It depends how hot it is where he lives. I have run my SDL without the fan clutch and it hasn't really affected anything, idle temp's were up slightly. But it was 50 degrees out as well. I don't think the radiator is working as well as it could.

If it was sudden it's not the water pump, but I have seen them with the vanes worn down to almost nothing.

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2006 CL500
2009 C300 4matic
1969 280SE
2023 Ram 1500
2007 Tiara 3200