I never had this problem before the Turbo Swap that I am aware of but it could just be coincidental. I read a few threads and did a few minor things all ready trying to resolve the issue. From the beginning : I greased the drill bit and drilled my oil return hole in the pan, greased the tap as well, then tapped it. Threaded in fitting then flushed the oil pan with roughly 2 gallons of Diesel Fuel and let drain. Then changed filter and added fresh oil. Parts house was closed and all I had was a cheap STP filter. Drove it a few weeks and all seemed good. Leaving work one afternoon and started my car and I had no oil pressure. Valve train was noisy, Oil Pressure gauge showing no pressure. I turned engine off and looked for leaks and found none. Checked oil and all looked good. Restarted and revved engine a few times and all of a sudden I had oil pressure. Pulled car into shop and hooked my Oil Pressure gauge to it and took a quick reading. Had 13 PSI at idle and above 2500 it stayed around 40 psi. Pressures did not fluctuate much as the engine got hotter. I blamed it on the cheap filter. Went and bought a WIX Filter and drove it a few days and It did it again one morning when I was leaving for work. It doesnt do it all the time. Any other ideas from anyone before I start pulling my 218k engine out? ( edit : I did not drill through my pickup tube either)

 

Sticking bypass valve is my first guess.

 

Make sure you do not have a melted dipstick.

A member here installed a turbo, melted his dipstick, and fragments of melted plastic ended up in his oil pump causing the same problem you are having. It did not end well for him.

Whether it is a melted stick or some other debris, it is likely you have trash in the system.

 

It was what I expected but not what I wanted to hear hahaha.... is what it is. I know its not a melted dip stick.. read that thread all ready

 

Bypass valve is sticking. Pull the motor, drop the pan, change the pump, reassemble.