thanks for all your replys. Funny thing when boat idleing temp goes to 0 then when on the move again reads 140 which is what stat is rated at, very strange maybe head gasket gone on one bank. It has already had one done back in 2010, gasket had gone between no,s 6 and 8 in history file. thought it was funny both wern,t changed at the same time though .Am looking into buying new long block as timing cover rusty and its a engine out job to change,shame as very sweet sounding engine. As quoted on boatmad break out another £3000 lol......