CLK320 help

[DP400]

Evening all

Im going to look at a year 2000 clk320 aventgarge tomorrow. Not being particularly knowledge about Merc's can any of you guys give me any pointers for things to look out for. The seller tells me the temperature gauge doesnt work and that this is a faily common failing on these cars. Any help you guys can give me will be much appreciated. Hopefully a silly question but can anyone confirm that the engine is chain driven rather than belt driven?

Thanks in advance