If that plunger set it toast, yes. There is no other way I know of
that fuel can get into the oil other than through the bottom side of
the IP.
It's possible (although unlikely in my opinion) that a bad injector
(cracked nozzle) is dumping enough fuel into the combustion chamber to
flood it. In that case, expect lots more to be wrong with the engine
-- compression check will tell you.
Bad delivery valve seals cause the following symptoms:
Bad to horrible injector knock on affected cylinder, with NO change in
running with line loose. Cylinder may be completely "dead" at idle.
Normal fuel delivery with line cracked.
No smoke.
Near normal power and smoothness above approx. 1500 rpm, turbo comes up
but late.
Compression will be marginal on that cylinder if the problem has been
around a while (it was on mine).
Oil consumption will be normal -- on 60x engines, that means
essentially none.
Peter
