Turbo Seal Wear (High Mileage)
Symptoms
Blue smoke on cold startup (oil pooled in the turbo housing overnight drains into the exhaust when started). Blue smoke on deceleration (intake manifold vacuum pulls oil past the compressor seals). Oil residue in the intercooler piping. Increased oil consumption without external leaks.
Cause
The CT-20 turbochargers use oil-fed journal bearings with carbon face seals. After 150,000+ km, the seals wear and allow oil to migrate past the turbo shaft into either the exhaust (turbine side) or the intake (compressor side). Heat cycling accelerates seal degradation.
Fix
Rebuild both turbochargers.
A turbo specialist can reball and reseal the CT-20s for $600-1,200 (both turbos).
This is worthwhile if you're keeping the sequential system.
If you're planning a single-turbo conversion, simply do the conversion and discard the worn CT-20s.
While the turbos are out, replace the oil feed and drain lines.
Restricted oil drain lines (from carbon buildup) are a common secondary cause of turbo seal failure, the oil can't drain fast enough and builds pressure behind the seals.
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