1991 Master t35d HELP-white smoke advice?

Hi. Any advice would be really appreciated as I'm having a problem sourcing a manual to refer too (any ideas)? My new to me 1991 Master t35d ex-ambulance converted camper has white smoke from the exhaust on start up and throughout acceleration? I've had a simple sniff test done (all good) & a new cambelt fitted. There is no water loss at all and no signs of water in oil or vice/versa, she starts after a few turns but idles and pulls well once started! Ideally I'd like to know what to check first starting with the simplest/cheapest options first if anyone can help me? :confused: Many Thanks