Ok so where do I even get started (TLDR below if you don't want to read the whole story)...
6 months ago GTI started to misfire very badly under load (160k on the clock). Soon after it started to throw very sporadic oil pressure warnings. At this time, I was very concerned and started diving in to the engine to see what was going on. Here's the time line and what I've done so far...
Edit: All of this was done with a mechanical oil pressure gauge so I know it's legit low pressure and not just a faulty oil pressure switch.
First thought it was oil sludge. Tried seafoam and engine flush, drove for a bit and oil pressure issues only continued. Next removed oil pan to inspect oil pump and pickup tube. Cleaned everything and checked oil pump, which looked ok so I put it back together and hoped for the best. Well, I got the worst and on the trip ended up spinning a rod bearing.
After this I realized I was in for the long haul. Come hell or high water, I wanted to get the car back on the road and decided to do a rebuild...
Pulled motor and found that I had spun 1 rod bearing and had pretty bad wear on my mains as well. Also found that one of my balance shafts had started to wear pretty badly and would need to replace the oil pump.
I took the crank to a machine shop to get it fixed, ordered the oversized bearings, new forged rods, new seals, new rings, new gaskets, and whatever hardware I needed. Instead of spending over 1500 on a new FSI oil pump I put together a kit to do the 1.8T oil pump conversion.
Once I got the crank back I did a really thorough install, including tons of cleaning, dusting, and plastigauge to make sure EVERYTHING was in spec. Gapped the piston rings, cleaned up the pistons, installed new rods and used proper measurements, install steps, assembly lube etc on everything.
Put the motor back in the car and I thought I would be good to go. Well, I was wrong and oil pressure issues persisted. Figured I probably had top end damage as well so I checked the cams and sure enough, wear on the cams themselves as well as the cam cradles. Ordered a completely assembled new head from VW at this point.
Installed new head and as before, still having oil pressure issues. I was pretty stumped at this point, having fully rebuilt the bottom end and putting on a brand new head (which included all the cams, timing chain housing, etc). I figured it was worth it to try a new oil filter housing in case it was a stuck pressure relief valve. I also checked the oil cooler and made sure it wasn't damaged or obstructed in any way when I had the filter housing off. It all checked out fine. Tried new housing and still was having oil pressure problems.
Just for reference I'm seeing about 25-30psi of oil pressure at 2k once warmed up where I should be seeing a minimum of 39psi per the VW manual.
Car had oil pressure issues (160k on the clock). This lead to engine damage, including a spun rod bearing.
Replaced: Oil pump (1.8T conversion), rods, all bearings, seals, gaskets, piston rings, oil filter housing, cylinder head (complete assembled from VW)
Repaired: Crank (machine shop)
Checked and good: Oil cooler
All assembly was done correctly with proper procedure and plastigauge to check clearances, everything spec'd out within acceptable limits. At this point car continues to exhibit oil pressure issues. I'm seeing about 25-30psi @ 2k rpms where VW says minimum spec is 39psi @ 2k.
This leads me to where I am today. Low on motivation, out about $3300, TONS of time and headache (6 months now), and still no closer to fixing this oil pressure problem. I've talked to mechanics, other VW owners, general gearheads, and every forum post I could possible find to no avail. Every time I thought I figured out the issue, it only lead to more problems, more money, and no solution.
My only possible thoughts now are either the turbo or a crack in the block some where. Since the motor has never been overheated I highly doubt there is a crack in a cast iron block. That leaves only the turbo. I DO have the green light to order a new turbo, but I'm tired of throwing money at this thing. That's where I need your help. Do I order the turbo or is there something I'm not seeing here?
Anything anyone can contribute would be great. Right now I just need some help and a little encouragement so I can get my VW back on the road...