Marshall:
I know of two turbos that have failed in exactly that fashion, one on
my car and one on someone else's. Both showed serious lack of boost at
low speed cold and both showed excessive oil consumption. One (the MB
one) blew blue smoke on acceleration. My volvo TD didn't, but the
exhaust was full of coked oil and actually caught fire after the turbo
was replaced (quite an experience, having burning carbon blow out the
exhaust!).
The failure is not primarily a seal failure, it's a bearing failure.
They do wear out eventually, and bad bearings usually result in seal
failure before the turbo stops working altogether.
Peter
