04 Pathfinder running hot

[Ronjackson]

Hi I'm having trouble with my vehicle running hot. I was for sure it was a bad thermostat. I replaced the thermostat and now I have cold heat and its still running hot...

[Ronjackson]

Its a 2004 Nissan Pathfinder

[Bubba1]

Pathys have always had a good reliability reputation. But keep in mind it's a 16 yr old Pathy, so it's getting to the point where original, more expensive components are becoming possible issues. Checking the thermostat was a wise first try. You mentioned "cold heat" plus it running hot. To me, that sounds like a possible clogged/bad heater core, which can cause overheating as coolant circulation is reduced, plus no heat, of course. Hopefully it's something far less expensive than that, like low coolant, or an inoperative fan, or tired water pump, but the heater core would be my guess.



Good luck.

[AZhitman]

^ Agree with Bubba. I'd first bypass the heater core to see if that helps with the overheating. If so, the heater core is the problem.

If that doesn't solve the problem, my next steps would be: replace the radiator cap, run a pressure test, check to make sure the fan clutch is not spinning freely when cold, and THEN consider the water pump may be failing.

[Mike W.]

Seems like I've head about problems bleeding the cooling system, so that might be your problem. Also I believe there are two thermostats, one of which is difficult to get to. Did the lack of heat start just suddenly? If so it's probably not the heater core. Has it slowly started running hotter and hotter or all of the sudden? The radiator is on the suspect list too, it's 16 years old and may be plugged or restricted.