Thick white smoke shortly after startup, happens when cold and at operating temperature.
Variables:
- Coolant and oil temperatures are normal.
- Oil pressure is normal at hot idle (> 60kPa) and seems normal at higher engine revs (200+ kPa) running Delo Silver 20W-50. It is possible the oil is too thick and leaking past turbine seals.
- Coolant level has not dropped. Oil level has not dropped.
- Boost is slightly lower at 50 kPa with wastegate open compared to ~70 kPa, boost spikes as usual at peak 100 kPa.
- When cold starting, engine turns over normally and starts within a few revolutions.
Car drives pretty much normally, but produces LOTS of white smoke.
Figuring out what's causing the white smoke:
- Head gasket failure, causing either oil or coolant to get into combustion chamber. Possible warped block or cylinder head.
- Turbine seal failure, causing oil (coolant less likely) to enter exhaust.
- Worn cylinder wall or ring(s) causing oil to enter combustion chamber.
The BOV has sprayed a lot of oil on the underside of the hood, towards which it is pointing, so an oil catch can is looking more necessary. This also points towards a compressor side turbine shaft seal failure.
Let's solve this smoking problem first.
Oil Change:
Drained hot Delo Silver 20W-50 (19.1 cSt) at 80°C, poured in PSO Carient "Full Synthetic PAO" 5W-30 (10.67 cSt). Kept existing filter.
Smoke immediately reduced in thickness and intensity, continued to decrease over 15km drive. Oil pressure drops to 50kPa at idle. Quite dramatic increase in performance, as expected. Getting to 100km/h is much faster than before.
It might not be the head gasket after all. Things are pointing towards a turbine seal issue with the thicker oil.
Oil Thickener:
Adding Kixx Oil Treatment (374 cSt at 100°C) in 100mL steps to see what happens.
With 100mL, oil pressure at 100°C is ~60kPa.
With 200mL, oil pressure at 100°C is ~70kPa.
With 300mL, oil pressure at 100°C is ~70kPa.
Car's been running and driving, 50km today. Smoking, still, but developing boost and pulling well at peak 100 kPa. I have dialed it back down a little bit, and peak boost is now a little shy of the 80 kPa mark.
The search for yet another scrapyard turbo begins.
Wait A Minute... The Oil Drain
A backed-up turbo will always leak oil, since there are no actual seals that prevent the pressurized oil feed from breaching the exhaust or compressor sides of the turbine if it doesn't drain properly. This thought struck me quite late in the day, so I took a look underneath.
You can see the kink, as well as the oil making its way down from the top of the hose. I took it off and ran the engine, letting about 950mL drain out into a beaker. I then slid the hose further in to loosen up the kink, although I couldn't eliminate it completely - the hose needs to be replaced for that. Finally, topped up the oil with more PSO Carient Full Syn PAO 5W-30, quadruple-checked the levels, started and idled the engine.
No more smoke. 30min idle, no smoke. 20km of driving, no smoke.
In fact, the car is performing better than it has ever performed. At WOT, I can now hear crunchy noises for the first time since I sorted the ignition issues - will take a smidge of distributor angle advance out.
Oil pressure is 60kPa at idle at the observed peak oil temperature of 100°C. With 5W-30! (and whatever is left of the 300mL Kixx Oil Treatment in the sump.)
Fingers crossed there are no more issues. Adding oil catch can soon.