07NBSChevy

Hey guys, so before I slap the engine back in my truck, I just wanted to double check my oil pump choice. I did a AFM/DOD delete along with a BTR Truck Stage 2 cam. Engine is a Gen4 Iron block LMG 5.3, I replaced my oil pump with a new GM stock one, #12586665, which is a common pump used in the LS1, LS2, LS6 and so on. Now should I have used a better pump such as Melling 10295 (Standard Volume, High Pressure) or Melling 10296 (High Volume, High Pressure) ? If it matters my shift RPMs will be set at 6k and Max would be 6200RPM. Before I removed the engine at hot idle I had around 22-25PSI and anything above 1800 RPM I had 45-50PSI.

1994Vmax

iTrader: (4)

Have you pulled the oil pan and removed the secondary pressure relief above the oil filter? If you don't you likely will not see any pressure above 55 to 60 psi regardless of the pump and bypass spring you have installed. Personally I am a fan of standard volume pumps regardless.

FFDP

iTrader: (2)

What he said, if you didn't remove the relief valve the pressure won't increase.

When you remove it you'll gain 10ish psi at heavy throttle. Idle and cruise will likely be about the same. Also, the stock oil pumps work great for what you are after.

07NBSChevy

I actually replaced that valve with a new one. I really dont need over 55psi. Just to make sure I have an adequate pump. A bump is PSI at idle or around there would be nice.

1994Vmax

iTrader: (4)

Well a bump at idle is only happening if you tighten up the clearance causing the loss in the first place. So a rebuild... lol. Unless of course your pump has a relief or clearance issue in itself. Tossing that stupid valve and not replacing it is a much better idea. I don't like a cheap little air compressor psv controlling my oil pressure that doesn't need to be there... especially since AFM is out of the question now.

07NBSChevy

I could remove it but I rarely have seen my oil pressure above 50psi as it is. So I really didnt think that removing it would do anything. I had the Shortblock checked by a GM Engine Tech buddy of mine, he checked the bearing clearances and what not and everything was in spec. So I should have that same oil PSI as a Brand new engine or thereabouts. I just want to make sure a New GM 12586665 Oil pump, which is the same pretty much as the Melling M295, is adequate enough or should I have used the Melling 10295 or 296 pump before I slap in the engine. Yes I do have a plug for the oil pan relief but that is only for 55+ oil pressure. Now I did see 50-55+ PSI when I did floor it, so removing the valve would see higher pressure at that point.

07NBSChevy

Here is pretty much how the engine sits now, except I have the heads on.

1994Vmax

iTrader: (4)

Correct but that silly little valve is also another leak point too. Have you ran anything since replacing it or is it something you just did? A regular M295 or equivalent is good for any LS. The original AFM pump is actually a slightly higher volume for the hydraulic circuit you have now removed so I wouldn't worry. Whichever pump you chose will do the job just fine.

07NBSChevy

I replaced the original 120k mile pump with a brand new exact OEM one, the #12586665. That was the one that was on there. Everything is new, have not started the engine. I did prime the oil system as well. Good to know, I was just second guessing myself on the pump. I will put the plug in the oil pan as well. I cleaned the oil circuits and what not and put in a new barbell, galley plug, oil pump, 3-Bolt BTR cam, 3 Bolt Cam gear, Timing chain, chain dampener, crank sprocket, and also used feeler guages to get the pump to the correct orientation.

Walters0687