Why does my car run hot on longer journeys?

I have a 2001 Mercedes-Benz CLK convertible and it has started running warmer on longer journeys. The water and engine oil are topped up. It normally runs at above 85 degrees then shoots up to 100 degrees, though lowers if I drop to 60mph. Is this an issue and any ideas to fix it?

Asked on 9 October 2019 by Alexbath

Answered by Alan Ross
From what you are describing we would suspect that the water pump is the problem. It may need replacing.
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