We have a 1999 Neon that we purchased 2mos ago and since then we have had the Head gasket check and it is great, nothing wrong with it. We replaced the thermostat and the temperature gauge, replaced the radiator cap as well. We have had it flushed twice and all the hoses checked. It overheats mainly if we drive over 60, which makes highway driving pretty hard. It also overheats if we drive long distance (on or off highway). Also when ever you turn the car off it bubbles. And if you check the radiator it will be low to extremely low on fluid but the reserve tank will be full. So it seems like when it starts to get hot the radiator will overflow into reserve tank but it never pulls the fluid back into the radiator. Any ideas anyone what could be going on? Is the radiator bad or the heater core?? Help please we live in mo humidity is bla here, so over heating car is not good.

 

Could be a bad hose or a clog, gently squeeze the hoses and see the strength and check all fuses and such. Make Sure there are No leaks in the radiator itself. It's probably something really small and dumb, did you use an aftermarket cap? Could be applying to much pressure and not in enough clearance or vise versa. Check the fluid and see if there's an excess of metal or dirt. Andget back to me

 

Have you checked to see if your cooling fans are working? Could be a relay problem. One is for 1 fan and the other comes on when using the A/C.

 

Could also be a fuse and or the coolant temp sensor.

 

Hoses are perfect, water pump perfect, no leaks in the radiator or head. Had a pressure test done, its fine. The cap is not a after market, The problem is, is that we start out with our radiator full and when the car starts to get hot the coolant is flowing into the reserve tank but not going back into the radiator. Instead the radiator just keeps sucking in air and then over heats. We have no clue what to check or look for to see why its not pulling back the fluid, only air.

 

Coolant temp sensor was replaced and checked every fuse in the car 2 to make sure they are all good.

 

Sorry forgot to add also fans are working good and blowing the correct way, Ive had 5 different mechanics looking at this car and they think they got it and 20 mins later on the way home or what not, it over heats or starts to over heat and theres air in the radiator again.

 

Check the overfill bottle lines for crakes or a brake in it. You may want to remove the overfill bottle and inspect for cracks also

 

Take the thermostat out and fill the block with coolant threw the hole. Then reassemble . Try that