97 dodge neon running hot

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Jul 9, 2007
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#1
last week my dodge ran hot while driving slow... faster i went the temp gauge would go down.. turned on heater fan to keep some heat out and was able to get car home. no signs of overheating other than idiot gauge on dash.. removed thermostate and checked for problems, thermostate opened up in pot of water so was not defective... put back in and started engine again. thinking fan not working... nope that was running. was fine on coolant... took to mechanic, they checked it out. everything was fine.... replaced thermostate thinking it might be sticking.... now runs fine until you are about 85 on highway... and temp gauge will start to climb... any ideas? sending unit maybe? car has about 300,000 org. miles.. most org. parts... replaced water pump about 4 years ago..
 

Dave

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#2
wow thats a lot of miles to have on a car to have mostly original parts.
i would do a flow test on the system, you could have a partially clogged radiator or you pump might be going bad.
what color is the coolant?
does it look rusty in the radiator?
 
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#3
Have a block test done might have a bad head gasket. This is a chemical that reacts to hydrocarbon fuses that end up in th coolant and will change the color of the chemical from a blue to a yellow or green. If it changes color at all it means you have exhaust in your cooling system most likely a bad head gasket or could be a cracked head or block. These engine are prone to oil leaks from the rear drivers side corner of the head gasket area. A shop can also use a gas analyser to check for exhaust gases in the cooling system. But make sure you have no cold spots on the radiator as this would indicate a plugged core. Good luck!! Greasemonkey :)
 
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#4
the fluid is bright green... same as out of the jug...we had the oil leak and had that fixed several years ago.. running normal speeds, even city driving the car is running normal.. the gauge only goes up when we are pushing it on the highway.. mechanic told my son to bring it back and he will put it back on the diagnostic machine and see what he can find....