P00AF - 'stuck' with new turbo

[rajjinator]

Last night I stuck a cheap borescope into the currently open exhaust ports on the head and noticed some greeny looking specs on the valve stems and around the guides. Today by complete coincidence I knocked the old egr cooler on the garage floor and some coolant poured out onto a black mat and I noticed some green crystals.

Now I am very confused for two reasons. Firstly, what on earth is it? Perhaps steel seal or some other variety of stop leak has been added to try and cover up the failed EGR cooler?


The second reason I am confused is how could this be getting into the exhaust stream if the source is indeed the coolant? The EGR is brand new (engine came out to replace the turbo and it was done at the same time). The only other thing would be the chargecooler I guess. Very strange, but I obviously need to find the source before refitting the turbo!

Green specs on the valve stems:



green flakes/crystals found in the old EGR:

 

[rajjinator]

What a rollercoaster of emotions... The green specs on the valve stems are in fact just weird artifacts/light reflecting on what i assume to be oil, from the camera light. The green specs in the coolant are definitely a thing though and still of unknown origin. I've decided to pull the head back off and change the valve seals to eliminate those as a source of oil in the turbo. I'm kicking myself for not doing them when i had the head off last week, but they didn't seem to be leaking.

I guess i'll also pull the adblue injector off and have a look for any obvious signs of DPF damage or excessive amounts of adblue being injected. The turbo guys suggested excessive back pressure could cause adblue to be pushed back into the VNT mechanism. I can't imagine it to be that personally as the VCDS logs showed only 5 millibar differential pressure at idle.