My '97 Neon has started to run hot when I sit still for more than minute or so. I have checked the water level and even if it is full, eventually I am having this issue. Once I start moving , th

start the car let it run 4-5 minutes. shut it off , let it set 5 minutes check level, sometimes it takes 10 -15 time to get it to cycle all the air. even a short trip around the block a few times and always making sure to fill the reservoir. the new closed systems are a pain to get all the air out. also remember to have the heater on in full heat position to allow the system to circulate through the whole cooling system.

Have you verified that system has been "burped" of air? That the fans kick on? Check radiator hoses for kinks. You can try running without the thermostat to see if that helps and can identify if the thermostat could be a problem. You may need to check your coolant mixture too.
Sounds like you have reduced flow or restriction in cooling (heat exchanger) as it runs fine at cooler temp but can't keep up when it gets warm.
New parts don't always equal working fine parts.

check the following items:

1. are you still running on carburetor? if yes, have your carb cleaned first
2. are your water/coolant levels in radiator and coolant reservoir full? if no, have your radiator overhauled.
3. is your water pump working? you can check it by doing the ff:. when your engine is cold, remove your radiator cap. start the engine and let it run for a few minutes until it gets hot. then check if water in radiator has a swirling effect.
4. check your oil level. you can check it by looking at your dip stick

Sounds like you could be low on coolant, even more so because the air starts to cool down, check coolant level with engine cold, never open a radiator when hot.

SOUND LIKE ENGINE RUNNING HOT.MAKE SURE COOLING FAN TURNING ON. WHILE ENGINE IDLING WATCH TEMP GAUGE AS THE TEMP CLIMB COOLING FAN SUPPOSE TO TURN ON IF NOT.CHECK FAN FUSE AND RELAY. IF BOTH GOOD HOT WIRE IT. NO RUN REPLACE FAN MOTOR IF FAN MOTOR DO RUN. YOU COULD HAVE A FAULTY COOLANT TEMPERATURE SENSOR OR SHORT IN FAN CONNECTOR OR WIRES. CHECK COOLANT LEVEL.MAKE SURE YOU HAVE 50/50 MIXTURE OF WATER AND ANTIFREEZE.TO BE ON SAFE SIDE REPLACE THERMOSTAT AND PRESSURE CAP.

You probably just need to "burp" your cooling system. Run the car (from cold) with the radiator cap open and the heater on full blast. As the engine heats up and the water level goes down, fill it up until it stays full and starts to overflow.

Regards,
matt

1997 Plymouth Neon, have replaced radiator, radiation cap, thermostate and hoses, still run hot. Fans do not seem to come on, where is the temperature sensor on this vehicle?

The engine is kept cool by a liquid circulating through the engine to a radiator. In the radiator, the liquid is cooled by air passing through the radiator tubes. The coolant is circulated by a rotating water pump driven by the engine crankshaft. The complete engine cooling system consists of a radiator, recovery system, cooling fan, thermostat, water pump and serpentine belt.

Check the coolant level in the recovery bottle or surge tank, usually mounted on the inner fender. With the engine cold, the coolant level should be at the FULL COLD or between the FULL HOT and ADD level. With the engine at normal operating temperature, the coolant level should be at the FULL HOT or HOT mark. Only add coolant to the recovery bottle or surge tank as necessary to bring the system up to a proper level. On any vehicle that is not equipped with a coolant recovery bottle or surge tank, the level must be checked by removing the radiator cap. This should only be done when the cooling system has had time to sufficiently cool after the engine has been run. The coolant level should be within 2 in. (51mm) of the base of the radiator filler neck. If necessary, coolant can then be added directly to the radiator.

While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat.

Worn caps should be replaced with a new one.

Periodically clean any debris; leaves, paper, insects, etc. from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.

Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful, the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not move them again. It is recommended that the radiator be cleaned and flushed of sludge and any rust build-up once a year. If this has not been administered within the stated time, this may be why your vehicle is overheating at this time. Have the Radiator flushed asap if this is the case.

Now, if the coolant level is proper and, the cap is in fair or good condition, i would advise to move in the direction of the cooling fans and sensors as well. These fans are vital to the cooling process as well. The cooling fans must cycle in intervals to keep the coolant cool during stop and gp driving or, long idle. They are also very important during the operational period of the AC during travel as well. i recommend inspecting the cooling fans while the engine is running. they should cycle during the running period. if thsi is not the case, you will need to test the operational value of these devices. The test procedure follows below


TESTING


1. If the fan doesn't operate, disconnect the fan and apply voltage across the fan terminals. If the fan still doesn't run, it needs a new motor.

2. If the fan runs, with the jumpers but not when connected, the fan relay is the most likely problem.

3. If fan operates but a high current draw is suspected continue with the following ammeter TESTING.

4. Disconnect the electrical connector from the cooling fan.

5. Using an ammeter and jumper wires, connect the fan motor in series with the battery and ammeter. With the fan running, check the ammeter reading, it should be 3.4-5.0 amps; if not, replace the motor.

6. Reconnect the fan's electrical connector. Start the engine, allow it to reach temperatures above 194°F and confirm that the fan runs. If the fan doesn't run, replace the temperature switch.



Ok, Now we will move on to the next possible issue. The water pump. ok, due to the fact that your pump is driven by the drive belt, you will need to start the engine and listen for bad bearing, using a mechanic's Stethoscope or rubber tubing.

* Place the stethoscope or hose on the bearing or pump shaft.
* If a louder than normal noise is heard, the bearing is defective.

Replace the pump in this case.

You will also notice leakage around the pump housing if the seal has failed as well. this will strain the impeller and, ruin the pump.

probrally the thermostat or water pump

Take rad cap off when cool & run it for a while with the heater on (not defrost) and top up coolant as needed in rad, about an inch or 2 from top of rad. Let it run until you see rad fan come on & off about 2 or 3 times at operating temperature. Then replace cap, top up return bottle to proper level, and try that. Probably still air in system. If that doesn't cure it, I'd look at faulty or incorrectly installed thermostat, which would be a trip to shop that installed it, if it were me.