Hello everyone! Trying to diagnose an overheating 2004 Neon SXT. Purchased a few months ago. Previous owner recently had the cylinder head machined, new head gasket, water pump & timing belt. So far I have only changed the inexpensive parts, radiator cap, thermostat and temp sending unit/sensor. Also have flushed the cooling system, poured in new 50/50 coolant and have burped the crap out of the system. I gently separated the radiator from the AC condenser and the radiator fins are clean, not bent with no debris blocking airflow. Fans come on as they should and are running full blast when the gage creeps up. Overheating is intermittent it seams. Most of the time temp stays at 2nd mark from cold (6 total marks on temp gage C=0, H=5), but then for no apparent reason the gage will creep up to the 3rd mark and sometimes a little past it. Usually, we can turn off the AC (open the windows) and the temp will return to the 2nd mark.

Summer time here in Indy, so in the 80's. I hate to keep throwing money into parts, next might be a water pump or a radiator, but I'm not convinced that is the problem. Nor do I think yet it is a head gasket, because I would think the engine would overheat all of the time.

Car has about 170K on it. Could the radiator be breaking down inside? Could the "new" water pump be weak? Or is this a head gasket. Looking for your recommendations, where to go next. All replies are greatly appreciated!!

 

Is the thermostat working properly? Spring side toward block? All the air birped from cooling system that you can get out? I once had a bad heater core leaking that would allow air to suck back in the system over night which caused my temp to get higher then normal so I pulled the heather core hoses & connected them together with a piece of pipe during the summer. When the water pump goes bad thats its usually will drip from timing belt cover, when you flushed it was there an shiny or chunks in the fluid? Sometimes they use radiator sealer which will eat a water pump seal over time. Just my experiences

 

Are you saying it's overheating because it goes to the third mark? If so, the car is fine. Overheating is the needle pegging at the top of the gauge.