Do you mean an EGR valve? Or a PCV valve?
Not familiar with the PCR valve.
I believe your engine has an EGR emissions reduction system. EGR is Exhaust Gas Recirculation.
Some pre-2015 engines had the EGR type of emissions control - which basically is a system for reburning a portion of the exhaust to reduce NO2 emissions. My
M59 tractor has it too.
The way EGR works so that when the engine is hot and the turbo is spinning, a portion of the exhaust gases are diverted first into a cooler and then back into the incoming air to be reburned with the next charge. NO2 is reduced, but at the expense of more soot formation.
The EGR emission system was specifically put on some engines as a way to reduce NO2 emissions because that is where the emission regulatory line was drawn at the time. And EGR was a known and inexpensive technology to reduce NO2.
But EGR emissions systems are touchy and if they are just a little out of whack then they make lots of soot.
That was no problem for the regulators, they had already written the later (Tier IV final) regulations that were phased in after 2015 and addressed soot as well as NO2 ....but in doing so we ended up paying for the complex emissions systems we have today.
It sounds to me like your EGR cooler is loading up with oil. I'm not sure why. But I'd look to the EGR system.
It's not expensive.
The EGR can be disassembled and cleaned pretty easily. Good ones sometimes chatter. That's OK.
Also, there is a therostatically controlled valve that controls flow into the EGR and thence to the EGR cooler. That valve looksat the water temperature and opens up the exhaust port to the EGR when the temperature is high.
Those are first places I'd look.
rScotty
BTW, if the turbo seal was bad I'm not sure you would notice it very easily becuse the oil would be gettig blown into the EGR cooler. Take another look at that seal - or run for a while without the turbo if you can.