tired of pulling this thing out.

 

I have always sprayed cleaner, pushed a bore brush, and used compressed air in all
of the oil holes before i start the reassembly process. Found a metal shaving in a oil hole
one time and a bunch of crap in another. Just my little experience.

 

There is a check valve in the pan right where the oil filter spins on. You can see it with the filter removed.
Have you checked it?
Have you cranked it with the oil filter off?
Tried a different oil filter?

Sounds like the pump is working.

Ron

 

Motor's out and fixin to pull the pan. Didn't know there is a check valve in there. Does it ever get gummed up or stuck?

 

Found the problem.. Something is missing here. Didn't even think this could happen. It's just bleeding oil back into the pan.

 

after reading your post went to tell you to check your oil pan gasket lol.. good find

 

that check valve isnt a check valve its a bypass valve in the event the filter becomes clogged.

 

That's your auto-bypass valve. It works with or without the filter!