Overheating Honda civic with full coolant?


2002 Honda civic has had overheating problems and had the radiator replaced. Water pump is fine as well but now the temperature keeps fluctuating . I drove for about 30 min in town and it’ll usually be a little below the middle but I saw the needle go slowly to the middle then 3/4 from the top and then it…

Check the following
1. low level of coolant
2. bad radiator cap
3. water pump malfunctioning
4. clog radiator
5. fan not working properly
6. loose belt
Hope this helps!

Always start by checking the fluid level, if it’s correct then there could be a problem with the fan not kicking on, wires not installed properly or it wasn’t connected at all. If it is kicking on, go in front of the car when the fans on and make sure it wasn’t installed backwards, it’ll be blowing air out the front of the car instead of sucking air in like it should be, yes some shops really do accidentally install the fan backwards. Reason I think it’s the fan is because, from what it sounds like, the car will overheat at idle but when moving the temperature will tend to drop back down or fluctuate because of stop & go traffic and city driving. At 30mph+ there is sufficient air being blown through the radiator without use of the fan to cool the coolant but at idle or speeds below 30mph there is not enough air flow to cool the fluid without a fan and if the fan is failing then the coolant will not be able to cool down thus overheating the engine.

Another possibility, thermostat failed or the wrong temperature rating thermostat was installed. Or the radiator cap is faulty or one with a different rating was installed than the recommended one which I think is around 16lbs. Radiator caps hold pressure in the system to keep the water from boiling and creating air pockets, if there’s no pressure the water will boil at at high operating temperatures and create air pockets that will overheat the engine.

I don’t normally deal with Hondas, but this is an all-too-common issue with any car. Overheating + no heat from heater= Air in coolant. It’s caused by adding coolant incorrectly. To bleed the air out, do the following:

1. Remove radiator cap (not the overflow bottle cap). It is found by following the top radiator hose back to the engine.
2. Start engine and turn heater on all the way hot with fan speed maxed out.
3. Watch as bubbles come out. Now add coolant to proper level, wait for it to stop bubbling and replace the cap.

This is the correct procedure for topping off coolant as well. You need to run the heater to make it pump coolant through the heater core and force air out of those lines as well. On my Mazda RX-7, there is a coolant level sensor in the top of the radiator and air bubbles get trapped there WAY too often. You probably don’t have a coolant level sensor, but the procedure is the same. My mom’s 2000 Neon had the same issue from, you guessed it, her adding coolant into the overflow bottle.

Make sure you don’t have an air pocket in the system by opening up the radiator cap, turning your heat on high, and letting the car run for awhile. If that doesn’t solve it, check to make sure your cooling fan(s) are working, and also test your coolant temperature sensor. Like the previous poster said, though, halfway isn’t out of specs. Chances are, if your thermostat was bad before, it failed in the open position, and your coolant was constantly cycling through the radiator, instead of the thermostat opening and closing. Now that the thermostat is fixed, it is probably operating at normal temperature.

Have you stood there and made sure the fan kicks on? there are usually two, one for the AC and one to cool the motor when running. These kick on via a switch. If the fans dont run, you will overheat. Try turning on the AC and driving. In the winter that may be enough for now.

either the thermostat or the radiator cap is bad

my friend had a similar problem but at idle the resevoir tank boils and the thermostat goes to H
he replaced the cap and problem went away

maybe the thermostat went out. its a cheap part to buy at a auto parts store. it shouldn’t be an expensive repair, if it is in fact the thermostat. the thermostat tells your car how hot or cold it is. it kicks in the fans when it needs to. have you checked to see if the radiator and ac fan turn on? turn the car on and let it run for 10 minutes. if only one fan comes on or if they don’t come on, then you need the fans replaced. i had this problem this past summer in my accord. i got the fan for 30 bucks at a salvage yard. also when i went to replace my thermostat, it didnt have one. i hope this helps out. good luck

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