The engine has gone 800 hours and it is time to clean the heat exchanger and change the coolant fluid.
It is always a big mess to let out the coolant and this time I also remove the heat exchanger cooling pipe held in place by two rubber boots or sleeves.
But as you know one problem leads to the next one and this time it's no exception.
The system rinse must be done every 400 hours according to the manual and the coolant must be changed every 2. year to protect the system against corrosion.
The brass cooling unit must lie in vinegar a day or two to remove any deposits in and around the cooling pipes.