2005 honda civic replaced entire cooling system still overheating

I have a 2005 honda civic. About a month ago it started overheating. Drives Ok on the highway but heats up to the H mark almost as soon as I get off the highway. Have replaced the water pump, thermostat, radiator, flushed the system, most hoses, fan, 2 sensors, timing belt, spark plugs and had the head gasket checked 3 times by 2 different shops. Both said it was fine. The mechanic that has done most of the work is baffled. Says he has never seen anything like this and is at a loss as to what to do next. I am supposed to drive this car halfway across the country in a week to meet my husband who is in the air force. Should I just sell this piece of junk!? Help!

When it gets hot check all the cooling fans are working.

Like Barky says, most likely a cooling fan is not turning on. Not sure but I think your car has two, right behind the radiator. With the car parked, start it up and let it idle 10-15 minutes. Both cooling fans should come on as the engine heats up. If they don’t, have your mechanic find out why.

Open the hood, start the engine and turn the AC on. Both radiator fans should start running. If not there’s a problem with the fan relay.


Because it’s not overheating on the hwy I would start with the fan. (The highway wind is blowing it cool, so the pump and thermostat are likely OK, as well as the radiator.) I agree with Tester – fan relay, since you’ve already changed the fan. It has two fans; did you change both? Replace both relays. Barkydog is right, you can check the fans when it gets hot. Relays.

Make mine another vote for the relays. But if that doesn’t work, I suggest renting a car and having the Civic shipped, then find a good shop when you get to your destination. This problem is readily diagnosible by a good mechanic, and that should have been done up front. Swapping parts out until the problem disappears is not diagnosis, and it sounds like that’s what your shop has been doing. Relays are easily tested, fans are easily tested, radiators can be tested for flow and “mapped” for internal blockages, T-stats can be tested (and when one is changed and the problem persists, I believe they should be). In short, I’m sorry to say that you’ve paid for a lot of unnecessary parts and labor.

I also want to offer a sincere thank you to your husband for serving and yourself for accepting “the life”. There’s an old saying, “they also serve who sit and wait”, and I believe the saying is far truer than nonmilitary people realize. God bless you and yours.

Here are the diagrams. Fuses and relays need to be checked if fans are not coming on when engine gets to temp and AC fan comes on when ac is on.

With all the parts I would have tried changing the temperature sensor too. I like changing things. I had a 79 truck which would turn on the engine light for no reason. I changed the sensor and had no more problems. It’s just one of the things that can go wrNog. I don’t want to talk about timing at all today.

Get a new mechanic. This guy is either trying to suck your wallet dry, or he is clueless.

hose off the condensor. My old 1999 Accord V6 with 253,000 miles was overheating (Gauge in the red). We hosed dirt and grime off the condensor (the part with fins in front of the radiator) and it stopped overheating.

Check for fan operation. It’s a (very) simple test that most anyone can do…just keep hair, lose clothing, etc away from moving parts.

To do the test: prop the hood open. Start the car. Wait around until it reaches normal operating temp (temp needle roughly in the center). Within a few minutes, the fan should start up. If it doesn’t, and the car starts to overheard, you’ve diagnosed WHAT is wrong…now just work on WHY.

I’d also ask if the temperature has been read off the OBDII port in real time. That will tell a mechanic if the coolant temp sensor (often a different one than the dash sensor) is providing useful data.

Heck, worst-case scenario, the fan can be wired to come on at any time the key is on (if nothing else works) so that you can make your trip safely.