I have fitted over two hundred Yanmars to boats and never had a problem, so continued on. the commercial users of these engines have been changing them at 40,000 hours so very confident in the product. Chinese Cummins reports are very mixed
The engines were assessed at Cummins in Brisbane and my decision was to replace them with new Yanmar 6AH2M 350hp and ZF boxes running same shafts and propeller size.
Old engines are at Cummins for their use.