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Oil Consumption
Bad valve seals will cause excessive oil consumption. In an otherwise normal engine with good compression, rings and valve guides, bad seals will cause a loss of oil that can be detected on the oil dipstick. By keeping an accurate record of oil level on the dipstick, a noticeable oil reduction due to the oil being burned along with the fuel will be discovered. Bad seals will be confirmed if no oil leaks can be found on the engine to account for the loss.
Excessive Smoke
If the valve seals have deteriorated enough, the blue-white exhaust smoke will last longer after start-up and acceleration. Yet the smoke will eventually disappear after long engine operation or during periods of hot weather. Bad valve seals nearly always show an intermittent problem of oil burning, whereas worn piston rings and valve guides will smoke during all times of engine operation and never disappear.
Yes turbo shaft can have a lot of sideway play and does centralise when she spins up.