Well, you needn't go to the Sahara, or tow an elephant. Just add 6 adults, hook a 4x4 trailer, and go to Namibia in winter. That gauge (VDO) hardly ever gets below 100 C. Jim is right. In Africa a TDi is undercooled
My son called me today whilst on his way back from holliday. After a long climb up a mountain pass, (in the Karoo; a dry, hot area) the high temp alarm in his Disco TDi started screaming. He stopped, and waited for the engine to cool down. Phoned me later to give me an update on the amount of cars standing by the roadside with engine hoods lifted. Various makes
In Africa, a TDi's cooling capabilities get well tested !