Prob been asked 1k times but here goes. Truck started having low oil pressure problems , 25lbs driving and fall to almost nothing at idle , took pickup tube out cleaned everything, replaced o ring, didn't change anything, removed valve covers , wasn't gunked up , got a decent lifter tick goin on , so removed oil pump ,and I see some wear on housing and gears but not so much it jumps out and screams there's the problem. Motor was running like a sewing machine, ran real good b4 this happen. I'm gonna recheck pressure valve in pump and make sure it has fluid/ smooth movement and no hang ups. Anything is possible but i don't believe it to be cam bearings but I'll try look up past crank and make sure one hasn't walked out on me , b4 I replace pump , anything else I should look at ? Is there any excessive tolerances to check for on pump?

 

Could be the oil pressure switch at the back of engine. Could be switch or screen under switch is clogged. Common problem.

 

Thanks for reply , the guage is reading right and don't have a screen under it on this model,

So I replaced pick up o ring etc , no help , took oil pump off and there is very very little wear in the housing and gears , cant catch a nail on anything, pressure relief moves freely no hanging. I cleaned oil pump real good with a scotch Brite, lubed it up and put it back, same thing and still got a lifter hammering. I've got driver side head off now , main oil galley is clear , few of the clips in the lifters look like hell , deformed, possibly missing pieces of clip but I'm about positive lifters is from low oil pressure , with the pump looking as good as It did and it was tight, could that be the whole issue here. Cam looks ok , like anything else with 200k miles.

 

Make sure you use a new o ring from GM you can pick them up fairly cheap from a dealer the after market I rings don't seal as good and cause loss of pressure. Had this happen and the new o ring fixed my issue I've put 20k on my 2003 5.3 and it's still holding 38lbs before I put the new o ring I had 26lbs of pressure

 

To update thread , spun cam bearing and broke it in half , sure seems like it would had been making a hell of racket. I found a fresh block out of machine shop comes with all new bearings, crank was checked and cleaned up , has bunch new parts for 500 , guess guy needed the money. Just gonna build the new one , now trying decide if I should put little cam in it or not , nothin crazy. Got a local guy that can tune it for 400. Seems like a good idea since I won't have much $ in it

 

Out with old almost ready

Fresh out machine shop. Any gurus got any suggestions on improving or cheap power mods while im putting it together. This my 1st ls im building, have done a many old school sbc and bbc , actually this is 1st ls thats went down on me but lookin forward to fresh motor