Ran across this post on the 80's list from a guy in Australia-
"Gday,
I wrote a week or 2 ago about my 1hz overheating up hill. From ringing
around radiator specialists, the likely cause is probably a blocked
radiator and not the clutch fan. The cruiser has only done 150k.
One bloke told me they block up with Aluminium Oxide (or something like
that) from a reaction with the engine. This is in the form of a fine
powder. His advice was to flush the cooling system with straight Vinegar
(cleaning grade). This apparently replaces the protective coat. Then
drain it and run the engine briefly. The same active ingredient may be in
thoses radiator flush products. I will also replace the thermostat just
to be sure. I will also get the radiator flushed.
Linton"
"Gday,
I wrote a week or 2 ago about my 1hz overheating up hill. From ringing
around radiator specialists, the likely cause is probably a blocked
radiator and not the clutch fan. The cruiser has only done 150k.
One bloke told me they block up with Aluminium Oxide (or something like
that) from a reaction with the engine. This is in the form of a fine
powder. His advice was to flush the cooling system with straight Vinegar
(cleaning grade). This apparently replaces the protective coat. Then
drain it and run the engine briefly. The same active ingredient may be in
thoses radiator flush products. I will also replace the thermostat just
to be sure. I will also get the radiator flushed.
Linton"