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So recently my car throws white smoke through the exhaust but its not constant. Happens if i come to a complete stop for like a couple minutes. Coolant is good and oil change is done. Car starts to overheat little by little after 15-20 minutes of running. Anyone have any suggestions?

 
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UPDATE: Changed all the ignition coils and spark plugs and smoking stopped but it keeps overheating after 15 minutes. Someone suggested it being the radiator.

 
Rep Power: 518

What car do you have? Year, engine size, mileage?


Is the radiator full?
Do the radiator fans operate correctly?

 
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2007 Honda Civic EX
170k miles
Yes its full and yes the fans work.
Just went to autozone to get my codes checked and got a P0400 code

 
Rep Power: 518

Is the smoke white or is it pale blue?
Does it smell like antifreeze or does it smell like oil?
Does it hang in the air a long time or does it dissipate quickly (steam from plain water will dissipate quickly)

Has it had a thermostat replaced?
Any liquid leaks on or around the thermostat or its housing on the head?

Block cracked leaking coolant out?

The code P0400 is related to EGR (system leak detected) and that valve sits atop the thermostat housing. Any leakage in the pipe between cat and housing could set the code, so could clogs and the like. (I don't remember having to chase that particular code myself)




When it's showing hot on the gauge, are the radiator fans running at that time?
If the fans are running, feel the temperature of the air being blown. Is the air screaming hot or is it lukewarm?

 
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UPDATE:Smoked stopped once we changed the Ignition Coils. Just replaced the EGR, Coolant Temp sensor, Has brand new coolant, fans work, and the thermostat. No leaks. but still overheats after 10-15 minutes. Last choice i have is changing the radiator and if that doesn't work then its the head gasket. My dad had the same issue on his f150 where it was overheating so he changed the water pump because it broke and it was still overheating so he then changed the radiator and its been good ever since. Oh forgot to mention it has a brand new water pump as well.

 
Rep Power: 518

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The air is lukewarm

 
Rep Power: 518

Sounds like a radiator issue.
Fan's can't pull the heat out, or the heat isn't getting into it (flow restriction)

Is the plugging on the inside or the outside? Ever since Honda went to the blue type-2 coolant it's been pretty rare to see lime/calcium/scale clogging inside IMO, but if someone didn't stick to that coolant, well, anything is possible there.

Does it have 170k worth of bugs/dirt/sand stuck in the thin little fins of the radiator and/or AC condensor? That could restrict air flow and cause overheating too. Garden hose and sprayer, wash it out while the radiator is out.....Spray from the engine compartment out toward the front, you might be amazed at how much garbage can be trapped in there.

 
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UPDATE: Car is finally back to normal. Changed the radiator and it didn't overheat like it used to. After putting in coolant i idled it for 15 minutes, took it for 10 minute drive, then idled it for 10 more minutes and finally took it to the highway to test to see if it wouldn't overheat on there and it was good, drove it for 15 more minutes and it did not overheat. So the cause of it was the radiator, fixed it by changing it. Hopefully this helps for anyone that is having the same issue.