theres a product on the market called K seal fixes k series engines cooling problems in 10 min,s not sure how long it lasts tho (i was put onto this by a very good friend who ownes a car sales lot he puts it into every k series rover he sells and has only ever had one back wich he put another bottle in and it is still going strong)but it is common knoledge in the motor trade that there cheep for a reason (600 series with the honda engine exepted)