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Q: 1999 Jeep Wrangler overheating at highway speeds

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What could cause Overheating at highway speeds. Already replaced radiator, thermostat, water pump and hoses

My car has 97000 miles.
My car has an automatic transmission.

Hello. If this only occurs at highway speeds, then you may have pressure build up in the cooling system. This is typically caused by a leaking head gasket. If there is a slight leak, then combustion pressure will build up in the cooling system and cause this to occur. A block test would need to be done to verify this. If you want to have this looked at before throwing on any more parts, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose the overheating issue and verify what needs repair.

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