Q: 2006 Xterra 4x4, 4.0L V6. Engine is overheating. No coolant leaks. Replaced thermostat. Flushed radiator. Fans work. What to do?

asked by on March 20, 2017

06 Xterra with 97K miles. Just had tranny rebuilt. Within 10 miles of tranny shop it overheated. Never had heat issues before. I replaced the thermostat and flushed the radiator. Filled with fresh coolant. Next day engine ran at normal temp for 40 minutes of driving to and from work. Overheated in the driveway when I got home. There are no leaks of any kind. The tranny shop said they found no signs of water or coolant in the tranny. The serp belt has proper tension. Water pump shows no signs of failure. Pump/fan shaft is tight and spins freely with little pressure. When it gets hot the coolant in the reservoir looks/sounds like it's boiling. Rad and reservoir cap fit tight. The main fan appears to be working but at what % i dont know. Elec fan comes on when heat rises. So frustrated! I'm not sure what to do next. I am considering the fan clutch but not sure how to troubleshoot that. What could be causing the overheating? I'm mechanically savvy but never messed with the coolant system.

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

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Hello, thank you for writing in. Overheating issues are very frustrating. When in this situation, you will want to go ahead and test the radiator cap and make sure it is regulating pressure correctly. Secondly, the water pump needs to be tested or replaced. Although it may seem like it is working, it may not be pumping enough coolant through the system to keep up with heat transfer needed. You may also want to check the oil and make sure it is in good condition, as the oil plays a large role in regulating engine temperature as well. For more help with diagnostics, contact our service department to schedule an appointment.

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