A bad fan clutch will usually cause low speed overheating and no problems at highway speed. I had a high speed overheating problem before and it turned out to be inadequate flow/heat transfer in the radiator, corrected by installing a new one. Maybe the recoring didn't go as well as it should have? The coolant mix is 50/50, right?

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.