I had same problem just after buying a '97 turbo r in nov 2017, 80+k on clock. My first indication was an erratic water temp guage. i thought it must be getting some shots of exhaust gas. When I saw the white cloud out back I knew for sure. It was steam from water entering combustion chambers. I stopped driving it immediately. i started the teardown,found the turbo was seized, i assumed from the pump picking up water from bottom of sump and feeding it to the turbo. I went no further as it was winter and I did not have indoor repair facilities. I had it done by RR/B specialists for that engine in Crondall, Hampshire. many more here know more about this than I do but this is my experience. The minimum book time for this job is I was told 35 hours. Much cleaning and difficulties with corroded and broken parts took this to 60 hours for me. The inlet, exhaust manifolds and turbo aren't easy to remove ( I think Crondall can do it with their eyes closed). the head gasket, as far as I can make out, had not changed design for many years, since when the engine produced much less horsepower. There is a much better, in my opinion, 3 layer metal gasket available which is identical except needing one extra hole for a locating pin. Crondall did not want to fit this as they do everything by the book and as they've had 600 bhp from this engine with no problems I let them go ahead. They did not remove the sump but did flush it a few times. i don't think they changed valve seals although I would have done so. At my request they also changed the thermostat, pump and radiator. Bentley parts are expensive. I would have used some aftermarket parts but Crondall didn't do that. they were very thorough and detailed in their report on work done. I sincerely hope i don't need to go back. It hasn't missed a beat since (except for its tracktion control skips at 70+mph) Anything else, please ask.