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2004 honda civic overheating, any advice?

I have a 2004 honda civic ex that is overhearing while in traffic or long red light. I have replaced the radiator, thermostat, and replaced one of the cooling fans by my mechanic about 3 months ago. The mecanic pressure tested the system and said the head gasket was good. The car has been running fine until a few weeks ago when i was stuck in traffic and the car starter overheating again. I’ve noticed that the coolant stays in the overflow tank and does not go back into the radiator. I am not a mechanic and the extent of my knowledge about cars in basic. If anyone could help me out with a possible issue before i take it back to the mechanic to see if its something I would be an easy fix for me to do. Thanks for any help its very much appreciated.

If the car has AC, has anyone checked to see if the condenser in front of the radiator is packed with bugs/debris?


The coolant not going back into the radiator is an important clue. The hose between the radiator and the overflow tank may have a hole. Or the rad cap may be bad. Or the head gasket may be bad and combustion pressure in the cooling system is keeping the valve in the rad cap from opening and letting the coolant back into the radiator.

Are you ever losing coolant? Has the running engine, with the rad cap off, been observed for bubbles at the open rad? Has a hydrocarbon sniffer been held over the open rad with the engine running? A chemical test been applied to the coolant?

That’s not how you test a head gasket

You test for combustion gases in the cooling system

The mechanic should already have that tool

He can carefully also use the 5-gas analyzer to test for those combustion gases

You can use the block tester to check for a blown head gasket.

You can pressurize the cooling system to check for a blown head gasket.

You can do a cylinder leak-down test to check for a blown head gasket.

Or, you can remove the radiator cap when the engine is cold, start the engine and watch the coolant to see if bubbles form as the engine idles to check for a blown head gasket.

All these methods work.


I do not seem to be loosing any coolant, and i have had the cap off with it running and have not seen any bubbles. Ill see if i can get the test the others have suggested.

I had a 1993 Oldsmobile 88 where the coolant was not being drawn from the overflow tank back into the radiator. I found that them hose between the overflow tank and the radiator was collapsing when the engine was turned off and cooling. The partial vacuum created was enough to collapse the hose so it acted as a check valve. I spent about a $1.50 for length of hose and put in 10 minutes of labor and the problem was solved.

Ok thanks for the idea, ill give that a shot as well!

How many miles?

Got 180k, its my work car gets good gas mileage and its cheap

It’s at the mileage where a bad head gasket would be high on my list of suspects

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Does the car have an automatic transmission?


Yes automatic

Check the color and odor of the transmission fluid.

If the fluid is black and has a burnt smell, it means the transmission is running hot, which can cause the engine to overheat.


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Ok thank you for the advice! Say that was the issue, would the transmission need some work then?


The transmission would require replacement.

How often has transmission fluid been serviced?


I checked the fluid was dark and dod have a burnt spell. I havent had that serviced in a while. I also havent had any issues shifting gears or anything