I recently rebuilt my engine, with and LE2 top end. My oil pressure increases with RPM until about 4000, then drops to around 20 PSI and continues to flucutate a little.

Anyone ever have anything like this happen.

I originally replaced the stock oil pump with a high volume until I saw this happening. I went back to a stock replacement. It still is happening. I originally thought that high volume pump was sucking the pan dry.

Any help would be greatly appreciated.

 

What weight oil are you using?

I used to run valvoline 10w30 and noticed the same fluctuation but not quite as extreme. Then I switched to 0w40 Mobil1 and the pressure has increased all around as well as staying up at WOT now.

 

I ran 5W30 originally while breaking the motor in. I switched to 10W40 and had the same effect, both Valvoline. The machine shop recommended not putting in synthetic until it had 5K miles.

I was also curious where I could get the white spring for the oil pump.

 

It is a GM part, so the dealer would be the place.

 

My car does the exact same thing. I have it narrowed down to the oil climbing up the back of the pan under hard acceleration, mainly because pressure drop is worse in the bottom three gears, and even worse when I spray it. From a highway roll in third gear it'll hold 60 PSI all day. I have a HV pump with a stock pan, but I highly doubt that's the problem, because as soon as the car starts accelerating hard the pressure drops like a rock down to 30 PSI or so.

 

While parked, if I rev the engine to 4000 RPM and hold it, the pressure will jump around about 10-15 PSI. I have changed the pump twice already, and I'm fixing to drop the pan again and put the white spring in the oil pump to see what it will do.

 

What are your brg clearances?
It sounds like the oil pressure is popping the relief valve but a good pump with the right clearances shouldn't build enough pressure to do that.
What is the pressure just before it drops?
If your clearances are tight maybe ya need to go with a straight 20W dino to see if that helps.
If your clearances are tight then it might cause that but a bigger spring will cause it more or build TO much pressure which if over 80psi hot with tight clearances WILL cut a nice groove all the way around the brgs even if the crank has chamfered oil holes.

 

Mine does this after warm up. Holds 45 psi when cold then gets to op temp and jumps all over as you described. Check your oil filter. Hopefully you won't have what I had. Bearing particles the 1st layer of the tri-metal bearing. Have to rebuild but for now I'm going to try a thicker weight 20-50 and see if that'll help til spring.