I do not consider it a maintenance issue on the 80 (unlike many modern engines) but I do know they can fail. Failure tends to be a slow process but never seems to be noticed until it is too late. I have taken a paint brush with white paint and painted a stripe across the two pulleys on mine, when under the bonnet a quick glance tells me the two halves bonded by rubber are still in sync with each other.
I also considered that as I have removed the engine cooling fan that there may be additional heat in this area, but now into about three years with Spain's hot climate I still see no problems with heat.
FWIW, when out 4x4..ing and when leaving the car to walk an area I leave the engine running to keep the AC on, it is not uncommon for my engine to be running four hours at low revolutions including idling for extended periods, IMO heat is not an issue.
The real threat IME is when the AC compressor seizes up. A friends 80 had this happen, the initial problem was the AC belt snapped whilst he was driving, plenty of smoke but was able to continue his journey, the compressor and belt replaced some time later. It was at least a year later before he had charging problems, the alternator dropping it's output when loaded with lights, HRW etc. The alternator was replaced but no change, using the 'paint stripe' method we found the outer and inner pulleys were rotating at different speeds but only when the belts were under load, interesting there was no squealing or noise from the HB, I think the compressor seizing strains the bond between the two pulleys and starts the eventual failure.
Sorry for the long winded post but it may help someone in the future?
regards
Dave