Dear folks: I am working on a similar problem with 81 TD turbo...engine running at 100C around town and close to 120C when I went to Tahoe through the hot central valley a couple of weeks ago. Coming back I hit red on Donner Pass and pulled over. Did not lose much fluid and after 30 min wait made it up and over at about 115C. When home I ran all the tests that you can find on an older thread from last year (use the search function) and narrowed it to fan clutch and radiator. I replaced the fan clutch because it was not putting out and dropped normal op temp very slightly, then I pondered doing the citric acid flush described in the CD and have some on order before spending $317 for the new behr rad. I do have a hot top hose and a coolish lower hose so I was not certain about this. While I was pondering this I noticed that the oil cooler fins were clogged with the normal engine oil/dirt sludge that you find on the side of the engine (from blow by out of the oil filler cap area, etc). So I sprayed the oil cooler fins with Gunk engine degreaser and waited the 10 mins and blew out the fins from the back with a high pressure washer. This dropped my operating temp 15C ! Now I am running at 85C I am HOPING this will do it. I did a stress test on a steep hill yesterday and never went over 100C so it looks good. I guess the point is that problems with the oil cooler are separate from the radiator proper. Both get replaced with a new rad but how nice to save the $ if you can.