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Q: 2008 Hyundai Sonata running hot. Fan comes on and the fluids back up in reservoir tank. I also changed the thermostat.

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It is running hot fluids is backing up into the reservoir tank, the fan does come on, so I changed the thermostat, still ran hot, so I changed the radiator cap, still ran hot, I have No leaks either, what could be my problem? Also let me add No service lights on in dash either.

My car has 132346 miles.
My car has an automatic transmission.

Hi there. Check the coolant and see if its flowing. If the coolant is not flowing, then the water pump may have stopped working. If the water pump is working, then the engine may have a blown head gasket making the exhaust gases enter the cooling system and causing it to boil. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your engine that is overheating.

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