With the first Waterboxer motors (WBX), the thermostat is housed in the casing which is mounted directly on the water pump. This was modified in 1986, the model year when the housing was connected to the water pump by a cooling hose and a metal tube.
The first thermostat housings were made of aluminum with the disadvantage that corrosion and breaking of bolts is common, the only thing you can do in such a case is to replace the complete housing (or part of it).
From model year 1986, this was abandoned and the thermostat housing was made of plastic. Not a bad choice but there are also disadvantages, in the long run the plastic will become brittle which is mainly due to the ever changing temperatures. Check the state of the plastic at every service and if hairline cracks appear it is advisable to replace the entire housing or part of it before it is too late and you end up with leakage which you don't want along the way.
The housing consists of two separate parts that are identical to the original. You can replace the top and bottom part separately.
Do not forget to order the necessary additional parts, these are listed on the options tab.
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