I've had a crossflow 4/4 for a while, but was totally unaware it could have a viscous coupling. :-)

is it part of the drive for the cooling fan ? eg:

https://www.burtonpower.com/water-p...0C5Pmjfrcpa1VEHQRWLE3nGmLC2gAhMNGuynKK8D

(Mine's got an alu rad replacement with an electric fan).


Dave
Blue 4/4 1969, Green +4 1953, (different) Green +8 1977